You can rent small catamarans (Hobie 16 for example) at a couple of places on Orient - walk to where you see them laying up on the sand :>) Don't know about rates, or availability elsewhere on the island.
Rent a laser at the water center at Club Orient every year. Some new boats at about $20 US per hour.
They also have larger cats. Have not seen larger monohull.
Very reasonable and helpful, but they do not like to rent in light air? <img src="http://www.traveltalkonline.com/forums/images/graemlins/Groovin.gif" alt="" />