I have never seen a jute backed marine carpet, always rubber regardless of sub-floor. There are several good reasons to use Marine Grade rubber backed carpet, adhesion to the subfloor with Marine grade outdoor adhesives, mold & mildew resistence, and formability. There are a number of areas where the carpet is "formed" or molded around things, the rubber backed carpet is easier to do this with. I guess if you were carpeting a large flat surface like a pontoon boat deck it might be ok??