Its an old boat (1978) and Ive had her forever. Last weekend I was out with my son and on the way in the boat kept making a popping noise. It sounded like it was coming from the rudder assembly or the very back of the boat. We were going down wind and in light wind so the boat wasnt stressed. I couldnt "make" the noise moving the tiller or sails. It would just make a pop sound occasionaly. Like something was loose. On the trailer, the pylons seem anchored. The sound was not metallic in nature. Any ideas?