OK it's time to bring this section up to date. We want to make it a mine of information on Moth and foil design, technology and building. If you are involved in any way and want to publish ideas or experiments, please send them in and I'll make you a page. Students' papers are especially welcome and can be posted in pdf format.

8-9-08
Setting up the current foiler designs is something of a dark art. yet a badly set up foiler is like cycling through Rio with two flat tyres wearing a mankini (sorry if that image haunts you). In today's article the top two sailors in the two leading designs, give us their post Worlds set-up tips...

16-3-08 Foil ventillation
Adam May writes - The front of the foil is the key with the ventilation problem.
To quote Marchaj “The rudder ventilates at certain angles and flow velocities due to the low suction pressure over one of the surfaces (mainly the windward surface). When this pressure is below atmospheric pressure, air can flow down the surface of the foil, causing a dramatic loss of hydrodynamic lift. Ventilation can be control through the use of fences that act as physical barriers to the passage of air.”
The link is a screen grab from a simple cfd program showing the pressure distribution around a typical 0012 section foil at 4 degrees angle of attack. You can see the large suction peak near the nose on the upper surface. On the right, is a photo of a nicely ventilated rudder, but control is retained enough that I could get a camera out and take a photo of it!
I use one fence about 120mm up from the rudder foil wrapping around the front. It doesn’t prevent ventilation but when it happens it enables you to keep control. Fence design is quite well documented when you start looking into it.
Water properties, fwd rake, section shape all influence the behaviour, and there are a number of people pondering ways to prevent it on our rudders! After a weekend of not being able to go downwind without a plume of water behind me I’d certainly like to get to the bottom of it. (Or just wait until it gets warmer!)

21-2-08 Rigging choices
Mike Lennon shared his experience of alternatives to wire rigging on the Yahoo group. Here's what he posted...
I have used the braided PBO by Gottifredi Maffioli which you splice your self, and the stuff you buy pre made from Easy rigging. The Easy rigging is the lower stretch and lower windage route but not as durable and more expensive.
I broke the plastic cover on two sets on my 14 -- one from spin sheet wear and one from spreader wear. Both breakage's are probably 14 specific and not a problem on the moth. The Gottifredi has been on my I14 for 2 seasons -- Same set no problems. It has very robust spectra cover. The easy rigging has a plastic cover which will only take limited abrasion and load -- ie if a spreader grips the cover before the stay is tight the cover will snap exposing the fiber which degrades quickly in day light. My latest set from Easy now have Dacron cover. Thicker but durable.
I used 4mm Braided vectran on my forestay ( i14) until i started with the pbo and it held rig tension ok, but it takes more travel in the rig purchase systems to get to load. Once there it worked just fine holding the same static load as wire. I tried 3mm vecrtan on the uppers shrouds but could never get them to load as the system didn't have enough travel.
I am using 2.5mm Gottifredi PBO on the Moth right now but will switch to the 2mm easy rigging at some point
I never tried Dyneema due to the creep ( elongation without recovery). I believe Marlow have developed some creepless dynemma recently but i have not used it.
http://www.gottifredimaffioli.com/en/products/yachting/vz.php