So after some reasonably positive feedback, here are a couple of concepts. Please be gentle...
Two (of the many) possibilities are shown.
The dimensions required are:
AA - socket chord (should be maybe 10mm bigger than a standard blade chord)
BB - socket thickness (should be maybe 5mm bigger than a standard blade thickness)
CC - minimum height of pin centre above deck (for easy removal on concave decks, convex decks won't be limiting factor)
The only reason you would want a "standard" is to make quick to exchange foils between proto boats. Seeing your sketch makes me think that this requires people to easily adapt the foils to different freeboards. This could be achieved by a series of holes, or a removable top plug. But series of holes is messy, and would leave a hunk of foil above the deck which would by noying. Where you put the push rod cam is also open to question.
ReplyDeleteAs a home builder I think you should just see what the most common foil is on the market, and ensure your boat fits that foil.
As you have done on SLINO I think rectangular case with cassette, or bog on CB is still the bestest for proto boats. Leave the trapazoid for the production boats.
There is just too much futzing around with angle of attack to make this worthwhile, unless you make it adjustable somehow, in which case a leading/trailing taper doesn't really make sense. All the BR sailors monkey with AOA, down at the foot, ditto the Mach2, and probably Prowler though haven't seen the latest examples.
ReplyDeleteMaking the trunk structural also sounds like more material than necessary; current trunks only need be thick enough to keep the water out, with bulkheads taking all the load, and some G10 plate molded in for the pin. With a taper the whole thing needs to be beefier.
It would be cool if everyone could agree on something but the main players will not want to make it easy for people to use other manufacturers' foils on their boats, and the homebuilders want the flexibility to try anything, so the taper is left without a constituency, or so it would seem.
PS - What does SLINO stand for?
That is just one of the valid reasons? Anyone who wants to change a foil or hull for whatever purpose (breakage, experimentation, buying the latest and greatest) will benefit...if a standard is adopted by builders. Prototype or production.
ReplyDeletefreeboard to deck CL for proto boats can be tuned to foil depth like it currently would be, eg. SLINO.
It's easier to change the pushrod and fittings than to cut the boat open. Noone likes carbon dust.
The trapezoid is not significantly harder to build than the rectangle, if at all. It would be lighter and easier to fit the foil when on water (self aligning). I see no reason to lose those benefits just to make it rectangular.
But it is upto the class members to start adopting a standard that suits them and as long as it works it doesn't matter what it is. There are plenty of scenarios in which two competing standards have been developed and only one has survived, VHS vs Beta, blu-ray vs HD DVD. Admittedly it is probably best if a foil builder adopts a standard first then everyone else can follow.
Aren't AOA changes done with packers between strut and foil atm? Why doesn't the taper make sense, it is harder to modify a foil to change AOA at the case than it is to change a rectangle or trapezoid.
ReplyDeleteThe case itself can be whatever it needs to be to fit the strut head as drawn above. Rake adjustment is a no-brainer in this case.
It doesn't need to be beefier, it can be built exactly the same way.
I think builders are doing themselves a disservice by being different in this respect. Owners would be much more likely to buy a new foil from the current "fast" builder if they didn't have to grind carbon to make it fit.
I'm not definitively pro trapezoid and it is beyond the point of the discussion. It is really about whether or not a standard should be adopted. What I drew up in 15mins above is just one possible solution. The rectangle is just a special case of the trapezoid.
I see this as a bit like the evolution of, say, the boltrope slot, or the gooseneck / boom interface design in proctor "D" spars of days past.
ReplyDeleteBasically it happens because it is a good idea, and there was significant specialization in spars (and sail makers)such that the market "met" at a design that just works.
For a defacto standard to evolve there needs to be a proliferation of foil builders (all you CNC hobbyists are listening, right?) and probably a transition into a small quiver of foils for different conditions being the norm for the racer. The hull builders would probably love to subcontract out the foil (and wand system) to a third party.
But as with the north sails offering and the "perhaps too much choice" perspective bandied about lately, I think it will need to occur in vastly better economic times...when price resistance, and "buyers remorse" is a weaker force than the current climate offers.
I like this idea. But it's very 'un-Moth'.
ReplyDeleteAnyway we have four builders (with boats) on the exhibition stand at the London Dinghy show in two weeks time - so I'm gonna print your blog and give it to them.
Maybe they'll shake hands on it - haha
haha, it is a problem.
ReplyDeleteGreat! Definitely give it a go, no harm in putting it out there.
It's too late, we/they all have tooling already.
ReplyDeleteWhen you sailing anyway? Has it been in yet?
I've had the hounding for months, your turn :)
Tooling deteriorates and needs to be replaced. Modifications can be done if there is enough demand. I don't actually envisage that the head would be built into the strut mould. Rather a separate 2-part mould that "grips" the existing head. Hull or cb case moulds are another matter.
ReplyDeleteIt won't happen overnight, but there are positives in the long run.
M4rkla was getting the bushings made yesterday. Deck lacing, vang and smaller hose-clamps for wing attachment are required. I'm not willing to put a date on the launch yet.
Keep hounding, there's only so much hounding M4rkla will take from me before the wave of the hand to dismiss me.
You a pro boat builder?
ReplyDeleteI and I am currently only able to work on the boat 5 hours a week. Last weekend I accidentilly started watching Neon Genesis Evangillion episode (Anime(Japanese(teenage angist)animation)) and didn't get to the boat.
Remaining jobs are:
This weekend’s jobs are:
- Wing lacing drill and fill
- Bung, drill fill and fit
- Centreboard filler
- Fabricate wand
- Assemble boom
- Cut aluminium for cradle to size and angle
I can cut at least two things off your list for you!
ReplyDeleteYou don't need a bung unless you think it will leak. Someone I know says that it is admitting defeat.
You don't need a cradle to go sailing. You can rig the boat on cushions and store it on an office chair.
Plus you could sail commando and then you don’t need to do the lacing holes either.
Al's right. Commando it up M4rkla! If it leaks, drill a hole. Assassin has proven that an office chair will suffice for launching. I knew there was a reason it had a flat bottom, to sit level on roof racks.
ReplyDeleteBut no launching this Saturday, mountain bikes and Gero need some love.
I'll bring a splicing tool and hiking bench on Sunday too. Need anything else?
ReplyDeleteVanessa's is going to love the hiking bench, last time I saw it it still looked like something that was left beside the road outside Nick's office. .
ReplyDeleteLove the line about admitting defeat, but I have alredy drilled relief holes. That carbon black hot in the sun.
I am a little worried about the airex, the panels get noticably softer in the sun, and there is no published heat deformation temperature, just a graph of reduction in properties with temperature. Luckilly there is no horizontal carbon finished parts.
The sides will probably be horizontal for the majority of the first couple of sails. hehe. Atleast the hull will be in the water though.
ReplyDelete