Your narrowboat goes through a lot, especially if you’re a live-aboard narrowboater. That’s why you need to protect it. From daily inspections to end of season checks, looking after your narrowboat will save you large sums of money in the long run. The below steps cover everything you need to know about narrowboat maintenance.


Daily checks

For your narrowboat to remain in good condition, the best approach to narrowboat maintenance is ‘little and often’, and you should carry out certain routine checks every day.


Checking your narrowboat’s oil is arguably the most important daily check you should carry out.

Failing to check your oil frequently enough could result in:

  • Leakages
  • Dirt or carbon build-up
  • Your engine overheating
  • Engine failure

Overfilling or underfilling your engine or gearbox can be equally detrimental to your vessel, which is why this step is so important.

You need to check your engine and gearbox’s oil levels every day, or every eight hours your engine is running if you’re a more occasional cruiser.

But, if you’re not keeping track of exactly how many hours your engine is running each time, don’t worry. Knowing when you need to change your oil is really simple.

Provided the engine has been running for at least an hour, use a dipstick and then look at the colour of the oil. Here’s what you need to know:

  • If your oil looks clean, you don’t need to change it.
  • If it’s a milky or opaque colour, there is too much water in the oil, and it should be changed along with the oil filter.
  • If it’s black, your engine or gearbox is most likely overheating, or the oil has collected carbon and dirt and needs to be replaced along with the oil filter (more on this in the Annual checks section below).

If you’re unsure about the most suitable oil for the vessel’s engine, you should always refer to your narrowboat manufacturer’s guidelines.

Electrics and wiring

If there are issues with your narrowboat’s electrics and wiring that you haven’t picked up on or inspected, it could have several serious implications.

For one thing, your ignition may cut out if the wires are loose or corroding. Another risk, of course, is the potential cost of getting your narrowboat rewired if an issue you hadn’t spotted persists and gets worse.

That’s why you should check for loose or disconnected wires before every trip you take on your narrowboat.

You should also use a water-resistant spray or petroleum jelly to stop damp getting into isolators and block connectors.

If you need to replace any wiring in your narrowboat, The Recreational Craft Directive provides guidance on rules and regulations around installing electrical systems on small craft. Unless you’re totally comfortable with electrical systems, you should consult a qualified electrician about repairs in the first instance. The below video provides some valuable insights into narrowboat electrics.

Hopefully you don’t need to use a specialist too often, but if you do require expert advice, check out this list of specialist electrical service engineers.

Drive belt tension 

A drive belt (or fan belt as it used to be known) is typically connected to your boat's alternator and water pump via the crankshaft pulley at the bottom of the engine.

You need to check the tension of this belt every day, as if it starts getting ragged or stretched it could cause major engine damage.

There are a few tell-tale signs that your narrowboat’s drive belt may have insufficient tension:

  • Listen out for a squeaking sound. This is a tell-tale sign that it needs replacing.
  • Twist the belt, and if you can see cracks or the edges are starting to look ragged, it’s time for a new belt.
  • You should also look closely at its length – on its longest side, the belt should have half an inch or 12 millimetres of free play. Drive belts tend to stretch with age, so examine your narrowboat drive belt every day, and check its condition shortly after changing it.

The below video visualises where the fan belt is located if you’re unsure and explains how you can replace it if you need to.

Bilge levels

If your bilge becomes full of water and oil, this could leak into and damage your boat's engine. That's why you should check your bilge levels every day.

If you find that the oil levels are too high, wait until you can manually dispose of the oil ashore, as you shouldn’t pump it into the waterways.

Battery fluid levels

Checking the battery fluid levels will help you detect any serious problems with your engine.

You should top up your narrowboat’s battery with de-ionised water and make sure it’s clean before each journey.

Coolant levels

As you’ll know if you own a car, low coolant levels can lead to your narrowboat’s engine overheating, as can a ruptured coolant hose.

That’s why you should check your narrowboat’s coolant levels and hoses each day.  


Monthly checks

Once a month, you should carry out these additional checks on top of the daily ones you’ve already been doing.

Further engine inspections

As you’ll know, your narrowboat engine is made up of multiple components, which would take a long time to check every day. But every month you should set some time aside to make sure everything is working as it should be. This includes the following:

Engine mounts

If you’re unfamiliar with what engine mounts do, they isolate the engine from the boat to make it vibrate less.

If left unmaintained, engine mounts can cause extensive damage within your narrowboat. That’s why you need to check whether they’re functioning properly.

You can check the condition of your engine mounts by looking at the legs of your boat’s engine. Ideally, the nuts of your engine mounts should be touching the engine legs.

However, if there’s a disconnect between the top nut and engine leg, you need to fix this. Tighten the bottom nut until it compresses the engine leg onto the top nut. This will give your boat’s engine the correct alignment and prevent further damage from occurring. This article from the Canal & River Trust explains more.

As with all the tips in this article, if you’re unsure about anything, ask a specialist engineer to do this for you.

Drive plates/gearbox 

If your narrowboat collides with an underwater object, the drive plate (the plate that’s bolted onto the engine flywheel) is often the first thing to be damaged. Your gearbox also goes through a lot, as you’ll know. So, you should check it once a month and get it serviced if need be.


