I've been using this one: http://www.clcboats.com/shop/products/boat-building-supplies-epoxy-fiberglass-plywood/boat-building-tools/beading-saw-with-woodpecker-tooth.html

I really like it, though it's the only one I've ever tried. It seems like the 'woodpecker tooth' might actually be able to start a 'plunge cut', though I've never fully tried it. It still cuts well after one wood hybrid, and 3 SOFs (big cuts there, tapering the gunwales, er, several times), but, when starting cuts, it's starting to feel less sharp.

I also tried the Bonzai saw, potentially for cutting hatches, but did not care for it: http://www.clcboats.com/shop/products/boat-building-supplies-epoxy-fiberglass-plywood/boat-building-tools/bonsai-saw.html