Sorry jwalker, I did actually ask the boat builder to implement this on your recommendation.
But, by the time you made the comment, the rubber had all been stuck to the tube, and the boat builder expressed reluctance to make changes. In fact, he advised that it was in his expereince neither necessary or appropriate. Sadly I accepted his advice, as there were other more pressing issues such as centre throttle (which I wanted for safety reasons), which he was again not very positive on, where I put my foot down.
I did not disregard your advice. Far from it. In fact many items on the boat have shamelessly borrowed from in particular yours and Richard B's kindly given advice, which I continue to appreciate.
So please advise me. What to do now? Get him to remove the exisitng fairlead and put on a full one? Add a lower part to the exisitng fairlead? Add an additional pad to each side of the lower fairlead as I suggest above?