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Engine maintenance

Find out what it's really like to take part in a boat engine maintenance course when you think you don't know much about engines.

Learning to maintain a boat engine

Despite having lived aboard and boated for quite a few years I've never really got to grips with the engine on our narrowboat beyond topping up with water, anti-freeze, fuel and oil. I'm also terrified of electrics and potentially receiving an electric shock. But when you are a boater you do really have to be a bit more practical. To help me conquer my fears I booked a two-day basic boat engine and electrics course with a well-known marine rescue company.

I drove to Stafford very early in the morning for the first day of the course arriving only just in time for the start. Feeling embarrassed at being the last to arrive, I felt even worse when I realised that there was only one other woman on the course and she was attending the course with her husband, and that most of the people on the course were from one single boat club, and that the vast majority were cabin cruisers owners, from fairly modest boats to a monster with twin 470bhp engines!

By chance the only other narrowboat owner was sitting next to me and everyone was kind enough not to mention "sewer tubes" vs "yoghurt pots"!

Engineering mysteries revealed

I needn't have been so worried. The course tutors soon put everyone at ease and we commenced the first theory session on the importance of clean and free air flow, clean oil, clean fuel and the importance of a clean engine and bilges. Various engine parts were passed around the classroom; air, fuel and oil filters and even an array of tappets. I now know what tappets are, what they do, how to check and adjust their clearances and even what they sound like when they've gone wrong! The mysteries of engineering were steadily being revealed.

After a much needed break for coffee we had our first visit to the workshop once most of the class had put their overalls on. I'd got my mucky boat painting come grubby gardening trousers plus safety boots. Overalls are not necessarily required if you don't mind getting a little bit dirty, and to be honest, I hardly got dirty at all.

The workshop had three different diesel engines including a BMC 1.5 which isn't too dissimilar to my own boat's Mitsubushi Thornycroft engine. We were all put to work tracing through air, fuel and oil and systems and then we had a chance to get our hands dirty changing different types of filters and doing an oil change. I discovered that an oil change can be very tiring when you're pumping the oil out by hand and I learnt how to use a strap spanner.

Essential skills

After lunch we had another brief session in the classroom where I discovered the amazingly clever diesel injection system, how on earth did Herr Diesel ever work that out, let alone engineer the first injector? We then had another chance to play in the workshop learning how to bleed the fuel system. This is an essential skill for all boaters as you'll need to be able do this if you ever run out of fuel. Another really useful practical session included fault finding and repairing/adjusting Morse controllers and cables.

The only times I've ever called a boat service engineer out were for running out of fuel (yes, I am suitably embarrassed) and a snapped gear cable. I now feel confident I can deal with both myself. It might be a little bit fiddly and occasionally messy but neither are a terribly difficult or technical task and something all boaters should be able to do.

End of the first day

The first day finished with gearboxes, drive plates, couplings and repacking a stern gland. I particularly liked the stern gland model which allowed you to fiddle about pulling the packing out and putting in back in again. Ignoramus that I was, I had never realised that the packing is in fact rope, mainly because it's a job that I've never done. I also didn't realise that it is possible to replace the stern packing without dry docking the boat. If you are properly prepared you shouldn't sink!

Loads learnt and more to learn on day two. I really did begin to feel that it wasn't as complicated as I'd originally thought.

Day two

The second morning saw us getting to grips with cooling systems, from thermostats to water pumps and more. There are differences between keel cooled/dry exhaust systems and raw water and/or wet exhaust systems. The latter would have been a bit confusing to start with if I hadn't had a bit of experience of a fresh water cooled Perkins engine in a day launch. Fortunately, once again there were lots of parts for us to examine and put together or pull apart, and despite the different systems the principles of how they work are exactly the same.

Finishing off the cooling systems we got to change the fan belts that drive the alternators as well as the water pumps on most engines. After a bit of practice, I finally learnt how to use a ratchet spanner correctly and how far to tighten nuts and adjust belts to the correct tension. Now all I've got to do is learn how to do it dangling upside down, head first into my engine bay from my cruiser deck!

Electrics aren't shocking

The final part of the course covered boat electrics, both the theory and the practical. I was worried about this part of the course, firstly because I was scared of giving myself an electric shock and secondly because maths is not my strongest subject. I needn't have worried. Twelve volt systems aren't like 240 volt systems although they do still need to be treated with respect. And the maths doesn't have to be that difficult unless you want it to be difficult, in which case you'd probably want to get advice from a fully qualified boat electrician.

Making sense of a wiring loom

The final practical session got us using a Multimeter to do voltage drop and continuity checking across the entire wiring loom of the engines in the workshop. It really helped me to think of the batteries like a fuel tank and the wires coming from them like fuel lines. After what seemed like no time at all we were confidently locating and fixing a number of electrical faults. I even stripped back my first wire, crimped on a new connector and reconnected a faulty oil pressure sensor back to the control panel.

Time well spent

By the end of the course I really felt that I'd learnt loads, in fact I wish I'd done it years ago and not been scared of something that on the face of it seemed to be rather technical and complicated. The basic engineering principles that make an engine work aren't difficult and it really helped having training engines that were easily accessible for us to make our first attempts at servicing and repairs. Engines really are for everyone! I'm now looking forward to servicing my own engine despite the challenge of working in the confined space of my narrowboat engine hole. At least I should have more than half a clue where each part should be located.

Top Tips

  • Carry a tool box on board, at the very least you'll need a couple of adjustable spanners, some screwdrivers with an assortment of different heads and a multimeter. Rachet spanners are very handy as are socket sets.
  • Carry some spares, always have a spare fan belt, some fuses, filters and a teleflex cable in case your gear or throttle cable snap.
  • At the very least, learn how to bleed your engine. Should you be unfortunate enough to run out of fuel at least you''ll be able to get going again once you've filled up.
  • If you don't feel confident about the contents of your engine bay, what the various parts do and where to find them, take a course. It's really helped me.

Last Edited: 25 October 2022

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