Again Wouter you are talking about your design not mine,
I'm not, my mathematical models don't use specific design limits of my F12 design. They assume "perfect" sails meaning that the results of these models act as upper boundery to speed potentials.
As such you windsurfer rigs are also limited to this upper speed boundery.
They may react differenty to gust onslaughts however. But I've seen enough windsurfers being launched by their rigs to know that there is a limit to gust response.
The gust response of these sails is very good I would not expect to see the situation you describe.
You are not thinking through your counterarguments. On a dead downwind run any gust response based on mast flexing or squaretop sail design is useless. You will only be bending in the same direction as the gust is blowing without the sail area being weathervaned out. As such there is no reduction in sail force. When the apparent wind is coming from the front then pitching is not a problem anyway because the craft will capsize before it will pitch. In effect the improved gust response of a windsurfer rig will only help you on the reaches.
This is a similar rig to that used on the international moth that won the world championship a few years back so perfromance is not as bad as you are trying so hard to make out.
Sorry, but this is one of those bullshits argument.
It sounds nice and convincing but it is actually only succesful in making people believe errornous claims/conclusions.
The NON-FOILING moths are speed wise somewhere between the Hobie 14 and the Hobie wave. It is the FOILING moths that are achieving the impressive speeds. And this not because of the sail design but because of the much lower drag while foiling. The difference between a foiling and non-foiling moth is no less then 25 % that is a BIG performance gap. (Source Empirical Australian VYC yardstick handicaps)
F12 will not be foiling and as such we should not look at the foiling moths to get a feel for the F12 performance. Additionally the moths use 8 sq. mtr. sails on a longer luff, their masts are 6250 mm tall ans as such 35 % taller then 4600 mm the windsurfer rig. Your sail has an aspect ratio of 3 (at max) while the moths use sails with an aspect ratio of 4 and higher. Because of this your sail will provide 25 % less drive then the moth rig.
Additionally the F12 will be between 55-65 kg ready to sail while the moths are 35 kg ready to sail. This all adds up.
The NON-foiling moth is rated 10 % slower then the Hobie 14 (VYC 94.5 ;Texel 135) and as such is rated the same as the Hobie wave (Texel 146). With your smaller sailarea your craft will be slower still. Texel provides a crude estimate of 149 with your 7 sq. mtr. windsurfer rig.
Here it should be noted that punching in the Moth specs in the Texel rating system produces a rating of 133 which is very close to the Hobie 14. Note how the NON-FOILING moth is rated 9 % slower with the FOILING moth being rated 12 % faster.
Despite its crudeness it never fails to surprise me how close the Texel rating system always seems to predict actual performance of a given craft.
Wouter
