Narrowboat Engine Field Report
Half the BMC Starters on the Cut Are Held On by Two Bolts Out of Three. Mine Was One of Them for Twenty Years.
June 2026 · 9 min read
Twelve years aboard Maureen. I do my own engine work, because out here the engineer is always three weeks away.
There is a bolt on the most common old engine on the English canals that the whole cut quietly agreed, somewhere around 1975, to stop fitting. Not because it is not needed. Because nobody can get a spanner on it. If you run a BMC 1.5, lift your deck boards and count the bolts on your starter motor. There should be three. I will wait.
I am not a mechanic and I am not selling anything. I am a retired railway signalman, and for twelve years my wife Sue and I have lived aboard Maureen, a 57 foot boat with a BMC 1.5 in the engine 'ole, working the Grand Union and whatever water takes our fancy. I do my own engine work, partly because I like it, and mostly because out here the engineer is booked for weeks, and the boat is not just the boat. It is the house.
I am writing this for every boater who has lain head first down their engine 'ole with one arm wedged past the bearer, working a fastener by feel, while the daylight went. Because an old engineer who moors three boats down from us handed me the answer, and he told me to pass it on.
The bolt the whole canal agreed to forget
Here is the part nobody puts in the boating magazines. The BMC 1.5 is a fine old engine, simple and strong, and it was designed on a bench in the Midlands where every fastener sat out in the open. Then the boatbuilders lowered it into a steel hull, into a hole the size of a kitchen cupboard under the stern deck, jammed against the bearers, and the starter motor ended up low on the side of the block where one of its three mounting bolts faces nothing but cold steel plate, two inches away.
Do not take my word for what happened next. The men who know these engines best say it plainly on the owners' forums: getting a spanner onto that one bolt was so awkward that generations of three-bolt starters have simply been fitted with two. That is not a shortcut one lazy chap took once. That is the whole cut, surrendering to one fastener, for fifty years. And a diesel shakes. Two bolts work loose where three would not. Which is how my starter ended up clicking instead of cranking, at eight in the morning, on a water point, with boats queuing behind us.
Everything I tried, down the 'ole, head first
- Standard ratchet. There is no swing between the starter and the hull side. It clicked once and stopped dead against the plate.
- Flex-head ratchet. Reached the bolt, then folded at its joint the moment I leaned on it. My knuckles found the engine bearer, which is steel, and does not give.
- Socket on a long extension. Could not come in straight past the bearer, tipped under load, and started chewing the corners off a bolt that last moved when this boat was painted.
- Working by feel, lying on the deck boards, one arm down beside a warm engine. Twenty minutes a session, because that is what a shoulder lasts at sixty-seven.
- The engineer. Sixty to ninety pounds an hour out here, booked solid for weeks. And if you are stranded without breakdown cover, joining River Canal Rescue on the day costs one hundred and seventy pounds before a man so much as lifts your boards.
What being stuck actually costs on the cut
Put the numbers on the table. Proper breakdown cover for a boat runs to three hundred and sixty five pounds a year. Go without it, break down somewhere pretty, and joining on the day costs one hundred and seventy pounds, not refundable, before anyone touches a spanner, and thirty more inside the M25. The mobile engineers are good men and there are not enough of them; the ones worth having are booked for weeks, and there is a whole thread on the boating forums that is nothing but owners trading stories about tradesmen who never turned up. And while you wait, you are not waiting at home. You ARE home. Tied to a ring on a towpath, four miles an hour from anywhere, with the fridge slowly warming and your wife being very patient about it.
That morning on the water point, with the starter clicking and a queue forming, Sue made tea and did not say anything. Twelve years aboard and she knows the difference between a man who wants company and a man who wants a minute. I sat on the stern and did the sums on what this little bolt was about to cost us, and the sums had nothing to do with why I could not look at her.
Down the 'ole, head first, one arm, by feel. Every boater on the cut knows this position.
Then the old engineer three boats down handed me a bar
Reg is seventy-eight. He spent forty years as a mobile engineer on these canals, out of a van first and a butty later, and the boaters of three counties learned to flag him down like a bus. He heard my starter clicking that morning, walked up the towpath with his mug, and listened to the whole story. The two bolts. The third one I could touch with a fingertip and could not turn. The clicking. He did not laugh. He went back to his boat and came up out of his engine 'ole with a flat steel bar, about the length of his forearm, with a square drive at each end.
He had me press the drive end with my thumb. Something gave, very slightly, inside the steel. A roller chain, sealed along the length of the bar. "The chain carries the turn round the bend," he said. "You feed the bar in flat past the bearer, where there is room, your socket sits square on the bolt at the far end, and the pull lands dead flat. It cannot fold, there is no hinge in it. It cannot walk off, the drive never lifts. I made mine in the eighties because every boat on this cut had the same three jobs nobody could reach. Somebody finally builds a proper one. Buy the real article, mind. The copies fold."
"The chain takes the bend for you."
A slim, dead straight bar, about half an inch thick, that slides flat into the gap between the engine and the hull where nothing else fits. The sealed roller chain inside carries your pull round the offset and lands it square on the fastener. It is called the Savary offset wrench, and it is the bar Reg spent forty years making by hand for the boats on his round.
The sealed chain is the trick
A roller chain inside the steel body carries torque round the bend, so it never folds like a flex-head or walks like a universal joint.
Slides into the gap
A slim half inch thick bar slips down between the block and the hull side where no ratchet can swing.
Takes your own sockets
Square drive at both ends fits the sockets already aboard. Holds real torque, up to seventy newton metres, a shade past fifty foot pounds.
It reaches. It is honest.
This solves access to a fastener you cannot get a tool on. It is the right shape for an engine 'ole, not a miracle for a bolt rusted to nothing.
It only comes from one place
You will not find it at the chandlery and you will not find it at the boat jumble. The maker sells direct from their own site only. Sixty nine pounds, shipped tracked to your door, or to a marina office if you are on the move. That is less than half of one call-out, and a small fraction of joining the rescue people on the day, for the one tool that turns the job the whole cut gave up on into a quiet morning at your mooring with the kettle on.
What happened next
Other boaters who stopped surrendering to it
"Fitted the third starter bolt for the first time in eighteen years of owning this boat. Took twenty minutes at the mooring. I had genuinely accepted it could not be done."
"Engine mount nuts under the alternator, the ones the yard wanted the engine lifted for. Did them from above with this bar, boat in the water, kettle on."
"Bought a cheap chain bar off eBay first. It folded on the first proper pull, exactly as the man warned. The real one does not give a millimetre. Chalk and cheese."
Reg made his own in the eighties because every boat on his round had the same jobs nobody could reach. Now there is a proper one, and he is passing it on.
Get yours before the cruising season runs out
If there is a BMC, a Lister, a Beta or any diesel down your engine 'ole, and one fastener on it that the previous owner quietly gave up on, you already know exactly what this is worth. And if you have been telling yourself you are getting too old to go down that hole, it was never your hands. It was the shape of the tools.
The Towpath Field Notes is a reader-supported publication. This is a first-person account from a private boat owner and reflects his personal experience. The Savary offset extension wrench is a hand tool designed to reach fasteners in tight, blind locations. It improves access; it is not represented as a remedy for fasteners that are corroded or seized beyond normal service. Always follow proper service procedures and torque specifications. Results vary by vessel and condition. This publication is not affiliated with River Canal Rescue or the Canal & River Trust.
