Perverted Moth Build

Nationals QOTD

2012-01-11T08:35:00.000+10:00

Nationals Quote of the Day Round Up:

All of the people quoted below were heard second or third hand and are probably taken out of context if not all together wrong.

Day 1: "If another local says 'it's not normally like this' i am going to throttle them cause I have sailed here seven times and it has always been like this" (les, standing in teh rain)

Day 2: "Every wave is laughing at me" (scott's report after being sent out to check the course)

Day 3: "Is there sailing school on today? All of the boats are capsized." (random old guy on the beach)

Layday Eve Dinner: "While I was in the change rooms this afternoon I saw something very impressive" (leigh on budgie, later budgie dropped his pants to show it off)

Rough as Guts

2012-01-09T08:14:00.000+10:00

Rough conditions yesterday, perfect for rum drinking.

Invitation Race

Jack Sherring (QLD) won in a lumpy drift-a-thon (with some marginal foiling) while the rest of us got seasick and heat stroke. Well done Jack.

Race 1
Rumour mill was rife with 20 knots predicted to come soon. After a long wait for the wind to fill in (from nothing) the starter was keen to get some racing in before a front arrived. With some boats still trying to get to the line the race got underway in sub-foiling conditions. This wasn't to last long and within a minute it was all systems go, ~15knots. Upwind was fine in the lumpy stuff but downwind was another story. Plenty of cartwheels ensued as ppl tried to sort setups.

Race 2
I don't know what happened because I pussied out of the first race but the procession of borken or flooded boats was enough to validate my decision to retire for the day and drink rum.

Today is shaping up to be a bit windier from the West. Don't know what that means for the waves, we'll soon find out. End of the week is looking good.

Oddball results to follow but we think Markla is winning, which is very odd.

Rum Squad

2012-01-07T08:13:00.000+10:00

One from our part time contributer, Alanla?... Alanarkla?... Alla?

Rum Squad has not had a tunning seesion together in quite some time, individuals have been training hard during the year. With an appropriate warm up even this weekend I'm sure the performances of the squad members in apperance at the Nationals will do us all proud.

Rum Squad shall be on the attack at this year's Australian Moth Nationals

Wivenhoe

2012-01-01T15:04:00.004+10:00

Spent the last two days blasting around Wivenhoe dam in 10-20 knots with Mark, Rob and Tom. Hit new record peak and 10 second average speeds without feeling out of control. After some time off the water due to unfortunate breakages and control system modifications it was good fun and will try to do it some more after the nationals.

Chicken Rigs

2011-11-07T10:46:00.003+10:00

So I had my ass handed to me yesterday in 17-20 knots (recorded, not guessed).

The wind wasn't the only contributing factor, I was being a scaredy cat with a lot of traffic around, but it made handling tricky, particularly at any hotted up angles and while trying to go slow (pre-start etc).

What are ppls opinions on chicken rigs? Usefulness, size, shape...

I've seen two recently, a purpose built full height one (higher aspect ratio) and an old KA with the bottom chopped off.

Good weekend

2011-11-03T17:54:00.002+10:00

Just a quick on water update.

Had a good three races on the weekend. Jack, Markla and I were competing against a 16 foot skiff, a 29er and contender.

Markla and I are improving, Markla with his boatspeed and pointing (after some spreader changes) and my gybes are coming along nicely, about 50/50 foiling and half the rest with light touch-down before powering off again.

a special hello

2011-11-01T11:20:00.000+10:00

a special hello to the two people this month who found the bloog (somehow?) by searching for Fonzie!

and before any of you eagle eyed people see me searching for it in the above image, it was just me seeing how far off the front page the bloog is. for those wondering i gave up at page 20.

resistance prediction, table of hydrostatics

2011-11-01T10:47:00.000+10:00

resistance numbers and table of hydrostatics now available as part of the design package.

i don't really have much to say about them except they may be useful for anyone doing a VPP where the lowriding, or partially supported case is of interest.

SLINO Weight Estimate (with pie!)

2011-10-28T20:31:00.000+10:00

here i am, friday night watching 7:30 queensland on ABC doing a weight estimate for a boat i have already built and weighed.

well, its one of the remaining files i promised with the design package. and maybe i am feeling a bit compulsive.

but it does show some interesting things. the centre of gravity is futher aft and lower than i would have expected as shown in the graphic below (note it excludes skipper weight)

the weight calcs result in the following numbers:
hull, paint, gantry = 11.87 kg
wings (alloy), tramps = 9.89 kg
foils, tiller = 8.50 kg
rigging, standing, running, control, mast, sail = 13.06kg

Total = 43.33 kg

This distribution is illustrated below.

this is clearly 6 or so kg overweight. as I have noted previously, changing the wings to carbon would save around 3 kg. changing to dacron tramps (rather than trampoline material) would save some too. and I need to change to carbon spreaders.

the remainder i think would need to come out of the hull. my construction method of laminating the seams of prefab panels results in a lot more bonding than a moulded boat (2kg i would estimate).

how else to save weight? maybe less hull, particulary in the foredeck. or if you were confident in your boat handling maybe a lighter panel laminate, like nomex and prepreg.

that rigging component is still a large piece of the pie. easy to see how a wing is viable from a weight point of view.

updated design files

2011-10-25T18:28:00.003+10:00

Some recent interest in the design has inspired me to complete the design package for the boat.

Lots of detail info here:

http://perverted-moth.blogspot.com/2010/11/slino-design-files.html

New drawings are:

SL2-E1-02__04A - Hull Construction Details
SL2-E2-01__02A - Centreboard Construction Drawing
SL2-E3-01 Stem and Transom Lug Construction Details
SL2-E4-01 Wing Mounts Construction Details

SL2-F4-01A - Running Rigging Arrangement

SL2-G1-01A - Control System Arrangement
SL2-G1-02A - Control System Parts

I am hosting them on google docs. if anyone has trouble downloading them could you let me know and i will investigate different hosting arrangements.

The Truth is Not-there

2011-10-07T22:03:00.000+10:00

Tonight's bloog is one from the vaults - my rather unpleasant, work necessitated Toastmasters experience. It is fair to say this speech went down better with the over 60s than the one on voluntary human extinction movement...

The Truth is Not-there

If the computer game THE SIMS 2 is anything to go by, getting abducted by aliens and bearing their children is as simple as buying the most expensive telescope and looking skyward.

While this isn’t going to harm your chances of getting abducted, there are a number of measures you can take to put your self in a more feasible position.

Today I will outline reliable means of being abducted by aliens.

Alien abductions are much more common than we think. Do you find yourself loosing time? Do you have missing memories. Do you find yourself in new locations with no memory of how you got there. Are you unexpectedly pregnant? If all of this sounds like last weekend. Then there is a strong possibility you were abducted by extra terrestrials. Does this happen every weekend? Multiple abductions are also common.

I understand those of you who want to have an alien experience face an uphill battle. The field appears rife with kooks and pseudoscientists desperate to discredit your chances. The prospect of medical testing or possibly becoming surrogate parents for alien-human hybrid super soldiers does not appeal to all. Most abductees describe the experience as terrifying or humiliating, but others describe them as transformative or even pleasant

Herein I shall outline reliable ways to get abducted. Then, how to determine the alien’s intentions and finally how to survive your encounter.

The methods to encourage abduction are simple, so lets start there

Be mentally prepared for alien abductions. If you come to terms with the possibility of abduction and prepare yourself physically and mentally, the aliens will look upon you more favorably. Find an inner mantra and mutter it constantly throughout the day. It is especially effective during the daytime in crowded public places where the aliens can sense the thoughts of those around you highlighting you as a perfect abduction candidate.

You can also hang around fellow abductees. Share their habits and interests. For some reason aliens like to take friends, family and associates of abductees. Then drive in your car along deserted roads in rural middle America during the early hours of the morning. When you see lights up ahead and your car radio goes crazy, then the car stops you know you’re getting close.

Make yourself an easy target for the aliens thru self medication of mind altering substances and alcohol. Intoxication will make you more likely to trip and fall and land in a UFO, amphetamines will sharpen your reactions and allow you to see or even catch a fast moving UFOs, and acid will elevate your awareness to tune your mind into the alien nexus and assist with tele-pathetic communication.

Of course your odds of abduction skyrocket, to excuse the pun, when you combine these chemicals in unfamiliar souroundings.

Once successfully abducted you should determine whether your alien means you harm

Can you establish the alien’s mood? If it is attempting to be friendly, chances are that the alien means no harm, but will probably probe you.

Notice how the alien is treating you. Trying to comfort is a much better sign than coming after you with a weapon, or the probe.

Look around you and see how the alien is treating the other abducted persons and animals. Are they harming them? Yeah, that also means your gonna get the probe

So How to survive your alien abduction?

I would suggest thinking pleasant thoughts about staying on planet earth. Aliens can read your thoughts and you don’t want him to misinterpret scenes of leaving earth or probes

If the aforementioned mind control fails, shout that you want to stay, in basic language repeated over and over. Even if their english is rusty the message should get thru eventually.

Reassure the alien that you mean no harm to him, remember that it has come from millions of miles away and is likely not to know what to make of you and your behavior either. Don’t brandish weapons at your first meeting if you can avoid it. It is hard to convince other humans that you mean no harm when you are brandishing your glock 9mm so it could be difficult to convince a completely different species that you come in peace and wish them to live long and prosper if you are armed.

Trust your instincts. If for some reason you feel uncomfortable around the alien see if you can gracefully get away from it. Try to convince it you need to check something out with your leader before attempting to represent the whole human race.

Should you failed non violent measures try fighting back. Even if the alien is stronger than you, as most of them are, putting yourself in their position who would take? Someone who just sits there and accepts they will get the probe, or someone who throws shoes and books at them.

Finally you can let them know that no-one has ever bothered to abduct you before, probably because you are too boring, or too normal. Most abductees are either an easy target, or crave repeated exposure to this marginalized lime light. So you can always try to convince the alien to seek out a more suitable candidate.

That brings me to the end of today’s discourse. You have heard how mental conditioning, chemistry and the right positioning can enhance your chances of abduction. Next ways to tell if you will be probed, and finally, ways to ensure you get back home safely.

I would recommend that you don’t talk about your experiences. At best other people will think your crazy – at worst you will find yourself followed by black helicopters and men in black. Many people want to be abducted so you can see why the government is so keen to cover this up.

When I look around the audience I see some skeptics amongst you, but to you I ask this: can you give but a single piece of evidence to discredit the facts I have outlined today.

Look to the skys people because they are acoming.

