Heading up the River Rance in Brittany, France, we went slowly in our twin-engined motorboat.

The Rance is a locked river used for hydroelectric generation, and its tides are controlled by the need for electricity and are published in advance.

So because it can get shallow we were cautious, following the port hand markers on a rising tide for our trip to Dinand.

All of a sudden, there was a bump, and the boat stopped; I slid forward on my seat, and the port engine stalled.

We’d hit the side of the channel!

Although Gilbert followed the markers, the channel goes way off to port, towards the beach and his boat ran aground. He wasn’t alone – the yacht pictured is anchored after also running aground. Credit: Gilbert Park

Although we’d followed the channel markers between the red buoy we’d just passed and the next red, the channel actually took a big loop between them.

I restarted the port engine and tried all the techniques for getting off – reverse, my wife Máire moving to the bow, the stern, heeling the boat to the side… nothing worked.

As we were on a rising tide, we decided to have lunch and wait. High tide arrived, and if anything, the water seemed lower, and there was a clear bump where the boat had stopped.

I tried to get the boat off again with no luck.

Then, to add to my woes, the exhaust temperature alarm on the port side exhaust alarm went off, so I stopped the engines.

Time to think about what to do next.

There was no option – strip down to my boxers (not a pretty sight) into the water.

Anchor out and pull resulted in no movement. So time to push.

Exhaust temperature alarm that warned of a blocked water inlet to the engine after running aground. Credit: Gilbert Park

Slight movement was detected, then a bit more pushing and the boat moved a little more and a little more; finally, it seemed we might be able to get off. I climbed back on board and started both engines.

No alarms were heard, and the exhaust temperature was normal so off we went, very slowly.

I thought the previous alarm might be because the engine intake was buried in the mud, so water couldn’t get in.

My wife wiped some of the mud off me and gave me a towel to stand on, so the blood from my cut foot (from either a stone or an oyster shell) wouldn’t get on the carpet.

I put on some clothes as we went through the lock, before arriving at Dinard.

Once moored, a long, hot shower helped with my resuscitation and cleaning the mud off, and a plaster on my foot stopped the torrential (man) haemorrhage.

Clean clothes and it was time to look at the boat.

The port water filter was jammed full of horrible, sticky grey mud that needed to be scooped out into a bucket before the filter basket could be removed and cleaned.

On checking the raw water filters, Gilbert found the one for the port engine completely full of mud. The starboard one had a little mud in it, but still functioned normally. Credit: Gilbert Park

Then, the short pipe to the stopcock was washed out using a hose to ensure it was clear.

The engine was restarted, and water came out of the exhaust.

On the return trip down the Rance, the engine had a brief spell at wide open throttle, and the exhaust temperature was normal, so everything was working normally.

On the way down the Rance, we passed where we’d run aground, and there was another boat at exactly the same spot, obviously aground and anchored.

Presumably, the owner had left it aground, intending to return later, so we were not alone in misinterpreting the route and running aground.

That could have been the end of the story, but unfortunately, it wasn’t.

Gearbox oil was black and took two changes in oil before it was a more normal colour. Credit: Gilbert Park

On the way home, we stopped off in Alderney, and in preparation for crossing the Channel, I checked everything, including the oil level in both gearboxes.

Another bit of bad luck. On the port side, the dipstick sheared off when I tried to screw it in.

I secured it with gaffer tape, leaving a space for the vent in the dipstick to work to be able to get home.

Later, having bought a replacement dipstick, I had to get the threaded part out.

More bad luck. I used a screw extractor but it cut a thread all the way through the dipstick, being as it was made of plastic. A larger extractor had the same result.

Eventually, I removed the remaining part with the tang of a file wedged in it.

However, there was a lot of swarf, and I was unsure if any of it had gone into the gearbox.

Before using the boat again, I decided to change the oil and remove any swarf.

On sucking the oil out I found it was black, presumably clutch material, and I assume that it was caused by running aground.

The starboard gearbox oil was its usual clear straw colour. After changing the oil twice, it was clear.

Finally, some good luck: checking the impeller showed it had not been damaged.

Since then, both the engine and the gearbox have performed faultlessly.

Lessons learned

• Going straight between channel markers may be the wrong thing to do, as the channel may move away from a straight line without being marked. At night, be aware that if you’re following a set of channel markers on a corner, they may not all be lit and going between lit ones means you may go outside of the channel. Use radar and the like to follow them.
• If you run aground try all the measures you know to get off. If you do use the engines in reverse don’t overdo it as you may damage the engine and/or gearbox.
• Check the engine water inlet filter for mud, sand or other debris, both during the grounding and once you’re off.
• Fit an exhaust temperature alarm. My exhaust alarm went off at 75°C, well before any damage was done. The same would be true if you forgot to switch on the seacock or the impeller broke up. The cost of fitting one is easily saved if it warns you early.
• Have a pair of shoes or boots to wear if you do go over the side, to protect your feet from sharp stones or oyster shells.
• Don’t overtighten plastic dipsticks that screw in.

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Gilbert Park installs a temperature monitor and alarm to prevent costly exhaust hose damage in the event of impeller failure

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