Ride Your Bike

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.)

Wing Design Concepts

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

1. full composite - likely to be too heavy and expensive
   
2. 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
   
3. sock over frames - with spinnaker clothe, light, cheap, not likely to be water tight and durability concerns
   
4. styrofoam modules - cheap, heavy, don't capsize on a petrol slick, UV issues, water absorption issues.
5. composite and heat shrink modules - demountable for better transport, a bit heavy, easy(ish) to build
   
6. 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.
7. 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...