UFO? / Virtual Punter

2011-09-30T23:39:00.001+10:00

n4rks sent this to try to prove to me he has a boat. and it flys.

i think it is a rather sketchy photo, like those ones of nessie (teh monster, not teh wife), and ufos and stuff. therefore should be subject to doubt. i am even facing the otherway. and winning for that matter. well jack and steve are sort of in front but that's not the point.

while not sailing nor working and bored i decided to try maknig a version of virtual spectator in rhino script to prove i can do anything in that program. i think it is the best and at 1k worth every penny. i am rather pleased with the results. rendering of the video needs some improvement but it has a lot of potential, and once i have 2D nailed 3D rendered graphics should be simple. background images were systematically raped from google maps at 5 different zoom levels to make up a matrix of around 20,000 tiles. but that is a different story.

now i just need some decent GPS tracks.

Hobart

2011-09-26T15:50:00.004+10:00

I was in Hobart for a conference a few weeks ago and while sitting down for breakfast at 8am, noticed a lone rider carving up and down the Derwent.

Upon checking the BOM website the following was revealed...

17-31 knots in the hour or so on the water
11.3 deg lowest real temp
3.1 deg lowest apparent temp

Very keen...

housekeeping

2011-09-09T21:57:00.002+10:00

a couple of pictures i have been sitting on from the worlds, first courtesy of Thierry and the second from Ben Rankine.

UPDATE:

Karl,

I purchased a 2 piece mail foil off a friend at the worlds and spent most evenings adapting it to suit the boat. Only got it ready for the final day of racing. On the way to the start line, after 20 seconds of foiling it failed thru the socket, pushrod tearing open the TE of the vertical.

Once the lifter had departed, the rapid descent must have overloaded the bottom leg of the gantry, it bucking under compression. I have a Dave Lister style articulating gantry which saved the rest of the gantry, but it rotated up and snapped the tiller off on the hull.

I was able to recover the lifter vertical, gantry and rudder were still attached, but the tiller/worm drive/extension goned.

Windward Heel

2011-08-17T13:49:00.005+10:00

Could've sworn I posted this ages ago.

I was wondering why 15 degrees seemed to be about the right windward heel for best performance upwind. Also wondered how much lift was actually required by the foil at such a heel angle and the transverse force balance of a moth at such a heel angle. Was fairly convinced this was all related so I developed a spreadsheet to find the heel angle that balances the vertical and transverse forces determined from the righting moments.

If anyone wants a copy to play with, let me know and I'll email it to you.

China and New Boat

2011-08-17T13:15:00.003+10:00

Quick update, Markla is in China and I've finally bought a boat. All going to plan will pick it up Friday morning.

Clarke and Dawe

2011-08-01T14:18:00.001+10:00

something to correct for narkla's recent left leaning posts...

[Scene: A car yard. BRYAN is perusing the stock. He is approached by JOHN]

John: Morning! Looking for a new car?

Bryan: Nope. New Prime Minister, actually.

John: You’re the third one this morning. Anything in mind?

Bryan: You know....... nothing fancy, reliable, economical family model. Something to get the country from A to B.

John: You mean like a Howard?

Bryan: Yeah....a little Johnny. Nothing flash, does the job. Low maintenance, economical, sensible. Runs for years, no troubles.

John: So.... you used to have one?

Bryan: Yeah. About 10 years. Great little model – don’t know why I got rid of him -- biggest mistake I’ve ever made…

John: What happened?

Bryan: Traded him in for a Kevin 07.

John: Big mistake…

Bryan: Lot of people bought it. Good political mileage.

John: How was the Kevin 07?

Bryan: Came with a $900 factory rebate – that was good.

John: Anything else?

Bryan: Not much. Sounded nice but nothing under the bonnet. It was a lemon.

John: Didn’t stick around for long did it?

Bryan: Nah – had a factory recall. Shipped overseas and was never seen again.

John: What was the problem?

Bryan: Lots. But the final straw was the navigation system. Plug it in and it automatically loses its own way.

John: Whatcha got now?

Bryan: It’s a Gillard-Brown.

John: The hybrid?

Bryan: Yeah. The Eco-drive system – not a good idea. An engine that can’t deliver hooked up to a transmission stuck in permanent reverse…

John: Green paintwork with a red interior. And steering that always lurches to the left for no apparent reason – that’s the one?

Bryan: The Fustercluck model.

John: The only one they made, Bryan. Not the vehicle of choice for the road to recovery – but did they finish up fixing the navigation system?

Bryan: Made it worse. Turn it on and it does a press release, heads off in all directions and goes nowhere.

John: So that’s why you’re here?

Bryan: That’s right. I’m stuck with a government that's wasteful, expensive, ineffective and past its use by date. I don’t suppose you’ve heard of the “Cash for Clunkers” scheme?

John: Join the queue brother.

will get back into moths soon, just waiting for it to warm up.

and finish getting married.

and finish cresta #1.

Good photo of Mark from Worlds

2011-07-28T11:54:00.004+10:00

W00t cadel

2011-07-24T09:19:00.002+10:00

I'm off on a ride to celebrate

Course and Wind Plots

2011-07-14T22:27:00.003+10:00

A couple of plots showing the Speed, Apparent and True Wind Vectors from the ride around the park. Unfortunately the Kestrel turned off after 15 mins, which was only about 5 mins after the GPS started tracking. But the concept looks to work. Now to fine tune the weather vane for the Kestrel, it had a tendency to go berserk in the higher winds, but otherwise working alright.

Speed (no colour gradient)

Apparent Wind

True Wind

All Vectors (culled the data for clarity)

All Vectors (a lot of data to sift through)

Foredeck

2011-07-12T16:23:00.004+10:00

Just mucking around with some concept designs...

More of the hull, deck and wings to come. Not happy with them as a whole yet.

New Toy

2011-07-10T23:14:00.003+10:00

So I've been thinking for awhile that GPS data on its own isn't enough really. How do you know what the wind is doing? Sure you might be going faster, but there may be a few more knots of breeze, you may be cracked off a bit...sooo many variables exist. Putting a big boat data system on a dinghy is not feasible.

On the drawing board has been an affordable wind guage/anemometer that can be mounted on a dinghy. There's been many sketches, but most have a fatal flaw. Electronics are getting more accessible and feature rich, just look at the smartphones, why not implement something for dinghy sailing. Then this came along...

http://www.nkhome.com/kestrel/kestrel-4500/

This piece of kit is allowing me to test some ideas to see if some sort of wind recording device is feasible/affordable for dinghy sailors. It might be that just a windvane mount for it is necessary as opposed to a dedicated electronic device. There are a lot of options from a fully featured miniature computer system to a bare bones data logger. I see no reason a small smartphone can't be setup in a waterproof box to record and possibly output to a display the real-time performance data of a sailing dinghy.

I mounted it on a weather vane on the bike and rode around the local criterium circuit on a windy day to get some data. Playing with it now and will post on the results once I have them sorted.

Excuse the short, rambling post, I'm sick.

New New Thing

2011-06-09T10:40:00.003+10:00

My new new thing has arrived. It is sailing related, it is not a boat (although I'm looking at a few of those too). Once I've played with it a bit I will show you...

Second hand market

2011-03-23T20:13:00.003+10:00

So I've been putting this off for awhile because I'm not really sure what to say. So what better way to say nothing than write a rambling blog post on a dull Wednesday night.

Having been in the market for a second hand boat for over a year now, the current market frustrates me. There seem to be plenty of boats on the worldwide market, but I can't justify paying anywhere near the asking prices. A number of boats have come round and round with very slight price drops every couple of months. One of my friends boats included, a good quality prowler zero. (Sorry Al, any publicity is good publicity right? :)

It is an interesting marketplace. Secondhand boats don't seem to be selling as fast as would be expected for such a "popular"/"high profile" class. Owners also seem to be willing to hold onto boats for as long as required to get a good price.

Clearly some secondhand boats are selling, we met some at the worlds, but it doesn't appear to be many compared with how many are still for sale doing the round'n'round.

Price doesn't seem to be a contributing factor with plenty of new mach2's selling.

Maybe I'm ranting a bit here because of my desire to be on the water instead of blogging. Sure I can afford these boats, hell even a mach2 if i want to demolish my savings, but there would be little point spending twice as much to have the same amount of fun.

For now I guess I'll keep stealing Markla's boat (once it is back in working order). It was behaving quite well during the short session I had with it at the worlds. It probably won't get as much attention two weeks from now anyway.

In other news, Markla has plenty of video from a session at Southport a few weeks ago (Post it Markla!). Markla also has to fit a near new ONE PIECE fastacraft foil to his boat. Long story short, he bought a near new two piece fastacraft at the worlds, we fitted it in one day, moments into its first airborne run it disintegrated at the joint ripping the pushrod out the back of the strut, plus plenty of other damage to the main foil, subsequent crash destroyed the gantry and broke the tiller, tiller (and the raking mechanism) were lost overboard, Mark was very upset. Word is that John Ilett was very good about it later and swapped broken main foil for near new one piece of his own after the regatta.

Twatter - marklamarkla

2011-01-05T12:23:00.006+10:00

marklamarkla for twitter updates

who wants some?

2010-12-01T16:30:00.000+10:00

There is a factory outlet shop nearby selling these bad boys for $8.25.

You read right - 2.3kg of lasagna for $8.25.

Leading up to, and during the worlds, I shall be eating nothing else.

I will bring a esky full of them with me on the 1000km drive down to belmont.

Anyone want me to bring them some?

It's gonna be windy.

I am taking orders.

Bootnote: Factory outlet shops sell defective, expired or excessive supplies of product.

Therefore there is something wrong with the above.

However you may also ask, what is right about it.

what would tucker do?

2010-11-30T11:53:00.003+10:00

On Saturday, Peter, my brother and good friend of teh bloog turns a quarter of a century old. We decide to celebrate by going to a gig. No known band playing in bris tonight except kidney thieves. That’s the gothic industrial dance act right? Played something from the queen of the damned soundtrack? They are on the bill for MENAGERIE 2010 feat. The Kidney Thieves + Tin Can Radio + Slimey Things + Pirate + Greenthief. $15 cover charge – thats like 3 dollars a band = value char-ching. This is what happened.

19:01 - load up on dirty bird – gonna be a long night

19:24 - teh valley smells of arse.

19:29 - While outside the globe Peter antagonizes a skinhead in a stoke city jersey. He leers at us. We make a break for the Globe Theatre. Skinhead is afraid of culture – or knows what awaits us.

19:31 - Inside the globe. Resembles a cinema stripped bare with a stage instead of a screen. Nice layout, everyone can sit to watch the support acts so you can bob your head along with minimal exertion. Except for some loon with dreadlocks who is jumping about like green ants have crawled up his arse even without music playing. We consider telling him he’s retarded but fear getting whipped by knotty dreads.

