Ive been using these for a while, Just thought I would share. They barely fit over mine (belled ends), and the you can tie a slipknot on the drawstring. I have pulled my boat with them on and have never had one come off.
The best part is you can "accidently" turn the motor over with them on, blow holes in them and then you have an excuse to buy two 750ml bottles of the worlds best whiskey (IMHO).
Of course if you are not a crown royal drinker, you can just send me 60 bucks for a set of just the bags, Just kiddin.