Rub Rail Cleaning
I work for the company that probably made the rub rail that went on your boat. As a Hunter 37 owner I use our technical people for questions like this.First of all the rub rail is not rubber it is make of Flexable PVC and extruded.I went to our technical people as aked the question. Their response was that a good detergent and elbo grease should do the job. If the dirt is rubbed into the plastic, it probably would be inbedded into the rub rail.I am going to try an experiment at home and see if once you sand down a portion of the rub rail can the original luster be achieved by adding heat from a heat gun. Don't know if it will work but will try and I will report back.