19:45 - Greensthief start playing. They rock. I have forgotten how good live music is.
19:46 - Greensthief start singing
19:47 - Greensthief should stop singing.
20:31 - Greensthief conclude set with a suggestion to the assembled mob (not around 12 peeps) that we buy their $5 album. I’d rather snort $5 of wizzfizz.

20:39 - Thought of wizzfizz makes me thirsty and crave caffeine. Ask barmaid for two Red Bulls. Get two generic, overpriced energy drinks. “Just as good as red bull but without the taurine aftertaste”. Féin interest cause she has a cute smile.

20:43 - frontman of Pirate appears bearing a saxophone with pickup. Plugs it into amp and smoke appears. Visions of burning saxophonist spring to mind. Hilarity ensues.

20:44 - Smoke actually coming from an anaemic smoke machine. Frontman tries out his sax+fuzz box combo – hilarity does not ensue. They begin to play soon after.

21:11 - Set highlight – drummer plays a complex 3 against 4 pattern which is incredible. Guitar bass and sax play something...anything... trying to hold on to the beat.

21:26 - Third band, third saxapone. We check a blog post regarding the gig. Turns out its ‘progressive night’ at The Globe. Given the way this gig is rolling out we begin to wonder if the kidney thieves are not THE kidney thieves.

21:43 - Slimey Things play ‘when household appliances attack’ woo!
21:48 - Slimey Things play ‘White goods off destiny’ woo!

21:54 - an ironing board is sighted on its way back stage. Slimey Things make some remark about their ‘imperial ironing concubines’. Wish they would pay more attention to our entertainment than their laundry. Slimey Things conclude set telling us “Tin Can Radio will be better”.

22:03 - Go back to see cute bar girl again. Many others have same idea. Get serve by some random wench instead thus wasting another $9 on energy drinks. Now have spent more on drinks than we have on the bands.

22:30 - roadie in a pedo bear shirt and a bass player dressed as Jesus - this is going to be good.

22:49 - Tin Can Radio play like runaway train - teh tempo is outta control! But very trippy and cool

23:05 - Jesus's dancing puts his tight white pants at serious risk of splitting

23:09 - cop an eyeful of cock interlaced with bands rear-projected graphics

23:14 - inevitable happens – Jesus’s pants split midstance – another eye full of cock. He continues on in coke fuelled fury unabashed.

23:15 - other inevitable happens. Douches sitting uphill of us, shocked by second cock of the set, knock over whole jug of beer. Pours downhill between Peter and I before soaking into the pants of a drunk chick sitting in front of us. She jumps up and yells at us. we point to the trail of beer. She leaves. Tin Can Radio finish their set.

23:28 - A saxaphone stand appeared. Surely not a fourth one of the evening.
23:29 - False alarm - just a guitar stand.

23:38 - Kidney theives’ roadie is fat and wears a warhammer tshirt. Much more professional. maybe this is real kid thieves after all?

23:47 - Four sets of dreadlocks now on the stage. Very metal!
23:48 - Fifth member has no dreads and plays a sax and glockenspiel. Not very metal. And no sign of the lead songstress. I think we have been deceived.

23:49 - Band begins. Clearly not who we were expecting or hoping for. Aren’t their laws prohibiting this form of blatant misrepresentation? We didn’t part with our $3 to hear this progressive trot. Now very angry. Box office staff to too stoned to care. Contemplate what would tucker do? Return to heckle band.

23:55 - Lead singer starts swinging mic like a tiny flail. Hits own head with mike. Makes a satisfying percussive thud. Not professional. Wouldn't happen to real kidney thieves.

23:59 - Drummer dumming without shirt and with mouth open irritates.

00:04 - Frontman asks “Are you annoyed by retorical questions?” Attempt at wit irritates further

00:13 - Play Faith No More’s Epic. Crowd goes off. Should stick to covers

00:25 - Set concludes. Band try to hide stage right trying to beg for an encore. Crowd complies half-heartedly.

00:26 - Band say they are allowed to play one more song if we all leave the venue by midnight. But they are willing to catch up with us afterwards outside over a cigarette. We decide to call it a night instead.

Hat-trick!

2010-11-25T16:49:00.004+10:00

Finished in 3 days the way this is going... ;)

http://www.brisbanetimes.com.au/sport/cricket/siddle-hattrick-rocks-england-20101125-187zw.html

Another wicket just fell, now 9-254. Wouldn't want to be a pom...m4rkla, do you identify as one for cricket purposes?

OOHH SHIT! No you didn't!

Luka's Lister Boom

2010-11-24T20:32:00.008+10:00

For anyone interested in the merits or otherwise of Luka's boom I present the following. Be warned, it was done in about 10 mins while I was having lunch at work so it is a bit simplified...

150kg vertical leech load
100 diameter thin wall steel boom
10mm round bar steel vang
20ish mm round bar "spreader"
2.5m boom
400mm gooseneck to vang take-off

Conventional Boom

Bending Moment

Deflection = 14.5mm

Luka Boom Arrangement

Bending Moment

Deflection = 13.2mm

A little over a tonne of tension in the vang in the conventional arrangement and a little under a tonne for the Luka setup.

Is it worth the complexity?

wing rule idea

2010-11-22T10:18:00.002+10:00

remove the single sail condition.
make all masts, booms, sails and wings (essentially everything about the mast base) count into 'profile area'.
Restrict 'profile area to 8.44m2 or whatever its supposed to be at the moment.
Add an upper limit to the 'box rule' measured from deepest point to top of rig.

If this results in people building multiple high aspect ratio rigs then so be it as long as it is faster round the course.

nick in teh boat

2010-11-20T20:39:00.002+10:00

Wanted

2010-11-16T11:57:00.005+10:00

Any internationals want to avoid return shipping costs by selling me their boat after the worlds? Probably asking a bit late now but I'll put it out there anyway.

Oh, and Markla would like to buy some skill. Preferrably before the worlds. Bora or Adam may have some skill they won't need with their rumoured speed advantage. Cash it in!

PS. Did I see correctly, two wings going into the US container?

SLINO Design Files

2010-11-14T20:54:00.024+10:00

Please Note:
I am publishing this information as a personal reference only. If you chose to replicate it, it is at your own risk. This information carries no warranty and has not been thoroughly thought through or engineered. Building and sailing a moth to this design could seriously hurt you and/or cost you a lot of money and/or cause emotional damage.

If you do attempt to replicate derivate from this information please send me an email – I am always interested to see where this design leads. (mr.markla@gmail.com)

See Also:
http://perverted-moth.blogspot.com/2009/01/new-moth-design.html

Documents and Calculations
SL2-A1-01A - Drawing and Document List
SL2-A1-02A - SLINO Build Sequence
SL2-A1-03 - Parts List
SL2-B1-01 - Weight Estimate
SL2-B2-01 - Table of Hydrostatics
SL2-B2-02 - Resistance Prediction

Drawings
SL2-C1-01 Side Profile Drawing
SL2-C1-02A - General Arrangement

SL2-D1-01A - Hull Lines Drawing

SL2-E1-01A - Hull Construction Drawing
SL2-E1-02__04A - Hull Construction Details
SL2-E2-01__02A - Centreboard Construction Drawing
SL2-E3-01 Stem and Transom Lug Construction Details
SL2-E4-01 Wing Mounts Construction Details

SL2-F1-01A - Wing Assembly
SL2-F2-01A - Gantry Construction Drawing
SL2-F3-01A - Spreader Construction Drawing
SL2-F4-01A - Running Rigging Arrangement
SL2-F5-01__02A - Cradle Arrangement

SL2-G1-01A - Control System Arrangement
SL2-G1-02A - Control System Parts

SL2-H1-01A - Hull Jig Assembly
SL2-H1-02A - Deck Jig Assembly
SL2-H1-03A - Foredeck Jig Modification

SL2-I1-01A - Carbon Cut File (1)
SL2-I1-02A - Carbon Cut File (2)
SL2-I2-01A - MDF Cut File (1)
SL2-I2-02A - MDF Cut File (2)
SL2-I3-01A - Hull Panel Marking
SL2-I3-02A - Deck Panel Marking

Rhino Models
All models have the same zero point, so you can import (or worksession) the components into a single file.
SL2-R1-01A - Hull Construction
SL2-R1-02A - Hull Jig
SL2-R1-03A - Wings

SL2-R2-01A - Centreboard

SL2-R3-01A - Rudder

SL2-R4-01A - Control System

SL2-R5-01A - Wing Sail

SL2-R9-01A - Cradle

Weather at Belmont

2010-10-21T12:54:00.004+10:00

While I am loathed to average and average, the above is the average of the wind speed at the 3 closest weather stations at 9am and 3pm.

Make of it what you want.

Original spreadsheet here.

Data found here.

Ride Your Bike

2010-10-06T21:32:00.009+10:00

Markla and I have been doing a fair bit of mountain biking as fitness for the mothing. This weekend we're hitting the road though for a 100km charity ride from Brisbane to the Gold Coast. The forecast is fantastic, 20 knots on the nose and rain...yippee...sigh :(
And it's freakin' magpie season! How did I get talked into this?

It seems I haven't commented on the wing sail yet. What little I've seen looks like a very good implementation. Still a bit nervous/dubious about its durability but that can only be proven one way or the other over time. I hope it holds together and is a successful new addition to moth development because I can't wait to start building one...although still want to work on the transportability issue.

SLINO is back together with a couple of mods...nothing that hasn't been implemented by others previously though; a Lister lever (of some description) and a tension linkage system. We felt the tension system was easier to implement and trouble shoot than the pushrod, especially with temperamental foils. The main foil got a coat of paint and a fine wet and dry so is looking considerably better than before. If the Lister level doesn't "Chernobyl", the rudder hinge will be locked off and faired to reduce drag, maybe even get a bit of a shortening of the span. There were some annoying issues with the pocket luff material of the North sail, but that has been given a work over by the local sail maker. Also trying to get the rig right, we felt the mast was not bending correctly so have played with the spreaders, they're a fair bit closer to the mach2 geometry now.

And who is NZL 3315? It appears you've gotten a slightly out-of-place photo on the interwebs...

http://www.surtees.co.nz/home.aspx
(Not associated with this company, just found it randomly.)

4 – Accident With Local Consequences / steve mothing

2010-08-29T18:31:00.006+10:00

there was an unnatural amount of dust gathering on boat, and we finally had wind for the first time in months so we tried to take the boat out today. water was the coldest i have ever felt the gold coast.

session finished 20mins later after I chernobylled another gantry and push rod.

nick took a short vid of steve sailing:

Click me for more photos of Steve.

spreader construction booring.

