Rick, It looks like I would've had very little chance of winning the competition for a sail on Bucketlist if your polar SW is accurate... =)
Did you write it yourself?
My guess was 18 knots boatspeed upwind (12 knots VMG), and 29 knots boatspeed on the best point of sail. I based it on a simple VPP in Excel, but it didn't take some factors into account, like pitching. It did take the aero drag of the hulls into account though, and had pretty good estimations of the hull resistance (from Michlet) and sail lift/drag (from XFLR5). I neglected the aero drag of the beams/tramp though, which might be the most significant aero drag on the boat.
If Rob keeps the contest going for the new foiling version, I might have the best guesses though, because I think my guesses where the most optimistic of all submitted. =)
On Fri, Jun 8, 2018 at 11:19 AM, Rick Willoughby rickwill@bigpond.net.au [harryproa] <harryproa@yahoogroups.com.au> wrote:
If you like looking at curves you may appreciate the polars I did for Bucket List. I was hoping to have the opportunity to verify them but that cannot happen now.
https://1drv.ms/b/s!Aq1iAj8Yo7jNgwTupZm4ls6IoAOs I cannot remember the details now but I think it sailed fastest with three on board to load the ww hull. But 57sq.m on an 18m mast is a powerful rig for a light boat. For the linked polar I set the minimum sail area to 20sq.m. It would have been able to carry the full 57sq.m in 6kts on all points but above that it reduces when on the wind.One thing I did determine, it would be unlikely to get over 25kts without uplifting foils because it would nose dive.On 8 Jun 2018, at 6:13 pm, Björn bjornmail@gmail.com [harryproa] <harryproa@yahoogroups.com.au> wrote:I don't think its good design to put more than 50% weight in the WW hull, because then that hull needs to be almost as long as the LW. More beam and a lighter WW hull (Rob says 40%) would be better. But I think this isn't really the point here, to look at the static numbers. It's very easy to change same parameters, which will shift shift either curve up or down. What I thought was interesting was the shape of the curves. It's just like Rick says, the proa has less heeling moment at higher angles of heel, and the cat the opposite.
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Posted by: =?UTF-8?B?QmrDtnJu?= <bjornmail@gmail.com>
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