Texel says
<br>Maximum spinnaker area
<br>Boats up to 16 ft. < 4.87 m.: 17 m 2
<br>from 16 up to 19 ft. > 4.87 m. <= 5.80 m.: 21 m 2
<br>from 19 up to 22 ft. > 5.80 m. <= 6.71 m.: 25 m 2
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<br>So I don't understand where your 18 sq. mtr. comes from.
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<br>The reasons on which the group decided on a start with 17 sq.mtr. a few weeks ago are however :
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<br>-1- The 21 sq.mtr was found to handle worse and have disporportionally higher sheet loads (found by 4 of the groupmembers , 2 USA and 1 EU and 1 Aus).
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<br>-2- Furthermore Taipan america has decided on offering 17 sq.mtr. if Kirt's info is correct. Taipan Aus (Goodall) is in doubt wether to go for 17 sq. or 21 sq.mtr. But it will be one of these. Most groupmembers have 17 sq. mtrs. already ( at least 4 of them) and one member has gone even smaller as a result of his experience with bigger kites on Taipan 5.7.
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<br>-3- 17 sq.mtr. comes closer to the 83 % rule than 21 sq.mtr or even 18 sq.mtr. 83 % * 21 = 17,43 sq. mtr.
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<br>-4- BIM 16 has a 12 sq. mtr. kite It might well go up to 17 sq. mtr, and a little more luff length but. 21 sq. mtr. will be to much.
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<br>-5- It is a Formula 16 foot class (even though it is a little longer than actuall 16 foot) Texel 16 foot max is 17 sq.mtr. we wanted to stay with the spirit of the rule.
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<br>-6- The F16 HP is setup such that the solo class uses the same materials as the 2-up configuration, this includes the genaker. This to provide the class with an easy switch from 1-up to 2-up without extra investment. Going to 21 sq.mtr will severly hamper this. The switch is together with the F18 equality are the two "selling" arguments of the F16 HP, without it the class will be hard pressed to get out of the experiment phase.
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<br>-7- 17 sq. mtr. is what the soloboats I-17 and FX-one use, so it was considered to a good (max) size for the F16HP 1-up. Especially with the lower sheetloads.
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<br>-8- And deregulating size will lead to confusion during possible future F16 HP get togethers.
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<br>-9- Well known sailmaker in NL was reluctant to go bigger than 19 sq. mtr. on my P18 for he said :"the is not enough room to optimally fit 21 sq. mtr. in the dimensions of the boat". So taking into account that the pole tip to sideshrouds on the F16HP is about 91 % of the P18 (F18) makes any gen over 91 % * 21 = 19,13 sq. mtr. less effecient than the F18 gen, when aspect ratio is assumpted to be important (Bethwaite)
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<br>-10- Grandfather boats whose masts are 8,5 on average to 9 mtr. of F18 => 94,4 % => 94,4 % * 19,13 sq. mtr. = 18 sq. mtr to have same efficiency (aspect ratio). But then again this is not a real necessity but by a large part a choice (equal to F18). F16HP will therefor have a higher aspect ratio even when the 83 % rule is observed so it already has a small advantage over the F18.
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<br>-11- F18 weight (140kg) to gen. power ratio with 21 sq. mtr. >= 15,23
<br>F18 ,, (115 kg) ,, ,, ,, ,, 19 sq. mtr. >= 15,52
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<br>-12- F16 HP weight (140kg) to power ratio with 17 sq. mtr. >= 14,11 (IS less weight per gen. sailarea, better accelleration)
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<br>-13- Therefor the F16 HP already had a 8,4 % higher acceleration when coming out of a gibe. That is with equally efficient genakers producing proportionally equal thrust. Going bigger will offset this alot.
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<br>-14- No other solo or two up catamaran design has gone higher than 17 sq.mtr. as far as we know (Stealth ?)
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<br>These were the reasons to limit the gen size to 17 sq. mtr.
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<br>There is a strong tendency to vote in a clause that allows the F16 HP rule to be opened up more later, after the class has established itself but for the beginning it was voted to go for more control so that we have a good change of actually starting the class. And also to make it is easy and relative inexpensive for people to swithed to F16 HP.
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<br>With these points in mind I would like to stress that really convincing arguments are needed to reverse the 17 sq. mtr, decision now.
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<br>Wouter
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<br>This
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