breathable boat cover

is there a boat cover material that is also breathable similar to goretex? i assume goretex would be too expensive to build a cover out of but is there something similar to cover a boat with? the reason i ask is because my boat got rained in this morning and when i dropped it off at my covered storage i had to put the cover on the boat. its the only way to keep the cats from getting in the boat while in storage. my cover will keep rain out, but im wondering if it will also allow moisture to escape from the wet catpet.