De rule itself will remain unaltered as she works and is used by ISAF and Texel measureres as well as in teh F18 and iF20 class rules.



However, by measuring our own spinnakers we found that the new high aspect spinnakers of today very closely approximate the formula



SMG = 75 % * SF instead of SMG > 75 % * SF



In other words they are compliant with the rule SMG > 75 % * SF by being just an extremely small fraction wider then SMG = 75 % * SF.



Thanks to a friend who did do the math on the subject de calculation rule for the size of spinnaker could be made much less complex.



Under the assumption that SMG = 75 % * SF the formula for the size given by



area = SF * (SL1+SL2) / 4 + (SMG-SF/2) * (SL1+SL2) / 3



simplifies to :



area = 1/3 * SF * (SL1 + SL2)



Where



* SF is the length of the foot measured around the edge of the sail between the lowest points of the luff and the leech ;



* SL1 is the length of the luff of the sail, from the highest point of the sail, to the lowest point of the sail on the luff ;



* SL2 is the length of the leech of the sail measured along the edge of the sail, from the highest point of the sail, to the lowest point of the sail on the leech.



And SMG is is the width at mid-height, which shall be taken between the mid point of the luff and the mid point of the leech





Clearly the second rule is much easier to use during boat checks at regatta's and most people will understand the second formula and not the first.



Remember that both rules give the same results ! The rule itself hasn't been changed.



The proposal is that the new wording is something analogue to.



The spinnaker must satisfy the condition : SMG > 75% * SF



Way of calculating the area:



When the spinnaker satisfies the condition 75 % * SF < SMG =< 77 % * SF than the area is calculated using the formula :



area = 1/3 * SF * (SL1 + SL2)



if the spinnaker satisfies the condition SMG > 77% * SF than the original ISAF formula is used :



area = SF * (SL1+SL2) / 4 + (SMG-SF/2) * (SL1+SL2) / 3



Where :



Bla, bla, bla



**



Or maybe somebody has a better, even simpler, wording that leaves the meaning in tact but makes the whole rule easier to understand.



One party suggested that the class could rule that all the spis used satisfy the condtion 75 % * SF < SMG < 77% * SF and just have the derived formula in our rules set.



This condition will still be fully compliant with the Texel and ISAF rules and all new spis are practically of the condition SMG = 75% * SF anyway. So no-one would get hurt.



Any ideas with respect to this topic ?