2010-08-09T08:47:00.004+10:00

while the world is ablaze with wing rigs, I just did a booring sketch woot to answer the question below.

Hi Mark,

...The cut file you provided included spreaders, but judging from your email you haven’t converted these into a finished product previously? My plan is to tip the spreaders with glass to stop the wear from the stays, and to add uni down the sides to cover the core and to give it some more strength. The Bladerider spreaders have a protrusion on the spreaders that fits into the fitting on the mast that you sent a photo of. I’ll search in the Ronstan catalogue for something similar to the fitting that John Illet uses on his spreaders, but in the absence of a ready made solution, I’ll just cast something in glass....

Yeah, I had every intention of making myself carbon spreaders, but I had an alloy set lying about and I have been using them ever since.
The cabon cut file for the spreaders is still sitting in the garage and may get finished some day.

Attached is a drawing about how I was going to do it.
The key is:

Remove the core from the tips of the spreaders.
Lay up some solid fiberglass (not carbon - glass is harder wearing, alternating passes of double bias or woven roving is ideal) plate to 5mm thick
Cut the fiberglass plate to shapes that will fit inside the decored area.
Glue the fibreglass plate in and then lay some 200 uni carbon (UD-C) over the top of the cut part over the length of the spreader arms.
The spreader base can be made the same way, cut an E glass part that is approx 60x20, with a radius and a pin hole where it will attach to the mast.
The UD-C should lap over the top of the protruding part of the E Glass plate.
Ronstan part is RF917 with the pulley drilled out

I haven't tested this laminate yet, but seeing how light on the prowler spreaders are I think it should work. As soon as the UD-C has cured you should have a good idea if it is strong enough.

Cheers

Mark.

Ski Trip Bazinga!

2010-07-30T19:14:00.002+10:00

The gang are off for a ski trip to NZ, specifically Mt Ruapehu, starting this weekend!

Markla and Nessie should be taxiing now with the rest of us stragglers coming in waves tomorrow.

Wish us luck and no broken bones...

wings

2010-07-30T07:40:00.005+10:00

i did up a drawing of the wings on my boat for reference to the new slino. this drawing is available thru my google docs (i will gradually transfer all of my drawings to this site - still not sure where to put the rhino model and cad files, for now these can be emailed on request).

at the moment I am running aluminium wings as noted on the drawing. i also did some calcs for equivilent carbon wings (based on CST products):

76x1.27 Aluminium (EI 14.37kN/m2)
*ID63x1.8 Carbon

50x1.6 Aluminium (EI 4.92kN/m2)
*ID35x2.5 Carbon
ID40.4x2 Carbon
ID44.7x1.8 Carbon
ID47.2x1.5 Carbon

40x1.6 Aluminium (EI 2.46kN/m2)
ID32x1.5 Carbon
*ID30x12.6x1.5 Ellipse Carbon

As drawn in aluminium the wings would be approx 7.47kg
Using the alternative carbon sections marked with * above gets 4.72kg

A bugetary price for aluminium tubes is $266, for carbon $1873 (again using the * sections)

new slino

2010-07-28T08:33:00.004+10:00

i can't remember when but I sold the jig-mould-thing to a guy in melbourne and gave him some cut files so he could build a boat like mine. i just got some photos of his progress and they are attached.

gotta love the stealthy look.

more details as they become available.

plug 2

2010-06-02T09:33:00.005+10:00

while in the mood for plugging reasonable looking companies I can across a guy (when they let me out of my exhibit) at the Sanctuary Cove Boat Show selling this stuff:

Hull speed super glide
http://www.hullspeed.us/hullspeed_products.asp#superglide

It looked rather neat. Very easy to apply, just use one of these basic spray bottles to apply to the surface and then give a circular wipe with a clean white rag. Being a 2 part system it will cure on the foil surface and is good for up to 3 months. It does not need to be buffed like a polish system, just wiped into a thin film.

It looks ideal for foils and apparently olympic dinghy teams are using it. Anyone else tried it?

From Phil @ Dulon...
$195 per quart kit and that would last you until you are grey and unable to race moths I should think!

Rapid Prototype

2010-06-01T20:33:00.005+10:00

For the last few weeks I've had a Bladerider RX to play with. It has undergone a little bit of minor damage (standard fare for a moth) including busting a plastic spreader base fitting. With no success reaching BR, I tried my hand at something I've wanted to do for awhile...RAPID PROTOTYPING.

Some basic rhino modelling and a couple of ridiculous quotes later ($100s), shapeways came to the rescue. $11.70 for the part, but minimum order of $25(ish) and 10 days later my two spreader end replacements have arrived!

The broken spreader end, the model and the final part.

The material is what they call white, strong and flexible and now that it is in my hand, it seems just about right.

So if you've got no time, tools or skillz for building some small fiddly bit, give rapid prototyping a go. If you've got no modelling skillz, let me know and I can probably whip something together for you (within reason).

Must resist the urge to pimp the boat, but if there is enough interest for certain items I may consider stocking some bits and pieces.

Aside - They can rp metal, glass and sandstone as well!!! Unbelievable stuff!

Disclaimer - I have no affiliation with shapeways, my experience is that their service and price have been really good, so they deserve a plug.

Wing Design Concepts

2010-05-23T11:25:00.007+10:00

The moth has been and should continue to be a development class so the natural next progression is towards a better aero package.

It's probably no surprise to learn that we have been designing a wing sail for a moth...as we suspect a lot of other mothies have been doing. They've been around for a while on C-class cats and seem to work well. Below are a couple of notes for developing a wing rig for a moth:

Requirements

Weight - tricky one, extra weight can be acceptable if the boat is faster around the course. consult VPP
Watertightness - gotta be able to right it after a capsize
Survivability - not essential but handy. if repairability is high not as important
Repairability - if it breaks, must be easy to repair in a boat park
Better Performance - waste of time otherwise, although it would be cool, consult VPP and mojo
Transportability - not all of us can afford to pay ppl to look after our boat 24/7. break down to either component parts or easy to fit in a regular trailer. 2x2 piece option may work
Cool - can't look too shabby
Cost - preliminary costings indicate that unless it is a full carbon monolith, the cost shouldn't be too extreme compared with a traditional rig (mast, stays, sail and development of these). mods to the hull are another matter, particularly if the requirement is to switch back to conventional configuration quickly and easily.
Arrangement - A stay-less wing rig seems like the best option on a moth. On shore handling and durability of the rig are the primary concerns with stays. This isn't locked in stone though.
Construction - Good if it can be homebuilt without special requirements (space, tools, etc).

Our revisions so far

full composite - likely to be too heavy and expensive
composite and heat shrink - not a bad solution in terms of weight and cost, used by C-Class et al ie proven construction, transport is a killer
sock over frames - with spinnaker clothe, light, cheap, not likely to be water tight and durability concerns
styrofoam modules - cheap, heavy, don't capsize on a petrol slick, UV issues, water absorption issues.
composite and heat shrink modules - demountable for better transport, a bit heavy, easy(ish) to build
composite and heat shrink nested modules - easily transportable, not too heavy, but stiffness might be an issue without careful designt. Nesting refers to the open bottom which slips over the module below when rigged. All modules nest together like a russian doll for transport.
composite and model foam nested modules - easily transportable, not too heavy, easily repairable, cheap enough, better stiffness than with heat shrink, free flooding but also free draining.

Option 5 (frames top and bottom)

Option 6 (note open bottom, glass leading and trailing edges shown)

The spar would just be a square carbon beam, nothing fancy and easy for a home builder with experience.

Note that we haven't even gone into performance and shape requirements yet, it is believed construction is the biggest hurdle to overcome.

Will it be feasible? Can we be bothered to build one along with the hull and beam modifications?

You'll just have to wait and see...or do it yourself...

QLD States

2010-04-22T08:18:00.008+10:00

QLD moth states over 17-18 April.
Probably the first regatta where the foilers leaked more than the scows.
Fleet was 3x M2, 1x BR RX, 1x BR x8, 1x Assassin, 1x Home built foiler, 1x LR HT, 5ish scows.

More photos here, some are good.

I got back from a trip to china on the 17th, was hoping to make it out on the 18th but was struck down with teh ills, so i caught a ride on a rescue boat instead.

Perfect weather, nice easy 13kts or so when i was there on teh sunday. Appartently the saturday was much windier with some short chop.

Final foiler results:
1. Brent Pearson
2. Sandy Cavill
3. Steve Sherring

Final results for scows:
1. Mick Kohler
2. Pete Williamson
3. Mike Willcocks

Just one skiff, Nick Taylor.

In other news Nick has found an underloved BR RX and is giving it some loving till its sold. w00t! training partner.

nsw states

2010-04-18T19:02:00.004+10:00

great place to sail.

my boat didn't go upwind, just reached back and forth.
don't know how to fix it yet - should be obvious with more practise.

some advice from other people were:
- improve foil finish
- bin the foils and buy new ones
- don't use 40mm cams on 50mm
- wand too far offset from CL
- use more vang

a repair of the push rod rebroke during the 5th race with 3 to go. Nick and I managed to jury rig a tension system and so the boat was back on the water for the final day.

boat at the rock? i thought it was bigger.

Sucker for a Pretty Face

2010-04-13T11:36:00.002+10:00

Bladerider RX used less than 10 times.
Excellent condition.
$15,000 asking price
Located in Brisbane

Anna.Patterson ( a t )
goodman.com

Stress Less Refit

2010-03-25T22:34:00.004+10:00

While Markla is well underway with boat handling and getting up to speed in his boat, I still don't have a boat of my own. I've been umming and aarring about the viable options; buy second-hand or rebuild an old boat with second-hand gear (already have access to a very narrow shell lying around). Ultimately I would love to buy a new boat and not worry about getting sticky fingers, but I just can't see the value in them for a relative newbie.

Decisions, decisions...

The bare hull shell that was stress less is sitting at Markla's parents place gathering dust and snakes. As part of determining whether it is feasible to rebuild it, I present an early rendering. Current thinking is to move towards socketed beams rather than what's shown. Maybe something similar to whisper but without the freestanding rig, a stump stepped mast perhaps. The stress less hull is very narrow but relatively light so I see no reason it can't be converted to a foiler. It will need some carbon reinforcing from mast to cb case though. The biggest problem is finding a place to do the refit.

Foils are also an issue. Markla has been investigating the design for a home-built set and we've got heaps of ideas for building them relatively easily. More on that later though.

Lots to think about...

