I have a 1981 Catalina 38'. I have owned this boat and sailed it more years than I can count. I love going to Catalina Island on nice summer days but I have a problem. My boat is located in San Diego, and usually the direction to Catalina for me is up wind. That makes for a 13 hour boat ride to get there. The main problem is that when I rev the engine to around 2000 rpm, the whole boat starts to vibrate and make a really load noise. A lot of people have told me this is probably a cavitation issue, however I just don't believe that. This boat has made that racket from day one, and I have a hard time believing that a brand new boat would rattle so much. This problem not only makes the boat ride unpleasant, but causes for a slower ride to control the problem and I assume it is doing damage to the engine and prop shaft as well. Please Help!!!!!