Darryl, in the F18's the width limit is the american max. towing which is wider than the Australian maximum. This means that if you want an F18 in Australia you need to have a tilt trailer or suffer in higher wind strengths. Aparently Nacra Aus. refuses to sell wider beams unless you can prove you have a tilt trailer. Easier just to regulate the F14 max. width to Oz std.
A minimum weight should also be set to keep the costs to at least a sensible level unless you want your new boat to be obsolete in a year or two when the new ultra light weight moulding compounds requiring a megga $$$ process, becomes available. I think 70kg (155lb) is probably equitable at this stage with an option to look at it again in a year or two.
Bern
Bern