Having a frustrating problem with being able to get decent speed out of my cobra..has a johnson 200 venom and I'm running an OMC shooter prop 13x25p...tried a 14x25p new prop and hole shot is better and lots more torque but only a little more speed topping out around 50mph, motor is strong and middle of prop is about 3" below the pad....someone suggested the flotation material might be waterlogged...how can I check this on a cobra? Whats a good location to check from?