When I put the spin on my Nacra 6.0, I just installed an eye bolt (3/8" diameter?) about 1.5" back from the bow, about 1" down from the deck. The glass is really thick here, and will handle the load fine. I put a rubber gasketed washer on each side of the hull where the bolt went through, and made sure to use 5200 around the hole to prevent leaks. I never had any trouble. I would recommend New England Ropes- Endura 12 line in 1/8" for the spin bridles. I have used it, and it is great. I can splice it if you'd like as well (no knots!), or you can just use a bowline. There is no need to use a purchase on the line, as a single one will be more than ample for the load. PM me if you want more info.