I was about two-thirds of the way home when we hit something (it was raining and I had my wind screen down). At first I thought it was a piece of debris but I also knew that whatever it was it was large. I pulled the throttles back, turned around to see what I had hit and to my amazement in the prop wash was the dorsal fin followed by the body of a very large shark . It only took a second for it to disappear back under the water and I never got a chance to I.D. it but I suspect it was a large bull or tiger shark. We circled back over the area and could see a large amount blood and the body of the shark down on the bottom. Never heard of nor have I ever hit an animal like that in a boat driven in relatively deep water as we were. Wierd!