Many powerboat cruisers operate at speeds and loads far below the levels that engine manufacturers expect. To maximize fuel economy, many of us cruise at displacement speed (less than 1.34 times the square root of a boat’s waterline length). That kind of speed requires relatively low rpm, and the load on the engine might be below 25 percent of its capacity.
On older engines, this kind of sedentary life can be harmful. But what about with modern common rail computer-controlled engines? Does speed still matter, or are such problems no longer a concern?
In the spirit of those who have busted myths throughout time, we set out in search for a definitive answer.
THE PERILS OF AN EASY LIFE
Many passagemakers are fitted with engines that have just enough extra horsepower to stem a tide or buck the wind, and that are never intended to go much faster than their displacement speed. They are fuel efficient, and they allow for great range. Most of the time, these engines are operating at 70 percent to 80 percent load
