As to the last post, a friend of mine was launching his boat on a Monday (I was back at work, as were most people, I presume - he claimed no witnesses other than his dive buddy.)
He backs the boat into the water, and taps the brakes to get the boat off. NoGo. Pull up a bit, back in, hit the brakes harder. Still NoGo. One more time, with a bit of speed, and everything in the back of the pickup slides out, and is floating the ramp area. Get out, recover equipment bins, several dive cylinders, a cooler (which, conveniently, has shed the weight of all the contents), a couple of duffel bags of dry clothes (well, used to be dry, anyway), etc.
Look at the boat, and realize the trailer is not sitting flat. One wheel is suspended mid-water. Wade in, and see the problem: One transom strap still attached. Release transom strap, dodge trailer as it sinks to the bottom, dodge boat as it springs back to it's normal float line, pull out and park, go diving.
Sometimes, my friends are not the sharpest knives in the drawer.