Does any one know what the current trend is in the development and high performance classes on issues like design draft of the sails, position of maximum fullness, distribution of draft vertically in the sails, relative use of broad seaming versus luff shaping for developing the fullness and how this has changed in recent years??

I'm sure somebody knows and I'm equally sure the likes of Hyde etc will not be that willing to discuss it but it would be nice to know...

Cheers!

I don't know but if I speculate perhaps it'll draw a reply from an expert.   I'd say that there is less luff round and more broadseam in modern sails because modern materials don't stretch as much and so can't accomodate the luff round.

I'm really impressed with modern sails.  I used to sail a RS400 and the mainsail was so adjustable, its a powerful sail which with plenty of Cunningham and some mast bend can be made very flat at the top and suitable for for very strong winds.  Similarly with my Laser4000.  Both boats have fully battened mains, with loads of roach and a means of letting the mast bend - ram on the 400 and lowers on the 4000.  The 4000 in particular is very happy at 30knots, and the advantage of the flat top is that flogging is not required and so there is little drag and the boat therefore really motors to windward.  In fact going to windward in a 4000 gives you an apparent wind of getting on for 40knots and that feels very windy, but earily downwind it all goes quiet (I am speaking relatively).  Incidentally these fully battened sails last a long time which is just as well as they are not cheap.

Maybe the reason your initial question didn't generate any replies is that there are no real overriding trends which cover the whole spectrum of sailmaking. It's impossible to say that sails are getting flatter, or other such generalisations.

In dinghy sails, each class has its own very specific requirements, with fully battened sails on fast planing boats generally having more luff curve and less seam shape than soft sails on old designs. On top of that, many classes have their own peculiarities. Overpowered classes, typically sitting out boats such as the Finn, tend to have relatively powerful bottom sections, and flatter top halves, wheras underpowered classes such as the 420 will have a more even distribution of shape, but that's a big generalisation.

Also, sailmakers are notorious for not talking to each other very much, and often tend to specialise on their own classes or areas of expertise, so may not have all the information.