a device for rescuing people at sea, consisting of a piece of strong canvas with leg holes suspended from a life preserver that is run along a rope from ship to shore or to another ship
See breeches buoy in American Heritage Dictionary 4
noun
An apparatus used for rescues and transfers at sea, consisting of sturdy canvas breeches attached at the waist to a ring buoy that is suspended from a pulley running along a rope from ship to shore or from ship to ship.