Choosing a yard to build a new yacht?

The problem with putting an Aluminum or s/s shoe over the fiberglass keel would be that it would actually weaken the hull. The Aluminum (of appropriate thickness) or stainless steel shoe that you would put over the Fiberglass keel does not flex or bend nearly as much or as easily as the fiberglass behind it, so in a large enough collision it would try to rip or crack the fiberglass right apart where it is jointed. It would do so even if the fiberglass is super thick at the joint.......in a lot of cases.....think of shooting a hull with a truncated steel armor piercing round at 400 FPS, it would go through most hulls even at that slow of a speed. Now shoot the same hull with a plastic airsoft bullet of the same weight and same speed and it wouldn't puncture the hull because the plastic would give first. A fiberglass hull when built properly, especially with the right coring material, can take quite a bit of impact before breaking, not so much as steel, but it is indeed surprisingly strong when built correctly. Ive seen 25' boats fall off of a boat trailer going 65mph onto concrete and have very little damage to them. I've also seen trucks trailering boats stop short and see the boat come foward on the trailer and completely destroy the truck towing it and aside from surface scratches be ok.

I agree with Olderboater, steel hulls of appropriate thickness are not impervious to damage, but they are much more resistant to it than FRP and aluminum.

Worrying about this whole hitting something in a 100' yacht traveling around the U.S. and Carribbean, is a bunch of BS anyways that shouldn't even be a worry or concern. Let me rephrase that, of course it is always a litle bit of a worry, but not to the extent that the OP is putting on it. It's like buying an armor plated Humvee to drive around in everyday because you're worried about getting killed in a car accident, then trying to get it to perform like a Cadillac Escalade. The OP is not talking about running the boat anywhere near ice burgs and glaciers.

The hollow keels are actually better or cored keels as long as the hull is sealed where they are jointed. The keel absorbs the impact and crunches, leaving the hull behind it to be sound......sort of like the technology of crumple zones on cars.