Hi Wouter,
been away from my pc for a few weeks and bumped into this thread, to answer your question :
"Currently I'm thinking about a max sail area limit (single sail) of max 6.0 sq. mtr. on mas 5.25 mtr masts. As for this area and mastsize I know the landyacht rigs will hold (no further design work involved here). But will that be a good max size for the people looking for cheap second hand surf sails."
Typically a 6.0sq.m sail will be rigged on a 430 mast with a 15cm extension, giving mast length of approx. 445cm. Race sails will be shorter in the luff and longer boom length while wave sails will be set on short booms with slightly longer masts. My Neil Pryde Race sails are 5.9sqm, 445cm mast incl. extension, 186cm boom. My 6.6sqm is on a 468cm mast, 197-200cm boom. Both have camber-inducers which I think would be unsuitable for use on a catamaran, when gybing or tacking you really have to bang the sail over to get the battens to rotate - on a cat in winds less than 15knots this might be almost impossible to do unless you stood up and man-handled the boom.
The problem with allowing windsurf sails in is that while some folks will buy cheap stuff on e-bay, others will buy full-on race equipment that will easily cost much more than the rest of the boat.
I would suggest that if you allowed windsurfer sails to be used you set up quite strict criteria, I would disallow full race or speed sails, no camber inducers. Stipulate the max. carbon content of the mast at around 40% - a 100% carbon mast can cost 4 times what a 40% carbon mast costs. Allow only aluminium booms - again full carbon booms are really expensive compared to alu. booms. If I were drawing up class rules that allow windsurf sails to be used i would even consider making up a list of permitted sails, or stipulate that only non-cambered free-ride or wave sails can be used.
You could also limit boom length to 190cm, mast length to 450cm and sail size to 6,0sq.m, that will stop vastly different shape sails from being used (to an extent). The problem is that windsurf-sails are so different in shape, outline, draft, twist and aspect ratio depending on their intended use, which is why I`d make up a list of permitted sails, like the Naish Vantage or Sprint, and similar sails from the other manufacturers. Have a look here :
http://www.naishsails.com/products/sails/index.htmlThis gives a good idea of how different the sails can be - the Naish Boxer would fit all the criteria I have mentioned but is vastly different in shape to the Vantage or Sprint.
Also need to consider - if you stipulate a max. sail size, nothing to stop folks from having 2 or 3 sails that fit in the criteria, so if it`s blowin` hard they could rig a 4.7sqm or 4,0sqm sail and still race. Good for versatility of the class, bad for keeping costs low. Just things to consider.
Oh yes, boom height is between shoulder to chin height. Good luck with measuring that one.
Hope this helps..
Cheers
Steve
