You're told to never let go of your equipment. At a minimum, it saves you from a long swim which saps your energy. Also, floating gear is a hazard to other sailors, as well as the probability of it getting smashed into a sandbar increases when you're not holding on and able to at least resist the currents desire to take it where it shouldn't go.
These shots from the Old Lifeguard Beach session in Hatteras during Loopfest:
Well, sometimes there just no way around going for a swim! Nice Bill!
You especially don't want to let go of the boom while tossing forwards. Ken Kellar during the Main Event
Sprecklesville, Maui Feb '08