Well today proved a point. It was one of those days when I decided to go out, and Mrs Nature added about 15 knots to the wind between when I decided to and when I actually went. I was glad to have the lines already rigged on the boat as after launch I had a job getting close enough to the pontoon and staying there long enough to grab anything to tie up, not often I put all three lines on the boat when I'm only leaving it for 5 min to pull the trailer out.
After I had been out for quite a while, I glanced across at the port side to see the forward line had worked loose where the end was tied off to the A frame, and become detached by the bouncing around (it hadn't been used today as I was starboard side to - in fact it probably hadn't been touched for a couple of months) and it was trailing in the water from the forward cleat.
About two feet short of the prop, so no problem
Not a day I would have wished to have had a prop/rope incident. Shorter is better