Ramblings on Dinghy Development

Originally posted by Peaky The 59er is very spikey, the only direction you want to go is 137 degrees as it is fastest and best VMG. So not ideal for club courses.

You see that's where I differ from majority feeling. I don't have any problem with a spikey curve for racing my boat. If the leg is deeper than 137 degrees then I gybe down, no problem, and if its less I sail a combination of the optimum three sail and optimum two sail courses, and if I get it right I'll go very fast indeed. Yes, its a considerable tactical challenge to judge all those angles and hoist and drop points right, but you know, if we wanted it easy we'd race RIBs. The problem comes for the race officer, because if he happens to set a 137 degree course the 59ers win by a mile on handicap.
The 200 doesn't actually offer any more tactical options, because you still have to hit the optimum angles for optimum speed. The difference is there's much less of a penalty for getting it wrong.

Originally posted by JimC The problem comes for the race officer, because if he happens to set a 137 degree course the 59ers win by a mile on handicap. The 200 doesn't actually offer any more tactical options, because you still have to hit the optimum angles for optimum speed. The difference is there's much less of a penalty for getting it wrong.

Very true. The 59er would clean up on its perfect course, but struggle to be in the beer on other days. The 200 is likely to always be there or thereabouts, but perhaps always the bridesmaid. It keeps the fleet together, and therefore *feels* like closer, tactical, racing if the speed penalty for sailing in the wrong direction is less severe.

Which kind of proves the point I was trying to make.

I got the 59er drag curve from Bethwaite and made some simple assumptions on the lift and drag coefficients of the sails. Then it simply a matter of balancing heel and righting moment. Other boat drags I just tweaked the 59/tasar ones based on whether the boat is longer, lighter etc. Very crude, but useful in a geeky way.

I'll send you the spreadsheet tonight Dan - it's a bit manual but could be automated with a macro.

Originally posted by Daniel Holman Originally posted by Peaky Interesting plots Jim. I produced these rough polars for the 59er, 100, 200 and Halo some time back, based on 10kts true wind. The 59er is very spikey, the only direction you want to go is 137 degrees as it is fastest and best VMG. So not ideal for club courses. The 200 is much smoother, with a wide range of angles offering similar VMG downwind, which is more forgiving, open to a range of tactics and suitable to a variety of courses. How did you derive these polars mate?

Very interesting. thats how i'd see the 200 vs 100.
Could you do some more classes?

Alex