Originally Posted by bill@custardpie
OK maybe this is a simplistic question but:
Beat to windward in a Force 3-4, flatish water, standard production 21st century cruiser/racer fractionally rigged
If you have a choice between an overlapping 120% genoa sheeted around the shroud or a smaller say 100% blade jib sheeted to barber haulers inside the shroud.
Lets assume the blade will get you close to the speed the polar diagram predicts. Will you get anything more from the 120% genoa ?
Which do you go for ?
On a frac rig, most probably the blade will result in a faster sail plan output .... and enhanced pointing ability.
Reason: a blade 'can' be sheated INSIDE of the shrouds and without fouling on the spreaders .... and can be more easily adjusted to the defining 'slot open' distance. In F3-4 that 'attack angle' (tack to clew) is probably going to be somewhere on that 10° line offset from the tack.
If the 120 fouls with the spreader .... "no soup for you !"
Of course, you yourself have to do 'trials' with reference to correct 'slot open distance' vs. VMG once you get close to your final decision. When youre in this final stage of optimization, forget any so-called backwinding to the main ... simply finalize your plan based on speedo output and VMG.