By 
“I stupidly left the plug out when I put my boat in this year, Alex. Is there a way of making sure that this never occurs again?”
Sometimes the simplest method of solving that problem is the best. When you pull your boat from the water and unscrew the drain plug, take a tie wrap and attach the plug to the steering wheel. Even if you put the boat in the water and forget to put the plug you will soon see it hanging from the steering wheel instead of where it should be back in the boat.
