My boat is old and has the typical bench front and rear seat. The original seat cushions (long gone)were simply upholstered rectangles which lay on the seat portion of the bench. The seat backs (also long gone) actually snapped to the bench back. Soon I plan to have an upholsterer fabricate new seat and back cushions. I have surfed the net and found a myriad of vinyl types and am very confused. What is the best type to use? Also is conventional foam rubber the best material for the cushion?