Hi - Thanks for your responses. A new problem has developed. My 50 HP Perkins has been acting up lately and seems to bog down after 1 hr of use. The temperature guage goes to redline and I don't seem to be making any headway - 4-5 mph. I just had a mechanic look the boat over (sea trial) this afternoon and he said the water intake wasn't blocked and the engine seemed to be running correctly. He suggests taking out and cleaning (or replacing) the heat exchanger. Any idea where to find a replacement unit for my boat? Also, anyone know where to find a mechanic near Tarpon Springs, FL that charges less than $100 per hour. Thanks.