Death, taxes and diesel bug, three of life’s certainties

When editor Hugo’s boat was struck down by a nasty diesel infection, there was only one thing for it – to strip out the tank and have it professionally cleaned

They say there are no certainties in life except death and taxes. If you own an old motor boat for long enough then I’d like to add a third: diesel bug. At some point it’s going to get you, either because you take on bad fuel or you develop your own homegrown infestation in the tank.

I’m pretty sure ours was the latter.

When you own a classic wooden boat like ours, it’s better for the hull to stay in the water all year round, rather than risk the planks drying out over winter and leaking like a sieve when you relaunch it in the spring.

The downside of this is that Isabel spends a long, cold winter safely tucked up in Salterns marina but sitting largely unused for five months of the year – the perfect conditions for the bug to take hold.

Diesel bug debris

The only answer was to clean the whole system

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Until recently, we’ve always taken the view that it’s better to brim the tank at the end of the season and dose it with anti-bacterial treatment to prevent condensation forming on the inside of a half empty tank (the bug grows on the interface between water and diesel).

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However, as most diesel now contains 7% biofuel, that attracts water, there’s a school of thought that says we might be better off leaving it empty.

Who knows whether that would have made any difference but the bug got us towards the end of last summer.

One minute, Isabel was pootling around Poole Harbour with a deckful of assorted relatives, as she has done for the past 70 years since my grandfather bought her. The next, she was spluttering and coughing like a 60-a-day smoker.

An emergency call to the mechanics at the neighbouring Royal Motor Yacht club soon revealed the problem: a fuel filter oozing with the gloopy remains of billions of microbes. A change of filter, fresh fuel and a shock dose of treatment managed to get us through to the end of the season but with winter looming, any remaining pockets would have had another five months to bloom again.

clogged fuel filter

Isabel’s fuel filters were clogged with diesel bug

The only answer was to strip out the fuel tank, clean the whole system and start afresh in the New Year. Thankfully, it’s a fairly small and easily accessible stainless steel tank, which Golden Arrow Marine was able to remove, clean and replace with fresh filters and a new tap for a reasonable £579 inc VAT.

It seems to have done the trick and given that it’s the first time Isabel has been struck by the bug since I’ve been looking after her, I reckon we’ve got away pretty lightly.

Guess that just leaves death and taxes to worry about now!


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