If the bolts that connect your boat’s engine to the propeller shaft are loose, they can be knocked off by the boat’s movement, and it will lose momentum. You therefore need to make sure these bolts are screwed on properly.

Narrowboat battery

After the engine, the battery is arguably the most vital component of your narrowboat. If you take good care of it, the narrowboat battery may last for as long as six to eight years. If you don’t take good care of it, it can fail within a couple of seasons.

Most narrowboats contain two batteries – one for your electric and heating and one for your engine. Therefore, checking these regularly is vital for maintaining your boat’s overall functionality.

We’re pretty certain you’ll have one already but, if not, you’ll need a voltmeter to assess your batteries’ state of charge. The below voltages are a good rule of thumb:

  • 9V – 13.2V = full charge.
  • 6V = 75% charge.
  • 2V = 50% charge.
  • 0V = 20% charge.
  • 8V = battery flat.

You’ll usually be able to spot certain problems with your batteries, as you’ll get a warning light on your dashboard. However, if you’re on an older narrowboat that doesn’t contain a dashboard, you’ll have to regularly check the battery is working as it should be.

On top of the daily battery checks, make sure you:

  • Remove dirt that may have built up.
  • Apply petroleum jelly to the battery terminals to help prevent corrosion by keeping out surrounding air and moisture.

Another important tip for taking care of your narrowboat batteries is to avoid deep discharges – if you discharge your batteries below 50% of their total capacity, this significantly reduces their life. And you should never flatten them completely, as this will destroy them within a few months.

For more information on how to look after your boat’s batteries, check out this article from Practical Boat Owner.

Keel/skin tank

The keel or skin tank (the exact wording varies) is worth checking regularly.

This tank is located on the side of your narrowboat’s ‘swim’ –the curved side section at the back of the boat. Its job is to cool the engine coolant which is circulated through it, and it develops pockets of air naturally. It’s designed to allow a build-up of air, without affecting the cooling system’s performance, but it can only take so much air build-up before it stops the coolant flow.

So, in order to prevent your narrowboat engine from overheating, you need to regularly bleed the air from the keel tank.

The hull

Your narrowboat’s hull is the part of your narrowboat that will likely suffer the most wear and tear. So, every month you should cast a close eye over it, looking out for rust and corrosion. Make sure you don’t forget the inside of the hull – the inside isn’t exempt from rust or corrosion, either.

While inspecting your hull every month will ensure you spot any issues before they become serious, you’ll occasionally need a professional inspection because much of the hull is underwater. Once every four years, you should book an inspection with a qualified marine surveyor who can check for other issues such as cruising damage and hull quality.


Each month, you should make sure that the gas flames in your water heater and boiler are burning clean blue. If they aren’t, you need to call in a Gas Safe registered engineer who is approved for liquefied petroleum gas on narrowboats.

Wiring and piping

You should check the electrics and pipes in your boat for signs of wear and tear and leakage.


Annual checks

The below checks should be carried out every 250 hours that your narrowboat engine is running:

Drain antifreeze and coolant

This step needs to be taken with care, as antifreeze and coolant are very damaging to the environment and water. Coolant is especially dangerous as it’s toxic to wildlife.

So, you need to take the utmost care when draining the antifreeze and coolant from your narrowboat to ensure none of it ends up on the canal or river. This article explains more about how to drain antifreeze and coolant from your narrowboat engine responsibly.

Check nuts, bolts, and fastenings

This is a routine check but it’s important to ensure that all of the bolts and connections of your narrowboat engine are tightly secured. You also need to make sure they’re clean and dry and aren’t showing signs of corrosion.

Change oil, air, and fuel filter

We’re almost certain you know this, but filters are essential to keep water and foreign particles out of your engine. That’s why you should change the oil, air, and fuel filter at least once a year.

The main reason for changing the oil filter is obvious – to prevent clogging and allow more oil to pass through the narrowboat’s engine, thus avoiding the potential for severe damage. Changing the fuel filters allows air into the pipes, while regularly replacing the air filters ensures the free flow of air into the engine and optimum performance.

If you change your oil filter, make sure you apply oil to the rubber seal around the end of it and secure it well.

The below video explains how to carry out an oil filter change on a narrowboat.


Specialist narrowboat insurance from Insure4Boats

In addition to taking the above precautions, you also need to protect your boat with specialist narrowboat insurance.

Our insurance covers your narrowboat against theft and damage, and we offer a wide range of optional extras, including frost, contents, and personal accident cover.

Insure4Boats narrowboat insurance policies also include £3million of Public Liability as standard in case you have an accident on the waterways or cause damage to another boat.

Insure4Boats is part of Ripe Insurance and, as part of the Ripe Guarantee, we promise to provide you with great cover and exceptional service at the best price. We let you tailor your policy, so you’ll never pay for more cover than you need.

Get an instant online quote and protect your narrowboat today.



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Please note the information provided on this page should not be taken as advice and has been written as a matter of opinion. For more on insurance cover and policy wording, see our homepage.