Ten Commandments of boat maintenance

I just found my notes from a diesel mechanics course I took at Mack Boring in NJ years ago. According to Larry Berlin of Engine City Technical Institute, the following points are the critical things to do with a diesel engine, specifically a Yanmar:

1. Follow the engine manufacturer's Operations Manual. 
2. Get a service manual. Operations Manual tells you what. Service Manual tells you how. 
3. Keep fuel oil (diesel) tank full at all times. Top off from 5-gallon spare to keep condensation down and keep algae from growing. 
4. Fill water in lead acid batteries even if they are labelled maintenance free.
5. Clean wire connections with wire brush or sandpaper, put on dielectric grease, and cover with electrical tape.
6. Tighten all nuts, bolts, and hose clamps at 50 hours. Every 50h retorque cylinder heads. Head gaskets blow at about 400-500 hours if you don't retorque the heads and adjust valves. New service manual (15 years ago) says its no longer needed to do. Tighten hose clamps at least twice a season. 
7. Season definition to the boat manufacturer is 6 months. If it says every 100 hours and you only used it for 10 hours, follow the season recommendations.
8. Warranty is transferable to a new owner but it has to be certified by a Yanmar mechanic that nothing has been changed. 
9. Putting an elbow on the exhaust to accommodate a generator could put high back pressure on an engine and invalidate the warranty. 
10. Change oil when it's hot. Run engine 15 min, let stand 15 min, then suck oil out. It will keep particles suspended. Put 2 quarts in, run the engine a few minutes, let sit 5 minutes, then top off to full mark on the dipstick. Don't just put in 3 quarts. (There's no drain plug on GM series and on a sailboat its hard to get to the drain plug. Go through dipstick tube to suck out.)

Note: HM engine has a breather cover on the crankcase ventilator. It creates positive crankcase pressure. The wire mesh net gets clogged and causes the dipstick to pop out. It is misdiagnosed often and causes people to rebuild the engine. Need to remove and clean the wire mesh net. Remove valve cover to access breather cover. 

• breather cover
• o ring
• wire mesh net  -- this 
• shelter plate 

Note: foam inside blower needs to be cleaned every year. Water rinse and dry. 

Tip: To test belt, press with thumb on the longest section. It should move no less than 1/2 inch no more than 3/4 inch. Use belt tensioning tool about $3 from an automotive shop. Use Mitsubishi high-end industrial belt - metric.

Tip: Get a remote start switch. Better than using a screwdriver - no sparks. 

Tip: Do not spray engine with WD40, just attracts dirt. Scrub engine before out of water. Start the engine and let it dry. Paint rust spots. DO NOT spray near batteries. Double clamp everything from seacock back. 

Tip: Do not use an automotive battery charger. Can blow up the boat and invalidates insurance.

Remote start switch

Haha, I should have been reading this every year. At least I bought the service manual and have referred to it many times over the years.