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another non-use of helium This would spoil all the fun. We had all these uninformed speculations that would be instantly deflated, no pun untended, if they just used helium to squeak past the waterline measurement. It seems like measurement rules would require that the helium be retained...

Nitrogen It's interesting to listen to a bunch of sailors talking about race tires. If you take humid air and compress it the partial pressure of the water vapor will go up. The temperature will go up also, but as that air cools back to ambient, some of the moisture can condense. If you...

Itd You guys are all suffering from ITD. Sailors love special vocabulary, so I invented this TLA (Three Letter Acronym) just for the occasion. It stands for Internet Thread Disorder. This term should applied when (almost) none of the postings relate to the original thread subject and every...

You're right of course and I have that book. I think I got a little ahead of myself, because I dove into JavaFoil and started playing with two element wings, before I compared the output to experimental results for a simple shape. I now more or less know how to use JavaFoil, but I'm not...

I tried 51, 101, 201, 401 and 801 points. The polar seemed reasonably stable between 401 and 801, but it does run slower at 801. At Re = 1e6 it did change some with different numbers of points, but much less across the full range.

Reynolds number and foil points Rick, Thanks for the reply and the link. I think the link covers JavaFoil vs Xfoil pretty well and leaves me with a quandary. Since stall is pretty important, JavaFoil doesn't look too good for wing design. For instance, it's hard to keep thick foils from...

I've thought a little more about this. Some (most?) of the composite materials are better in tension than compression. You probably also need some additional skin stiffness on the lower parts of a float to resist wave action. These are two reasons that the bottom of the hull is probably...

No shortage of insults on this forum. Is a reasonable answer ever expected?

It didn't seem to get much notice, but I read a statement that the M2 was designed to carry more load on the the rear foil. I suspect I could find it and it might have been on the M2 website.

Yes, it seems to me too that Bill and Doug are agreeing. But, while English is my first language, I won't claim any expertise there and I'm happy to be corrected. I noticed that the forward foil on Mirabaud was significantly ahead of the mast. The main foil on a Moth is in a more "normal"...

$'s per second There are one or two areas where AC rules, in the past, limited technology to control costs. Hard as that is to believe. With a lead sled you can get densities significantly higher than lead. Tungsten is a lot more expensive, although it is used in darts. You know, the kind...

JavaFoil doesn't match I've been a little concerned that I was getting separation at what seemed like relatively low lift coefficients when I've been playing in JavaFoil, or at least less than I hoped for. Then here in an earlier post, the plot from Tom Speer/Xfoil for a NACA 0012 was better...

Actually, I think we agree Since we are talking about "America's Cup: what's next?", does anyone hope that there are engines powering the rig next time? I didn't think so. I'm guessing that Alinghi made that rule in part to disrupt the BOR campaign. Or, maybe they knew that BOR would have...

tactics-technology-spectacle As a sailor I like the tactics and particularly the start. As an engineer I like the technology, but if you want viewers, you need spectacle. Spectacle may not be exactly the word I'm looking for, but it will have to do and that's what brings in the viewers. I...

I added a couple more lines to the graph I stole from Tom Speer to compare the effect of sealing the bottom to adding aspect ratio. If you seal the bottom - perfectly, the optimum plan form changes and that lowers the heeling moment. You can then increase the aspect ratio by about 30% and the...

Practicality and common sense probably doesn't include skiffs, A-cats, IC's and a bunch of other cool boats too. Certainly not a Volvo 70, or G3. A while ago I ran across a S. Hemisphere discussion of handicaps. One boat that ranked higher than I would have expected, especially considering...

Wait, that's too easy! On many boats the boom position is hard to lower, but some skiff boats have that extension from the below the boom to the mast. On a cruising boat you might benefit from a wish-boom type boom and a sail that brushes the cabin roof for part of the way back. Still even in...

The top is where people first think of doing something, but in addition to adding weight, it also moves the center of effort up which is not so good. Increased aspect ratio should be taken as far as available righting moment allows. The question is, what do you do next? There is more...

The bottom of the sail This thread is almost 2 years old, but I couldn't find any newer ones that were as close to what I've been thinking about. I've drawn some lines and guessed some numbers from Tom Speer's post 15 and you can see the result attached below. My red lines compare two designs...

You would probably be best off looking here: http://www.boatdesign.net/forums/design-software/savitsky-power-prediction-2187.html