One other possibility not mentioned and common on older bravo setups; the lower 2 bolts on the transom assembly were "annode bolts". They corrode sacrificially and go away loosing all of there clamping force. Worse case is they snap off and you have a large hole. Usually though they snap when you put a wrench on them to try and snug down the transom assembly due to mysterious water in bilge.

BT

If you didn't notice a reduction in performance while you were running, perhaps the water was there for the whole trip. Boats kept on a trailer, or on a storage rack outside, sometimes manage to fill-up with rain or washdown water that travels to the bow if the boat is at an unnatural angle.
Chris is right; why didn't the automatic float switch empty the boat when the water rushed to the stern?

Put the boat back in the water with a dry bilge. Lean way over the engine and see if water is leaking in the transom plate. If everything stays dry, start the engine and watch to see if engine cooling water is what is leaking.

Good Luck and keep us posted to what you find. I've been around boats for 37 years and I STILL find new things!

thanks everybody,for all the responses saw my buddy this afternoon, this is a good one... first the float switch didn't go on cause he took it out when the last pump failed??? figured he didn't need it cause its on the trailer and he barely uses the thing???? needless to say he's installing a new one now, now about that water, he took the boat out and checked several of the problems you guys mentioned, i assumed (after reading your posts) it was bellows, apparently though the upholstery on the sun deck has a few cracks in the vinyl, and after sitting (unused) for a while water had accumulated in it so once it was in the water all the water soaked into pad drained into the bilge!! thanks again for all the replies