Some interesting stuff about racing boats.
The sails are made on a shaped mold. A mylar panel is laid down, then graphite strands are stuck onto the mylar along the load-paths, then another layer of mylar seals the whole thing together. The graphite strands take the loads in pure tension, allowing the sail to maintain perfect shape. On the downside, the sails are fragile and have a limited life. I think that’s a delamination between the mylar sheets in the middle of this picture (Edit: It’s not. See the comments section for discussion of this entire paragraph which obviously should have been longer and more complete but it’s only yammering on the internets so we’ll just leave it as is).
This is the port ama of Orion. The curved thing running vertically through is the moveable foil. There was some discussion whether it pulls down on the windward hull, or lifts on the leeward hull, or both. I still don’t know. A friend watched the boat motor into the marina. He said it was very apparent that the boat didn’t weigh very much – it bobbed like a cork in the chop.
Edit: Went and had a talk with the crew. The foils lift up on the leeward hull. The angle of attack can be changed, but not while the foil is loaded. They do not use water ballast to balance the sailing forces, although Mighty Merloe has a water tank in the bow for fore/aft trim.
This is the second-place tri, Mighty Merloe. The orange blade sticking out of the center hull is the dagger-board, used to balance the sail loads so the boat doesn’t just drift downwind. It’s stunning how small the underwater foils and rudders are, but when you average 20 knots, like these boats do, it doesn’t take a lot of underwater surface area to develop incredible forces.
Apparently the two trimarans were racing side-by-side until the starboard foil snapped off Mighty Merloe. The pieces are still there, probably wedged into the hull trunk. They still finished strong even though they were only fast on one tack.
Several of the boats will also race this week in MexORC, a series of big-boat buoy races here in Banderas Bay. Others spent Saturday stowing the expensive graphite sails, fitting cheaper and more durable Dacron sails, and loading fuel for the trip upwind back to San Diego. Several boats will carry extra fuel in plastic drums lashed on-deck.
A good way to get an idea of the tech involved with these things is to look at the graphite/epoxy wheel. Part weight savings, part race-boat bling.