Moth Tattoo

2010-03-22T21:37:00.000+10:00

Who thinks markla should get a moth tattoo?
One or the other of these, or combined as shown would be good. I reckon on the shoulder blade would be best.

camber control

2010-03-17T11:45:00.004+10:00

Heard Amac interview talking about how long it takes to trim sail in light weather conditions, i thought this might help.

Glue this device to your deck to provide 100mm throw on the middle control line with a total purchase of 24:1.

Everything is shown to scale.

Assuming vang of 16:1, 6:1 for down haul and 2:1 for outhaul so at 24:1 I am matching the current amount of purchase. With larger diameter rope with an easier pull the overall effort for skipper should be less.

Two features to make it easy to adjust:

Series of holes in lever, move the take off up the lever to increase the throw of a particualr system
Turnbuckle on each control line to set the zero point of each system.

I would imagine these two settings would be changed to suit the conditions or sail chosen.

It doesn't need to be a single module (could be split into cleat base and lever base) but this way the loads are contained within it rather than applying bending moments to the deck.

Grey is carbon, cream is 80kg foam.

Carbon is moulded from a bent sheet metal mould. Port and stbd halves moulded up, glued to foam and a bridging laminate links the two cleat bases.

I could almost imaging someone in a light weather race holding the mainsheet (blocked out) in his tiller hand and working this sail camber control upwind.

Tsunami Warning!

2010-02-27T23:17:00.002+10:00

This is not a drill.

After the earthquake in Chile, there is now a tsunami warning.

http://www.bom.gov.au/tsunami/

A little useless at this late hour, but might as well try to spread the word.

Starcraft II

2010-02-27T15:30:00.003+10:00

http://www.wired.com/gamelife/2010/02/starcraft-ii-2/

looks like my mothing skills and sleep patterns may suffer in a few months.

elephant

2010-02-16T15:50:00.000+10:00

new poll to address teh elephant in teh room...

Walk of Shame

2010-02-14T12:09:00.008+10:00

It was me 2 weeks ago and Markla this week. This time however, a bit more damage occurred after foiling into the shallows. The strut has cracked right down the leading edge and its torsional stiffness has pretty much gone, making it unmanageable in flight. Plans are afoot for repairing them.

Markla alleges he was in the channel at the time however the pure pwnage of the foil tells a different story. The approx location of teh catastrophe is below.

It was a long walk back to deep water.

follow up

2010-02-10T15:03:00.003+10:00

follow up to this...

approx camera location

house boats started here

house boats ended here

good time to be in repair/refit

2010-02-09T20:02:00.003+10:00

NOT MY VIDEO!
this is what 400mm rain in less than 24hrs will do...

My local stomping ground.
Wind looks good for the weekend.
It will be interesting to see how much rubbich is in teh sea.

lifting line theory

2010-02-03T08:27:00.002+10:00

for a while i have been trying to understand the lifting line theory. this has many benefits over the basic aspect ratio corrections for the calculation of CL and CDi including:

Non-elliptical planforms
Twisted sections (AoA varies along span)
Section changes along span
Wing tips (probably - see below)

it took me a while to work it all out because i didn't want to pay for a textbook and most of the internet references i found would either:

have no nomenclature
have errors
after stating the method equations declare the solution too hard
give the results for a single (not very useful) case only
not have a worked example to compare results to.
obviously every website has minor differences in nomenclature and assumptions

Yesterday I had an epiphany and remembered what a Fourier series was and the pieces fell into place and allowed me finally understand what was going on. I won't repeat the procedure here but I will give 3 useful links for people who do want to attempt it themselves.

Best description of method
Example to compare your results to
Simple Matlab code

A few notes on solving Fourier terms:

In the matlab code the line 'a=b\rhs' is matrix maths and means [An] = [b]^-1 . [RHS]
Look up MMULT and MINVERSE in Excel help, makes solving linear equations sooo easy and makes anyone who has coded row reduction methods in excel feel stupid.

I can supply my spreadsheet by email if anyone is interested.

Note on wingtips analysis:

I am not sure whether this is valid or not yet. Probably valid enough for anyone satisfied with a Lifting-Line theory result.

Design a wing with wingtips
Fold these wingtips down so they are in plane with the wing, adding to its span
Twist the wingtips so that they produce zero lift, independent of the wings AoA

gearing

2010-01-28T11:58:00.002+10:00

click me.

easier to adjust than M2.
if your bellend isn't inside the CB

First

2010-01-26T20:49:00.003+10:00

Guess who was first to do a foiling gybe on SLINO...?

Guess who is owed a rum...?

Started out with 20 knots today so decided on the chicken rig. Markla was first but had a couple of big crashes early with a tangled wand not working properly. Ended up being about 12 knots by the time we were off the water. The chicken rig still faired reasonably well in the lighter wind except for trying to stay deep downwind, that was a bit of an effort but to be expected.

Narkla hit bottom, hard, while going into a tack on foils. Water was only about thigh deep...doh! No major damage (slight chip on one tip) but these foils of Al's are really taking a beating well. They've hit bottom at pace a number of times. Bit of a drag to get back to deeper water only to have some shunt jetskier spray me from within a boat length, TOOL!

Still lacking a bit of height so the plan is to add a little AOA to the mainfoil and see what happens.

two videos

2010-01-25T20:55:00.006+10:00

don't watch them
i don't watch yours
moth videos are now boring

me trying to gybe
and me failing into into the poontoon
and nick failing fend me from the poontoon
and nick failing to film me crashing into the poontoon

n4rkla sailing a bit

lots of training recently

one interesting mod, in these videos we have removed the shockcord that self-centres the rudders. the boat is much more vibrant to sail without the shockchord. it is easier to sail thru the maneuvers too. Alan mentioned that the fast australians are going back to shockcord on the rudders to help them fack. even so i think it will be a while before i put it back on

worth noting that the boat crashed with a very loud bang (1:35 in first vid), but there is not a sign of damage. i didn't even bring it back to shore afterwards.

nationals results

2010-01-06T10:02:00.002+10:00

Go Alan!

Something strange is happening (lotta bad links) with the imoth-wa website but i did find some results here:
http://nsigns.com.au/moth/results/
Just click any of the date modifieds after 1.Jan.10.

This appears to be more of a workaround than something right so I don't know how long the link will work for.

Idiot Swing

2009-12-24T14:58:00.009+10:00

Take one charter boat, a spare spinnaker halyard and some clowns fired up on rum...The pictures speak for themselves really...some extras added for amusement also...

What's that boat in my mouth?

2009-12-24T13:49:00.006+10:00

Had an idea for a big boat (well bigger than a moth). It's a variation of someone elses idea for a small sports boat which used a straight horizontal board that could be shifted sideways to produce lift on the leeward side of the hull. This would increase righting moment and provide a little vertical lift. The problem I see with that idea is that it is very close to the surface when the boat is flat and produces a negative side force when heeled. My idea puts the foils deeper in the water and allows it to be rotated to nearly horizontal no matter the heel angle.

The case mechanism could be a little tricky if the board isn't circular, but some carefully placed hinges, guides and flexible water barriers should do the trick.

Someone else has probably had this idea too, but thought I'd share it anyway.

The hull is one I prepared earlier.

http://www.youtube.com/watch?v=CG3gQ_I1L3E
http://www.youtube.com/watch?v=886H3CXYR5o
It's the future...maybe...

Hopefully this brings us back in line with our usual standard of posts after marklas last couple of (really) weird ones.

trifoils

2009-12-21T07:34:00.002+10:00

curious about trifoils?

hydroptere is my desktop.

Route WRC (or ply) into pressure/suction sides.

Use a bricklaying style to assemble routed pieces into one long lenght, long enuf to do both foils

One Wrap in WR carbon.

~~Screen with a fairing template along entire length.~~ Also route a female shape for the pressure and suction sides, cover in brown tape and use as a mould for the bog. This doesn't have to be the length of the whole job, just the immersed length of one hydrofoil side.
chop lenght into parts as required and secondary bond together.
use with my existing T foil.

(doesn't include holiday my parernts so I can use their garage again)

Wind is gay

2009-12-20T09:38:00.001+10:00

schwinge!

2009-12-18T11:41:00.004+10:00

http://www.schwinge.co.uk/

The Architecture of the Tetrahedron Super Yacht.

The design is instigated by the re-thinking of the form, superstructure and propulsion of the modern super-yacht into a radically simple enclosure and an elevated mode of travel above the water line.

The superstructure form is reduced to the absolute geometry of a Tetrahedron. A three-based pyramid consisting of 4 faces and 6 leading edges provides fundamental stability and enclosure. Its form produces a pure, precise, logical and mathematical ‘roof’ for which to connect to the hull assembly. Generally, simple forms are not known in ship and motor yacht construction through restrictions in ocean-going hull design.

Ocean Flying Triangle

The Tetrahedron would have the appearance at high-speed of ‘levitating’ over the water: a boat that can fly. This is produced by a HYSWAS hull - A Hydrofoil Small Waterplane Area Ship - that is comprised of a single retractable vertical strut onto a single submerged ‘torpedo’ hull. The vessel will lift out of the water at speed on side-mounted adjustable hydrofoils.

This hull form has two working ‘waterlines’ for its operation. At low speed the Tetrahedron sits gently onto three underbelly hulls. At high-speed the hydrofoils rotate on the lower submerged hull, causing the effect of mysteriously raising the triangle out of the water.

The concept design of this HYSWAS craft is based upon an existing hull design which has been developed by several companies, notably the Maritime Applied Physics Corporation in America, and has been proven by their technology demonstrator - ‘The Quest’ - in 1995.

An auto-pilot ‘fly-by-light’ system from the aviation industry would take control of difficult roll forces and maintain ‘foil bourne’ speed. This would also control pitch and heave.

Long distances are achievable with reduced out-of-water drag and stormy ocean conditions would incur virtually no slamming. Improved efficiency is driven by elevated hydrofoil propulsion and would be an inherent performance benefit of this type of design.

Long distance, smooth travel through rough water at high speed: the key performance attributes of this new motor yacht design.

Sent

2009-12-10T09:07:00.003+10:00

Well that was a great day of mothing. Good wind, good height control, reasonable endurance (well compared with all previous attempts), no breakages and plenty of speed. Unfortunately the GPS is busted so no top speeds to tell of.

Markla was lucky to get three days of mothing in last week and it really showed on Sunday. His windward heel looked pretty much spot on with mainsheet and hiking skillz working well together to keep it all smooth. It sounds obvious but getting the basics right on a moth is tricky as well as important. He tried a couple of gybes too, first two were far enough but he didn't move across quick enough, third was an over correction and didn't go far enough around before trying to change sides.

