Thanks for the input Dave, Mike.
Very good point about the capsizing, not a great idea! I have an outboard so engine kill cord is always on, but wouldn't prevent me falling out.
I have ordered some safety lines which I will clip to the hand rails using the D ring on the life jacket (a reminder for me to actually put it on). Ok so it won't keep me IN the boat, but will at least keep me attached. I like the webbing idea, especially as I have several reels of the stuff, may look into this in the summer!!