Generator maintenance for boaters

22nd November 2021 Elena Manighetti

Generator maintenance for boaters

Some boaters rely heavily on a marine generator for their energy needs. Yet, it’s one of those pieces of gear that malfunctions often, especially once you’re anchored in a beautiful remote bay, far from any chandlery or dealer.

We have put together some tips to help you care for a marine generator, which will hopefully help you decide whether investing in one is right for you. It’s worth the expense if you use it regularly during the boating season and you have the time to look after it properly. We talk about this towards the end of the article.

Disclaimer: Don’t rely solely on this article to look after your generator. You’ll need to get familiar with your unit’s manual, once you have one. Most generators are similar, but some require a slightly different maintenance routine. Follow your manual to start the unit off for the first time.

What to do after the off-season

After a long period of inactivity, you’ll need to service your generator. This involves:

  • Ventilating the locker in which you store it

  • Cleaning the unit (and all its components) and the surrounding area

  • Changing the oil and filters

  • Replacing the zinc

  • Inspecting the belt to see if you need to fit a new one

  • Charging the starting battery fully

  • Tightening all the hose clamps, connections, and fittings

  • Inspecting all electrical connections

  • Examining the thru-hulls and tightening them

Finally, follow the procedure for pre-start checks reported in the unit’s manual to make sure you haven’t missed anything.

Once that’s done, start the generator and check for any leaks and weird noises. It’s best to make sure that you can fire it off from all onboard control stations if you have more than one. 

Then, turn on all the electrical loads you plan to use to check that the unit isn’t overloaded and that it can handle the load it’s rated for. If you intend to use more than one appliance at the same time, turn them on simultaneously. 

It’s also a good idea to run the unit at 80-90% load for half an hour to make sure that the cooling system is working correctly. Listen to any noises the generator makes and watch for black smoke coming out of the exhaust.

Generator checks while in use

Once you start using your generator, you will need to keep a close eye on it to keep it in good working order. 

Each time you use it: 

  • Inspect and clear the seawater strainers of any waste so they don’t clog

  • Make sure no component has come loose underway

  • Check that all air inlets and outlets are free

  • Examine the fluid levels and look for any leaks

  • Inspect belt tension, oil and coolant levels, and the condition of the primary filter.

The best and easiest way to keep your generator running smoothly is to use it regularly. Run it at least once a month with a load to prevent gas from producing gum on the carburetor.

Keep track of operating hours and performance, so you can spot a problem as soon as it appears. Check how often a service is needed in your manual. You may need to perform another service (or two) during the boating season. If you plan to go on long trips, make sure to fit the service in before you leave. You don’t want to risk it breaking while you’re away.

Generator spare parts to own

If your generator is showing signs of malfunction, such as not carrying its rated amps, you’ll need to go to an authorised dealer, so they can repair it before the problem gets worse. It pays off to have spare parts at home, so you won’t have to wait for the dealer to order them.

Here are the recommended spare parts to own:

  • Primary and secondary fuel filters

  • Oil filters

  • Air filter

  • Seawater pump impeller and gaskets

  • V-belts

  • Thermostat and gasket

  • Glow plug or spark plug

  • Injector and washer.

If you’re going somewhere remote, it’s also useful to carry:

  • A set of injectors

  • Copper washers

  • A set of glow plugs

  • A fuel lift pump

  • A seawater pump

  • A spare solenoid.

Maintaining a marine generator isn’t straightforward. You need to conduct regular checks to keep it running smoothly and replace some parts of the unit regularly. 

Should you buy a generator for your boat?

Generators allow you to keep the heater, AC, electronics, and appliances running while the main engine is off. If you can find an alternative method to produce energy that is less expensive and time-consuming to maintain (such as a solar system or a wind turbine), you may want to consider it first. 

Generators have a much bigger output though, so if you have certain energy needs, there are no alternative solutions. 

When you decide you’re ready, select your unit well based on the output you need - you don’t want a generator that’s too small or too powerful. Make a note of the watt ratings for all the devices you need to power. Decide which appliances will be on at the same time and add up their ratings. Choose a generator that can supply a little more power than that, but not a lot more. For convenience, go for a unit that uses the same type of fuel as your engine(s). 

While you might be able to install the unit yourself, it’s best to hire a professional to do it, so you know it’s done safely and in accordance with electrical codes. Boat fires can easily start with a small spark and are often deadly.

Make sure to run the generator often during the boating season and to turn it on every time you go check on the boat in the off-season. A well-maintained generator will run smoothly for years. It just takes a good amount of care.


Download the Deckee app from the App Store or Google Play to plan your next boating trip. Check the weather forecast and look up the best anchorages and marinas near you. You can set reminders to help you remember to test run and service your generator, too.