I was nervous about going out because it looked quite windy but after seeing Markla handling the conditions easily and the boat looking very stable on the foils it had to be done. And it was well worth it, upwind was fast and in control, downwind was fast and in control. Paced a cougar cat upwind for a reasonable distance. Tried a gybe but wasn't sending it through far enough or with enough speed. Longest foiling rides I've had by far. The arms and hands gave up first and the quads were sore (but didn't cramp like last time) but the hamstrings really weren't used to sitting on the wing bar that long and hard and were the sorest on Monday and Tuesday.

The internal vang works now that it doesn't twist up inside the boom, only problem is that the line is a little too small and the cleats don't hold it when fully cranked.

Still a couple of jury rigged repairs to finalise; the pushrod is held together with grey sticky weld, wand paddle is huge and heavy (it's a resin infused 50mm paint brush taped to the wand, the wand will bounce up on a wave and without plenty of shock-cord it comes down very slowly which is affecting ride height a little), the gunwale edges under the heavily loaded lacings are cracked (markla is still debating which solution to implement).

I busted my ankle at touch last night, can't put any weight on it, so won't be sailing this weekend. Bugger, was looking forward to it.

Whitsunday Trip

2009-11-10T11:54:00.002+10:00

Not really a lot to say except that it was near perfect. No major incidents, lost track of the days, didn't get too sunburnt, saw the sights...perfect.

Next trip for markla and I is this weekend, road trip down the east coast of Australia to deliver my cat to the new owner in Canberra. Rum, hookers and blow here we come!

Rock Star Revisited

2009-10-16T11:44:00.001+10:00

Alan (light wind God) Goddard is being flown in over the weekend as test pilot of the SLINO. With a national championships heat win under his belt, it will be interesting to see what he makes of it...

nuff said

2009-10-16T07:42:00.002+10:00

wtf? see here...

Whitsunday's Bareboat Charter

2009-10-15T14:52:00.003+10:00

A gang of would-be adventurers will be heading to Airlie Beach Sunday and Monday to begin what will go down in history as either the greatest sailing voyage in history or the greatest sailing fail to befall the Whitsunday's. Fat, Al , Markla, Nessie, Ninja and Ncik/Narkla are the instigators/perpetrators. Frivolity or felony will ensue and we'll be sure to update the mothosphere upon our return if not during the event.

NameD

2009-10-09T13:29:00.010+10:00

It's been awhile but it appears democracy has prevailed. After numerous recounts, legal rangliing and court orders, the name has finally been set in stone....lets hear it for....drum roll please....

LEEERRROOOYYY JEEEEEENNKINNS!!!

Thanks to everyone who voted and congratulations to the write-ins, without your support this momentous...ah...moment...would never have been achieved. Thank you.

This does't mean you won't see this craft appear under other names such as "this.is.SPARTA!", "mushroom mushroom" or "bon3r pirate" but atleast we can put something new in the pole (cough-poll-cough...learn to spell if you're going to h4x0r my posts markla (in joke with my mother f00l - M.) (((whatever)))) section.

Incedentially we have also recently discovered that Slino is Slovenian for, well I'll let you find out...

The urban dictionary also has an interesting definition.

Loosing Less

2009-10-04T19:18:00.004+10:00

a club championship race today in perfect breeze. A consistant SE 18kts gusting to 20. The first race in foiling wind I have finished and I seem to be loosing by less.

I got the boat foiling nicely upwind but still got no idea which angle to sail down wind. Whenever I try to hot it up and bear away I loose the pressure in the rig and it becomes rather unstable in heel.

Foiling in amongst a fleet is so much fun. Slotting into gaps between a chain if optmists while doing 3-4 times their speed is extrordinary.

Narkla and I took it out in a gusty westerly yesterday. Patchy with gusts up to 18. Narkla has set a new best speed on the boat of 18.6kts and claims, on his first decent sail to have pulled off a foil gybe and a fast foil touch foil tack. I wouldn't know I was at the crab island bar.

My gps is boned. The foretrex 101 battery compartment has leaked and the terminals are very corroded. I have heard others have had this problem. It's a pity it's a great unit and cheap.

Insurance

2009-09-20T17:32:00.002+10:00

Time for some third party indemnity I think.

Today was sprint races. First race was 5kts breeze and 2.5kts current. I hit a lazer, a 420, a 29er, 3 jettys, a sandbank, the bottom mark and got my rudder foil tangled on the top mark. Then my coke drifted away.

I skipped that race and the next and joined the last one. Managed to get it flying in 10kts of breeze which is a new best.

first

2009-09-12T20:05:00.002+10:00

the only question is just how much purchase is inside this boom of doom?

can't...hold...it...in

2009-09-03T17:46:00.008+10:00

we've designed a wand linkage system incorporating a cam on the wand axle (just a quick screen shot, parts to come) and also built a vang that sits inside the boom with just one dyneema rope coming out of the bottom to the king post. more pictures to come.

aahhh, I've been holding that in for awhile...whether those two items work or not is another matter, time will tell...it may all just be ill-conceived tinkering...

well, that was a secret fail

boatwork

2009-08-30T09:59:00.006+10:00

I am glad all this reposting has stopped. i did put a comment to that effect foilermoth but it didn't appear to get past moderation. i feel oppressed lol.

a bit of boat work going on atm which is no excuse to not bloog really. two weeks to go till the start of my season and time to do the first real servicing session on my boat since it was built. all in all it has held up will for an amateur home build... so far...

the list of maintenance/mod jobs:

replace 6mm fibreglass push rod with a 10x1 carbon pultrusion (50% comp.)
fit a "dial" to the push rod (50% comp.)
repair some cracking in the deck edge (80% comp.)
replace tramp lacing (0% comp.)
replace deck grip with foam (0% comp.)
affix the mast ram with epoxy+glue powder rather than the duct tape and sikflex (100% comp.)
tramps to sail maker to shorten, and add cut outs to moving hiking straps outboard.(0% comp.)
shorten hiking straps (0% comp.)
new boom webbing (0% comp.)
take gantry to sail maker for a monofilm fairing with a velcro pocket (0% comp.)
sail to sail maker to repair batten pockets and recut pocket opening at hounds. (0% comp.)
new vang system, but more on that in a later post - a little secret squirrel, will post when it works. (40% comp.)
New wand to flap linkage system (very secret squirrel till it is actually on the boat and working, we're both a bit excited about it but want to have a working conventional system first).

sailing fitness

2009-08-24T19:28:00.001+10:00

today i got this email from n4rkla:

http://www.sailfitter.com/sailfitter.html

http://sportstrainingblog.com/sailing/sailing-fitness-10-things-you-must-do

regards,

Nick.

i think his meaning is quite clear, despite the message only having two words, one of which being nick. atleast the internet mothing is going well. this post should clock up teh 20kth hit!

Pitchpoles - Help

2009-08-18T09:01:00.006+10:00

I always thought all of this talk about optimizing gearing was a bit of a wank. Well N4rks and I adjusted the lever off the wand to try making the boat take off sooner. Whatever we did has turned this nice happy docile boat into a angry monster.

I spent the whole day pitch poling and struggling to get downwind in about 16kts of breeze. I probably spent as much time on my side as upright. N4rkla took the folloiwng movies. It shows a number of typical pitchpoles.

Can anyone suggest what is going wrong? With the exception of the last clip it doesn't look like the vessel is flying too high. I'll try to get access to a better video camera for next time I go out.

WARNING: Fake Doug Lord Nude Pix

2009-08-12T07:29:00.005+10:00

With the 2009 moth worlds in full swing, there is a scramble in the moth bloogosphere to get those all important hits. Some of the lowest kind of bloogers are willing to try anything to increase their website traffic. Recently an explicit photograph was leaked into the public domain aledging to be an intimate photograph of Doug Lord from an internet dating site. For some sites, it has become the mainstay of their hits. Be warned, the photograph below is a fake, and any morally compromised bloog asserting it otherwise should be disregarded by the world moth community.

The use of deceitful means to attract unsuspecting visitors has always been present on the internet. If you don't cater to the lowest 2% of the community, that's 2% less hits. While few users would actively search out pornographic images of internet phenomenon that is Doug Lord, links such as “See Doug’s Wand” or “Good Lord! He’s Naked” can arouse curiosity.

A well know mooth blooger, wishing to remain anonomous mentioned recently:
“I think this is a really cheap way of running a blog, just catering to hype and the lowest kind of person. It is a sad reality that there are some bloggers out there who have no shame. I am a real conisuer of internet filth. The reproduction of fake images like this can only be bad for the internet.”

But others are right into the pictures, guenuine or otherwise:
“I can’t get enough of them! DL in the nude! I don’t care if its fake, he is sooo hot.”

The final word goes to our in house internet consultant has the following advice
“Personally I think it is just disgusting and I haven’t downloaded porn since I stocked up 2001, prior to the proliferation of edited images like this. I think it is the only way to be safe from compromised images”.

AC33 and moth worlds

2009-08-06T11:33:00.001+10:00

WOW! Two very anticipated sailing events within the same country within a month of each other!

2010 Dubai Moth Worlds
33rd America's Cup

Who wants support crew?

SLINO 2

2009-07-31T17:34:00.002+10:00

tesaser.

see this site again in about 2 months for a complete design for the above.
will be possible in flat-pack.

gantry material

2009-07-27T21:04:00.005+10:00

this evening I saw the new harry potter movie for the second time in two days. prof. slughorn is a splitting image of a boat builder I have worked with...

karl mentioned on my last post that he thought aluminium would outperform carbon for gantries. I produced the above graph comparing the strength and cost of tubes of carbon, stainless, aluminium and titanium. The catch is only readily available sections were used. The metal tubes were sourced from http://www.onlinemetals.com and carbon came from http://www.carbonfibreexpress.com/.

Each type of tube has two columns. The first is the buckling strength of a length 550mm long (I mentioned in an earlier post that the minimum value for this parameter is 350kg). The second column is the cost of 2475mm of tubes (approx what you need for a gantry). The bottom axis is the weight of the 550mm long tube.

Filament wound carbon tube is the clear winner from the list. The tube pultrusion is next. I am sure I was told pultrusion has off axis material however I think for the marginal cost saving I would still go with the filament wound carbon - a little more robust.

First aluminium comes in at 50% more weight, but that only has a 0.9mm wall. You would probably only be able to glue such tubes together into sockets as the wall is so thin. However it is CHEAP!!! $25 for all the tubes you require. And just as strong as the carbon.

I always struggle to find an application for titanium (outside of high temperature/corrosive environments). This shows it has very similar strength and cost as the carbon, however its high density (4.51g/cc) makes it twice the weight of carbon, even with 50% less wall thickness. Stainless doesn't even get a look in before 3x weight. Rather cheap tho.

