Carl,
Nope, must be a different company from Great Lakes Sports. Nothing to do with Iowa. Great Lakes Sports Mfg. Co. was in Ohio, Greater Cleveland Area. No welding involved. No visible bolts, rivets, seams, or anything. The Sizzlers were actually very pretty boats, made of stretch-formed aluminum and filled with foam. Beautiful paint jobs on them. Very sleek and racy-looking. The deep-V shape of the symmetrical hulls was what inspired Hans Geissler to design the G-Cat the way he did. Some new people in Cleveland recently bought all the left-over hulls and all the machining equipment and were planning to start building them again. I think I kind of discouraged them. You know me -- I think there are already too many designs on the market.
Paul Swenson, the engineer who designed the Sizzler, also invented some little hydrofoil-type things that clamped onto the hulls to give them some lift. Very experimental, and I don't remember anybody getting very enthusiastic about the idea, so I don't know whether they actually worked or not.
Paul also designed a simple roller-furling device for the jibs, just involving a PVC tube attached to a plastic drum. Worked great. He also designed the ginpole-type mast-raising system for the Trailex trailers, and we sold that as an optional accessory.