“Everyone behaves badly--given the chance.”
― Ernest Hemingway
On my wife's boat (Key West 1720) we leave it strapped, back into water, then release. My boat, a 25 foot Cobia WA, gets unhitched totally. I have to back it in quite deep before it even begins to move off the trailer, and even then I have to gun the engine in reverse to get it off the trailer. It has bottom paint and the bunks are carpeted and the boat is somewhat back-heavy, so it sticks like Velcro to the bunks. I also back up slowly and the ramp isn't too steep.
Alex from GA said:
My buddy and I launch his bass boat several times a week. We take all the straps off, I back it down the ramp until the lower unit is in the water and when he starts it I back it a couple of more feet and slam on the brakes. When we're taking it out I back it down the ramp the right distance, he drives it on the trailer and when the bow hits the chock I pull it out slowly. Once on a flat surface we tie it down and go home. We've been doing it this way for over 15 years without a problem.
I had two boats to slide off the trailers onto the ramps. The first I detached the winch strap and safety chain. The second I detached the winch strap and left the safety chain attached. Partially straightened the hook on the safety chain and the boat slid off the trailer onto the ramp. I leave both attached now until the trailer is in the water and ready to launch. Very embarrassing winching the boat onto the trailer from the ramp with an audience. Fortunately very little damage to either of the boats.