I am a little disappointed to see how far along the list my gantry is. But I am told bladerider uses 20x1.6 aluminium so I am slightly lighter than them. If anyone else wants to divulge what they use I will mark them on the graph above too.

3rd gantry / sails 13 and 14

2009-07-20T19:29:00.003+10:00

i should have mentioned my new gantry earlier, it has been on the boat for around 5 sails now. Thanks to those of you who emailed suggestions.

I made a structural model of it at work in beam modelling software. My worst case loadcase was 75kg lift, 7.5kg drag and a lift coefficient of 1.2 on 200mm of rudder 20kts (ie stupit steering).

As most people would expect the highest loaded tubes are the diagonal ones going from lower aft to top forward. On one side the diagonal tube go into compression, on the otherside it will go into tension. The steering load in this tube dominates all other loads so the tension and compression are almost equal at around 350kg. Most materials can handle this direct force, the tube size is governed by buckling limits.

I considered 4 different tube types, all standard sizes.

In stainless steel I could use 19x0.9mm. (I was very surprised and disappointed 12.5x1.2 hit the buckling limit, stainless would have been so bling).
In aluminium I got 16x1.6, I believe this is a smaller section than the bladerider (and cloned BR) gantry.
10x5 RHS carbon pultrusion
12IDx1.5 Carbon tube.

Interestingly the 10x5 RHS turned out to be the lightest option - lighter than tube. I think it would be easier to join too compared to tube. However I have access to some welders, and i don't like sticky so I went for teh aluminium.

No aluminium welder could understand how simple the gantry was and they all quoted me around 20 hours. In anger I drew up the CNC parts below which made the whole gantry self aligning once the 6 tubes were cut to the right length. All that was required was to zap around the perimeter of each CNC part and the thing was assembled. Unfortunately the small, thin tube was still hard to weld, especially to the 4mm CNCed plate, so it still took around 8 hours, 2 pies and a bottle of john walker.

The results are good tho, seams sturdy enough. While I am told all gantries are destined to die, I can take immediate pleasure in having one of the lightest going around.

Sail 13 was a another friday, escaping from work. left work late and missed the wind. Sail 14 was quite a bit more interesting. It was blowing 10kts and I haven't had the boat flying in such light weather. I was surprised how hard i needed to work in such little breeze. I think I was undersheeting and not hiking enough on previous sails. This sail I was making a deliberate effort to pull the main on to 100% and hike out as far as possible. It payed off and the boat regularly flew - well until my weak abs gave in. 14kts boat speed in 10kts breeze = w00tage.

11 / wand / footy / jig / machines

2009-07-16T08:41:00.004+10:00

A little bit of news:

Took boat out on Friday. 11th sail. It was blowing 22+ knots all day. I put my 7sq chicken rig up, and baring one large sustained gust at 21kts the wind remained at around 16kts for the rest of my sail. So I was underpowered most of the time. I recorded the boats top speed so far – 14.7kts over 2 sec just pipping N4rkla’s 14.666 from April. N4rkla took some photos and video, but nothing worth posting.

I have been testing wand response and there is currently a weight at the end of my wand. I figure the inertia might filter out some of the wave responses. During this sail the bungy came loose and the wand was bouncing through its whole range of motion for each cycle of the chop. The boat was bouncing about all over the place. This was hilarious to watch and a rather interesting ride. I was surprised how quick the height can change. Strangely nothing broke despite these uuuge accelerations and the foil stayed in the water. Pulling the bungy back on stabilized everything again. It will be interesting to see where this spring(shockcord)-mass(wand)-dampener(friction) study will lead.

I put the deck on my footy last night. Holes all over the place. I need to drown it in Tarzan’s grip to seal them all up. Might get it sailing this weekend. I will do a full post on the footies later this week.

I have sold the SLINO jig to a bloke in Melbourne. It will be departing shortly. It will be cool to see another one on the water. N4rkla are currently collating our design revisions and will post them shortly. Hopefully before the construction starts on the next one. I will be making the plans and Rhino model freely available on this site (and the world one too if there is additional interest).

I did a site visit of a marine machine shop earlier this week. They have such cool toys. CNC lathes, 6 axis mills, forging capacity. I need to hurry up and finish designing my new foils, but I got so much work on. But to give you an idea of how busy I am, I am writing this at 5:30am with 3 instances of Rhino open each doing a high res render for 3 different clients!!!!11!1!

Cool as ice...pfft

2009-07-13T19:07:00.013+10:00

list of cool moth blogs that is much more accurate than any worlds form guide!

Thanks for the plug, but if you knew the real markla, cool would not be a word associated with him. His penchant for moths and heavy metal pale into insignificance compared to his uncool footy building skills and left handed-ness. Narkla on the other-hand is fuckin’ Fonzi cool! Just ask him…ayyyy!

It is true, after one too many days waiting for the wind to fill markl4 challenged me to a footy building duel, something to muck around with until it's worth heading out on the moth. Needless to say the building part is progressing slowly with the styrene sheet plate hulls finally watertight and keels being built now. One design swing rigs will be built next (with thanks to markl4's sorkplace for supplying mylar printing, little do they know), but we'll do these together because there is a knack to it (I'm a model yachty from long ago, including internet debates with DL about 12 years ago!!! maybe I shouldn't admit to that after being rated the coolest bloog...it's in the past now). Next hull build though, I'm not sure markla should heat cure the hull joins in the oven...styrene is a thermoplastic. Photo of the Fonz footy below, I can't find photos of your Elephant Man m4rkla.

On the IKEA moth front, we're in the process of updating the flat pack to incorporate lessons learnt and cool ideas, discussion to follow...

Disclaimer - N4rkla doesn't have nearly as cool (or thick) hair as The Fonz or womanise quite as much (if only I could)...

Before...
After...

Speaking of cool, how awesome is Alinghi 5! Can't wait to see video of it sailing. The yanks will have their work cutout to beat one of the fastest big multihull teams around. I "did" like the look of DoGzilla and thought it would be a contender, but with its latest mods and A5 now to compare against, it just doesn't do it for me anymore. I hope Larry doesn't take it back to the courtroom, settle it on the water.

business time

2009-07-07T18:29:00.003+10:00

Boat’s odometer is up to 10. Got sick again on Friday afternoon, this time it was blowing 10-20 from due west. Westerlys here are typically patchy and gusty. As I was rigging a number of large bullets came thru being rather intimidating but the max wind speed moderated by the time I hit the water.

The wind was perpendicular to the channel I was sailing in so I got the longest runs to date – 630m – but not very fast. Typically the boat was sailing along level at a constant speed, but as I sailed into a gust the boat would accelerate, fly too high and crash. This is clear from the GPS track below.

I did have a good time and the long runs are very satisfying, but when I got off the water and saw the top speed it was a bit “is that it?!” (14.3kts). Reminded me a bit of this song…

sicky w00t

2009-06-17T19:26:00.003+10:00

There are currently 200 confirmed swine flus in QLD at the moment. Today at 1:30pm I got the sniffles. Acting out of the greater good for my fellow man I quarantined myself.

Totally unrelated, at 1:00pm, as predicted the seabreeze kicked in,15kts from the SE.

By the time I had the had hooked the trailer up my sniffles were gone (an obvious false alarm but you can never be too safe) and proceeded to the yacht club for the boat's 7th sail.

The weather was absolutely perfect. I it was the best sailing experience I can remember. The boat was reasonably easy to get into the air. After a while I was getting the confidence to see how far to windward and down wind I could push it. By the end I was starting every tack on foils. I was surviving 75% of low riding gybes. The closest I got to a foiling gybe was getting to the centre of the boat pointing dead down wind before ditching it.

So things I immediately need to work on.

For most of the day the boat felt really unstable in heel. I think this was all my fault tho - a combination of not moving my body in and out enough, and trying to steer, or sheet my way back to a comfortable heel. I am very surprised how little help sheeting and steering is, especially compared to displacement boats.
I am still not sure how to use the twist on the tillerx. This is compounded by me yet to know which direction to turn it to achieve lift. After the sail I think I need to consider it in terms of "bow up/bow down". I will draw arrows on my hands indicating which direction to rotate to achieve bow down.
An MG and 29er came out while I was out so I got the opportunity to try chasing them up and downwind. When the boat was working properly it was faster than both, however I was loosing so much ground messing about trying to find the take off angle. I need to learn which sit at prior to take off.

This was my first sailing experience I can remember where I didn't want to get off the water. Other on occasions the wind has died, or I got tired, or cold, or bored. Today the wind was perfect till last light, I was tiring but the boat was so easy to handle that i could just go on and on, working too hard to get cold, bored? not a chance. If I had nav lights I would still be out there.

Bung-holeo!

2009-06-15T08:53:00.003+10:00

Beavis and Butthead spring to mind after yesterday's little problem...

I felt like a rock star when I met Markla at the club. The boat was rigged and I was told to get changed because I had first sail! yay! Conditions looked a bit on the light side but with the stiffer wand linkages it would be a good test day. Also the club were running short course practice races so there were rescue boats and plenty of other dinghy's around (this would later prove to be embarrassing).

Anyway, long story short, the boat was very sluggish and after the second capsize over the transom I realised the bungs had been left out. Markla had also realised this from shore and sent one of the rescue boats out with a spare. Managed to get back into shore, empty the boat (which took forever) then send Markla out for the rest of the arvo. It was a bit of a dud day due to flooding the boat, minimal wind and shifty and gusty wind to boot.

Atleast we both got some air time and didn't break anything, the new parts worked well. Lesson learnt, even wannabe rock stars need to check their bungs.

Zappy Wetsuit

2009-06-10T14:31:00.004+10:00

http://www.boingboing.net/2005/09/23/sharkzapping-wet-sui.html

Could this be used as a training tool? Markla faces backwards on the moth too often and forgets to flip the battens in the light stuff, a quick zap should train him well! Now, where to place the electrodes...

Lazy Evening - New Wacky Design!

2009-06-07T09:27:00.006+10:00

Just some ideas modelled up on a lazy evening at home...aero drag reduction is the name of the game.

Hull is probably a bit too facetted for some ppls tastes, but I like it. Haven't done any drag or take-off assessment of it but I suspect it won't be a front runner.

Iteration 2 will probably run the aft mast support fairing down the sides instead of to a point for structural reasons. Also considering extending the wings fore and aft with a round tube cantilevered from the plank, maybe some netting between them and the hull for a bit more security! It isn't really practical just yet. There'll even be a bonnet for your lunch and keys and a mount for your GPS!

