The scene of Crown racing a catamaran replaced a similar scene in the original script (and the original movie) that was set at a polo match. Director John McTiernan deemed a polo match to be too much of a cliche, and wanted a scene that conveyed more action and excitement, and not just wealth.
The catamaran that Thomas Crown is seen racing in Long Island Sound is a D-Type Catamaran, an extremely fast and highly unstable yacht design from the 1980s. The D-Type’s were designed by California based aeronautical engineers to try to break inshore multihull speed records. Today there are only a handful of them left in the world.

Amazing footage! Great find! Thanks for sharing it.
Note that when Pierce Brosnan goes to grind the winch, it’s not loaded with a sheet…
How do they steer those boats? I don’t see rudders.
@ Tom: Actually there is a line going to the winch. Not sure what it is and whether he is actually working it (it certainly is not in the self-tailer) but it definitely is visible very briefly as the camera pans down.
@ T.: There are rudders. In fact, each boat has two rudders (one from each hull). Quite clearly visible at various points of the video, including 0:10, 0:26 (very briefly), 0:31, 0:39, 0:57, 1:31, and 1:42.