Yeah, I know that its just that all he needs is one exploratory bite and then its all over if he can't get back to the boat fast enough. That white would eat him then ask for 2nds.

A Great Whites bit pressure isn't actually all that much stronger than a Human bite. Its just that the White can exert that same pressure over a much larger area, and its got those lovely teeth that cut flesh like a steak knife. Combine the two and its frightening what a single bite can do.