I am recarpeting my boat (16' sea nymph). I am comfortable with the project but I am not comfortable with the type of carpet to select. I have been shopping around and found 2 types I like. 1. HomeDepot has a 24oz rubber backing Shaw brand for $1.05/Sq Ft. The other is from a carpet store and it's also Shaw Indoor/outdoor but it's not rubber backed and is 18oz. for $.44/Sq Ft. Is the rubber backing a must have?