Hi Dave,
I think your on the right track. The capsize moment is simply the weight
times 1/2 the "beam", but dynamic loads (wind gusts, sharp turns, bumps,
etc.) are more difficult to quantify. On my last wing sail project I
doubled the capsize moment to account for dynamic effects. Crude, but you
have to start somewhere. The next step is to use the beam equation, Stress
= MC/I, to calculate the required mast size and thickness ( I ), for an
assumed stress level. If your building the wing out of composite materials
its a good idea to build some samples, test them to failure, calculate the
failure stress, and use a percentage of this stress ( 50% ) in the beam
equation to calculate the minimum I (moment of inertia) required. SKEN'S
ELEMENTS OF YACHT DESIGN has some examples of the basic process. You can
get more details on my wing sail projects at:
http://www.johnsboatstuff.com/Articles/rigid2.htm .
Good Luck,
John


"Dave Schneider" wrote in message
...
Does anyone have advise on how to calculate mast/sail loads? This is
actually for a solid wing ice boat, but I think if I can understand
traditional mast/sail loads, it should translate to my application. I
don't think aircraft design is applicable here, especially G-forces. The
key point for boats vs. airplanes is that you can only apply so much
force,
and then the boat will start to capsize and spill the air. For sake of
example here are some parameters:
weight: 500lbs
sail area: 50 square feet
center of effort on sail (wing): 6 ft high
plank: 14 ft (7ft from hull to runner)
estimated speed (if it matters): 80mph

I don't know how to figure this out with an equation, but by simply
examining movement distances of the CE and hull, it appears that the sail
has a mechanical advantage so the load on the sail would never reach 500
lbs. I also have to account for loads encountered in a gust.

Am I on the right track here? Can anyone recommend some reading on this
matter?

Thanks for any assistance,
Dave