Saturday I noted that foiling trimaran l'Hydroptère set new world records for 500m and 1,000m, exceeding 50 knots. Wow. Here's a video of the record run, well worth watching for sheer coolness. I cannot stop watching it.
Some notes to add on this amazing vessel:
It is a real boat, on real water. It can go any point of sail, and seems to be able to handle fairly rough open water in the ocean. Sometimes one-shot speedboats built for setting record only go on one tack and only in flat water.
The rig is pretty "normal". Sure they're flat carbon fiber sails, but the setup is a basic sloop, nothing weird going on at all. Sometimes people think to go 50+ knots you need hard wings or something.
The design of the hydrofoils is really clever, because they counteract heel as well as lifting the boat out of the water and reducing drag. As the boat heels, the lee foil become more horizontal, generating more lift, and the weather foil becomes more vertical, generating less. The resulting forces balance the heel. As a result you see the boat powering along staying flat, despite gusts of wind in the 20-30 knot range, and an apparent wind of over 60 knots.
The design of the rudder is really cool, it has to act as a lifting foil as well as steering device. You can see it clearly in this picture of the triamaran, after it turtled going 60+ knots!
Perhaps we could say that for this design, the sky's the limit :)