The idea of understanding continuous duty is an important one. The way in which a boat diesel is run strongly affects its life cycle and maintainance needs. A few rules to follow:
1) Clean fuel is paramount. That requires vigilance at the deck
fill (a Baja
or similar filter to keep dirt out) and a decent fuel/water filtering setup prior to getting diesel to the engine's own fuel filter
. In the broader sense, you need to keep your main tanks
free of containments. Many long-term cruisers install a daytank that has nothing but post-filter fuel in it at any time, and therefore represents a "known to be clean" reserve, even if you have some sort of ingress and/or bad diesel.
2) Speaking of ingress, consider moving the tank vents off the side of the boat to someplace farther from the water.
3) Diesels will run optimally at a certain RPM. By optimal, I mean in terms of fuel economy, and in terms of running at 75-80% of rated output. They also like a certain amount of heat throughout the block, which is why truckers in cold climates leave their engines running, pollution be damned. Ideally, you want to switch on, run at 2,200 RPM (or whatever) for a few hours, and never touch the throttle. That heats the engine, makes the metal parts mate tightly and aids in proper lubrication. So I prefer to sail slowly at times rather than motor
for 10 or 20 minutes, and I also in cold weather
only gradually increase the throttle until my temps are nice and warm. The engine seems to like it better that way.
4) Cooling can be a black art. Most of my engine problems have been related to backpressure, little busted piston valve springs, and half-busted waterlift mufflers. The problem, of course, is that the engine cooling circuit is at or below the waterline, and the raw water
(assuming you have a heat exchanger) is ultimately being pushed uphill to get, with the exhaust, out of the boat. That's a recipe for disaster unless it's fully understood. One of my decisions is to get rid of the siphon break and just to run a simple hose out to the deck
. Easy for me: I have a steel
with the exhaust going out one side. But the idea of having the fuel and water tank vents and the siphon break vent open and on the centerline near the "top" of the boat is not a bad one, and is worthy of consideration.