Scenario: They started the engine to run the generator for the computer. The wind was light so one decides to go for a swim before dinner, he has some type of problem in the water (heart attack, shark, jelly fish??) and needs asistance to get back in the boat, both the others jump in to help, a breeze comes up and the boat sails away, or they just cannot climb back aboard because in their hurry to assist their friend someone forgot to lower the ladder?