(actually) I think he's aft (or daft) in the boat, and that's the handle for an outboard motor.
Im sure that is the handle of an outboard trolling boat. What i was interested in was the right foot there and no left foot showing, so either the guy is doing a heck of a splits or he has his left foot in the water. Im thinking that it is in the water and he is pushing the boat along in shallow water with his foot. There is just something fishy about the cut of the picture. It is a small part of a larger picture and im sure the photographer wanted to make sean penn look as good as he could, and putting that foot in the water with the water probably being only two feet or so deep would make penn look more the idiot than he does now.