It's much more difficult to recover a person from the back of a boat, especially a sailboat. The helo crew will usually tell the victim to enter the water. And sometimes, after many hours of seascikness and thinking about death and struggleing to keep the boat afloat the crew will leap from the vessel as soon as they hear the rotors approaching. Then the aircrew has to keep track of several drifting bodies while the swimmer puts them in the basket one at a time.
The rescue swimmers train here. They run by my office in the morning. Kevin Costner did not even come close to capturing how cool those guys are.