My 41 sun dancer is 14 years old with 400 hours on the engines. I've owned her for 6 years, I am the third owner. To my knowledge the heat exchangers have never been replaced. My local Cat dealer says they should be replaced every 6 years. What say you all? Also, my slip has an awful starboard wind, which drives me crazy when I dock even though I have a bow thruster. What about a stern thruster? Are they effective? Many thanks.