Warren I would say this is more than a bit. I race RC boats and sound is a concern as we have rules on max sound. One thin we have found that quiets the hull noise a good bit is lining it with the camping mat foam. Its about a 1/2" thick and also acts as floatation. One other thing that may be worth a try is the gray egg crate foam that a lot of stuff comes packed in. The shape is a lot like the professional acoustical foam they sell. Should keep the sound waves from bouncing around.
Jimmy