It is important not to rely on the winch to hold your PWC over extended periods, and especially when you are cruising down the river or lake in your houseboat which will put additional stress on your winch. You will want to add a secondary tether which can be a short chain or rope that is attached to your railing or to the winch frame. It doesn't have to be a heavy duty rope...something similar to a ski rope will work great.
The simplest way to do this is with a short rope that connects your winch hook to your winch frame. We call it a "Loop Tether".
As you can see in this picture, it is a simple loop that is connected to the hook. The other end fits over the portion of the winch frame where the fairlead is normally bolted.
1) Winch your PWC up as tight as you can with the nose of your PWC up against the Winch Frame.
The loop-tether will stay with the hook where it will always be handy.