Anyway, off to Markla's for some boat maintenance and maybe a sail this arvo, weather pending. A freak storm just popped up over Brisbane which has put a dampener on mtb plans. The new alloy gantry was put together yesterday, new mast step and base inserts are ready to be installed, alloy cradle is ready for assembly, and I'm sure there'll be some discussion on the new wand linkage ideas. Watch this space.

(Edited title to be exciting!)

193 hulls!

2009-06-01T12:15:00.003+10:00

That's how many we've put to the take-off test recently, all variations of flat bottom, deep V, round, hard chined and soft chined hulls. Early results are in but we're refining and reviewing them atm. Haven't decided if we'll make the results public, but they will be incorporated into our next hull design in some form.

Mothstrosity

2009-05-11T18:31:00.002+10:00

omg wtf!!!11! lmao n00b w00t l4m3rz abft 0noe!

as I and I were on our way back from the Bay to Bay we stopped at Lake Cootharabah to check out the floods - well to see if the lake was still full from the flooding before easter.

The water looked a little higher than normal, but there was still enuf beach to rig on, which means it is still a long walk out to foil depth.

while we were there we did come across this sorry looking moth, complete with outboard bracket.

sadly it makes a better 'thing' than a moth.

bay to bay

2009-05-05T21:24:00.005+10:00

many thanks to Richie and Cassey for the ride on their blazer, bay to bay on the weekend. GPS track to come, but some photos and stats below.

Results:
7th (of 102) Yacht across line in 6:16:10
32th (of 102) Overall CBH
16th (of 39) Overall PBH
1st Blazer

Day 1
Best 1 second average - 10.07Knots
Best 10 second average - 9.16Knots
Best 250 meter average - 8.37Knots
Best mile average - 7.53Knots

Day 2
Best 1 second average - 13.50Knots
Best 10 second average - 11.70Knots
Best 250 meter average - 10.85Knots
Best mile average - 9.11Knots

Overall winner was Tokyo Trash Baby, a i550, shown below. Interesting design and build. A similar kit form to my moth. More details on this boat here and here.

Goin' Yachtin'

2009-04-28T11:20:00.005+10:00

This weekend Markla and I will be tagging along with Woo and Princess Fiona on their blazer 23 trailer sailer, Shrek (it's big and green, not unlike the hulk (but some ppl didn't like that name)), for the Bay to Bay race.

Starting at Tin Can Bay (A) and finishing in Hervey Bay (B), it is a two day race/cruise/piss-up with a stopover behind Fraser Island. Hopefully the mosquitoes don't eat us. Apparently it can also get a little shallow at times, it is after all the Great Sandy Strait. Lots of tacking and or gybing. Wish us luck.

Winglets

2009-04-26T14:45:00.003+10:00

A failed gantry lets me continue my development of my new foilset this weekend. Did a little research and thinking about winglets. Only an overview here, and only the stuff I consider of relevant and of significant effect.

Winglet

What is the effect of adding winglets? The major effect is to reduce downwash, make it harder for the high pressure side to leak around to the low pressure side.

This increases apparent aspect ratio of wing reducing induced drag. But it comes with the penalty of adding parasitic drag without adding any extra lift.

As a consiquence of the above you should always add wing span in preference to winglets.

The induced drag effect is much more significant at high lift coefficients (slow speeds, when your foils are struggling to provide enough lift) so you could see the effect of adding winglets (or extra span) as helping you take off sooner, but it will reduce your top speed.

Wingtip Fence

When are winglets used? Always when wing span is limited
ie by structural considerations
ie by outside influences, such as 15m class in gliders or aerobridges for airliners.

So should winglets be added to your moth?
Only if you need to take off at a slower speed and
1. You are using the same production hydrofoil as everyone else.
2. Your proto foil design is aready solid carbon and at its structural limit.
3. If your moth doesn't look enough like the bat boat yet (but I suggest adding winglets in a more visible spot).

In all other cases, add span, not wingtips, and add more reinforcing if necessary.

Spiroid Wingtip

Name Me

2009-04-21T16:12:00.001+10:00

Only 4 days left to get your vote in for a name. Perverted Moth is out in the lead, but remember that write-ins are being counted so "the boner pirate" and "Leeroy Jenkins" still have a small chance!

FOURTH SAIL THIRD FAIL

2009-04-18T21:30:00.004+10:00

Another sail today. SE 15kts 28deg. Holleywell.

I and I as usual, but today I invited Doug and his thundercat too. Flight more stable but still often ended in a big crash. N4rkla got the top speed 16.66. I got longest ride approx 40 secs. Best photos were of Doug (on his first sail of a moth).

N4rkla ended the day by destroying another of my gantries. A youtube of him below doing the speed of the day.

3

2009-04-14T12:09:00.005+10:00

Third sail on sunday at Runaway Bay. Started at 12knots before falling to 9kts, SSE, 24.5deg.
Testing new jury rigged wand arrangment.

I went out first and could only manage a few launch+crashes before noticing the paddle had come off. Replacing it with 10mm rope did the trick and it was flying for longer before crashing, but still reluctant to take off.

N4arkla the had a go and almost immediately had it up and going. Flying level. I was on the shore and could easily see the spray peeling off the centreboard. I don't know who was more extatic -him flying it or me seeing it works. He clocked 15kts a few times before the wind fell away and the tide rocketting upwind was too frustrating

(I was too excited to take any photos of him, and he hid the camera)

We suspected the wand was turning off the lift too early (before hull cleared the water) and the linkages were not stiff enough to hold the flap down so after dinner we worked this out:

Unfortunately there was less wind on monday, and rain all day, so I will need to wait before I can test this arrangement.

The weather wrote off the rest of the weekend of sailing, but I and I did have a chance for some mothematics.

I and I have had a look over a resistance study by Olav of a systematic variation of Flashearts.
I have developed a steady state foil assessment program the determines liftoff speed and resistance at 30kts while allowing you to vary span, chord and lift distribution between rudder and CB.
N4rkla added SLino to his resistance study and simulated the response of double linkage wand mechanism.

I and I shall post once once we have cleaned it up a bit.

Hull Resistance

2009-04-09T18:29:00.013+10:00

For those of you that don't know, Markla and I work in the marine industry as engineers. Naval architects to be precise. We have at our disposal some pretty neat tools and it is always cool to put them to the test.

For this reason we decided to compare the full scale tow tank resistance data of Bill Beaver and John (better copy and paste this) Zseleczky with results from one of the tools in our kit. It is a program that predicts resistance of ships using a number of methods, one of which is called the Slender Body Method. Basically it uses an analytical method to calculate the resistance of narrow hulls rather than using traditional statistical/regression methods. blah, blah, blah, that's enough background.

Firstly I produced a hull model traced off the Hungry Beaver linesplan in the report (Bill has since sent me a file of his hull which I haven't had a chance to run with yet.). Static drafts for each of the towed displacements were calculated and then run through the program. Neither the dynamic trim nor squat that was present in the tank tests was modelled, for better or worse.

Ok, raw data comparison graphs attached...

So far so good, despite not accounting for trim or squat with the computer prediction, there seems to be some good (but not perfect) correlation. The biggest problems are underprediction of resistance at higher speeds and higher displacements/drafts and the existence of a hollow in the computer prediction at about 4 knots. There isn't any tank data points around there though so it could be a resolution issue.

Well I'm interested in the correlation at the faster speeds (not really that fast) so here's a graph at 8 knots for varying drafts...

This shows a clear discrepancy at the deeper draft for this speed. The difference is nudging 10% of the towed result. Well there's a number of reasons this could be:

Incorrect/lack of calculation of transom drag at greater drafts.
Effects of static trim
Effects of dynamic trim
Effects of dynamic squat/heave

I have no knowledge of transom drag calculation so I'll forget about that for now; static trim may be the cause but apart from the general hydrostatics 0 deg trim I'm not sure what the trims were for each displacement; we have nice dynamic trim/pitch data so this is a possibility but requires many more computer runs to get more resistance data (cbf right now and isn't as straight forward as my lazy arse would like). So this leaves us with dynamic squat (or just plain squat because it only occurs dynamically and really refers to shallow water behaviour of moving ships).

When referring back to the beaver hungry paper, squat increases with increasing displacement/draft (as well as speed, I know, but one thing at a time) so let's interpolate the computer resistance at the squatted drafts obtained in the tank tests.

mmm, that didn't work so well. Maybe not, while the average error seems to have increased (from -1N to +4N), the standard deviation of the errors has decreased (from 3N to 1.5N). Some gains, some losses.

So next thing for me is to get some dinner. On the resistance topic though, I'm happy enough to move forward with assessing hull designs based on the raw computer data. The main reasons for this are that I am happy with the correlation we've seen so far and predicting squat and trim is too hard/impossible with the tools and knowledge I have available so they can't be accounted for in the prediction. I'll probably run the actual hull model through the program to iron out any errors in the results from that area, but I don't expect major changes.

I'd like to thank Bill for his correspondence and congratulate Bill and John on releasing some useful info to the mothing, and sailing, world.

ps - all results are in fresh water, made that mistake too many times with this validation to ever forget again.

Wave picture

SECOND SAIL

2009-04-07T19:27:00.002+10:00

Took (tba) out for another sail on sunday. I survived about twice as long, but was a wreck when I got back into shore. (Holleywell, QLD 17kts SSE, 26.7 deg.)

Boat still wasn't working. Initially it was doing huge lowriding nosedives - standing right up on its ear. One of those I fell out the back. When I surfaced I noticed the boat hadn't capsized and I needed to go swimming after it. Managed to crawl back onto it without it capsizing. I gave the tillerex one turn, and nosedives was no longer an issue. I was rather surprised how effective the twist is.

The foils were consistantly supporting almost all of the required force, but it only took off completely once in 45mins. Then gave spectacular crash. Leg on sidestay = hurt. Will wear full wettie until i can sail it properly.

N4krkla then had a go. He was too scared of dropping the rig to pull on enuf vang and wasn't cracking off onto bogan reaches. He prolly would have gotten to it, but the tiller universal popped off and we swam it back to shore.

When we were derigging we noticed that my fibreglass rod that the wand pivots on has failed so wand wasn't actuating the foil. Prolly explains why it wasn't inclined to fly.

Interestingly N4rkla commented that the boat was a lot more docile than he was expecting. I am inclined to agree. Probably a combination of good bouancy in the wings, flat sail, low freeboard, and to a lesser extent, dampening in roll provided by the chines.

On a seperate topic, I and I have run the hungry beaver thru a Slender Body resistance package and the correlation to Bill and John's research is surreal. We are formalizing the calcs at the moment and will post the results later this week.