Was looking for a boat cover for my 20' glastron cvx-20 sprint. I'm having a hard time finding something like a basic, nylon boat cover. I DO NOT want or need a breathable boat cover. When I'm not at the lake my boat is stored indoors so the only time I will ever have the cover on it is while trailering if it's raining or if it starts raining while at the lake. My concern is something that will keep 100% of rain water out of the boat. All the boat covers I see for sale are all made out of fabric. Cotton, polyester, etc. After having owned a fabric car cover and knowing how poorly they keep out water I'm kinda gunshy about buying a fabric boat cover for what I want to use it for. Are the fabric boat covers not as bad as the experience I had with a fabric car cover?