The problem that bugs all cruising yachts

Dick Beaumont explains how it can be eradicated

Eighty percent of breakdowns and failures on blue water cruising yachts are caused by fuel contamination and the further one wanders off the beaten track the more difficult it becomes to access good quality clean fuel.

I was once sailing, or rather mostly motoring, through Indonesia on passage to Bali and our fuel reserves were getting very low, so we decided to put in to a small Indonesian Island called Pulau Sangkapura in the Java Sea.

This island is very remote and its isolation has regretfully created poverty, rather than beauty. There were no marinas, or even garages and after some translation difficulties we managed to explain, to the hundred or so villagers that had gathered, that we needed diesel, called Solar in Indonesia. This involved several five-mile journeys on mopeds with our jerry cans, back and forth to the shack of the Solar man. 

He proudly pulled the tarpaulins off four open-topped, 500 litre, steel, oil drums. As we began to syphon fuel – he had no pump – from the first one into a jerry can, Toby my crew shouted ‘STOP, STOP.’ He told me he’d seen debris and what looked like water going through the syphon pipe into our jerry can and said ‘Dick we can’t put that s**t in our tanks’. We put a stick in the drum and stirred a little to see leaves, twigs and bits of cockroach swirl round. I told him there was no alternative, it’s this diesel or nothing.

We had to take the diesel but constructed a portable diesel filtering system, which I continued to use successfully for a further seven years as I sailed around SE Asia, and beyond. (see fig 1) 

It was the inspiration for the development of the three tank with fuel polishing and transfer system we now fit on all Krakens as standard, see fig 2.

After this experience we rated all diesel purity as 1 – 9 cockroaches per gallon, the fuel in Pulau Sangkapura was an 8, only surpassed by a Filipino Solar seller who admitted he added water to the diesel. When asked why, he said ‘It goes further’ meaning his sales of diesel, not the engine that was using it!

Fuel contamination can be caused by:

  1. Taking on dirty fuel containing foreign matter

Whilst in an ideal world, you would simply refuse it and go elsewhere there are many places in the world where that isn’t an option as I mentioned above. Many fuel barges and fuel bunkering jetties in the wilder parts of the world will only have poor quality fuel.

2. Allowing water and contaminants into the fuel whilst filling your tanks, i.e. when it starts to rain

Sod’s law, it will start to rain as you fuel up, and whilst you can put an umbrella or sheet over the filler, water, salt and grime wash along the scuppers and on most yachts, with flush deck fillers, the water and all, will go straight into the tanks.

We developed the dual recessed and covered fuel filling station to solve this problem on all Kraken yachts because, once the contamination is in the tank it is a major operation getting it all out again.

Note: both port and starboard are filled from this one position so there’s no need to drag the dirty black fuel hose across your lovely teak decks.

3. Leaving fuel tanks half empty

Water in the humid warm air, condensates on the tank sides, internally, when the tank cools down. 

4. Filling up your tanks!

What many cruisers are not aware of, is that all diesel now contains biodiesel and biodiesel holds and absorbs more than six times more water than petroleum diesel, and water in diesel allows diesel bug to form and grow.

If left in the fuel system diesel bug, which is actually a type of bacterial fungi, will get past your fuel filter and right into your engine fuel system, then even into your engine and generator’s injectors. To say it will shut you down is an understatement, as the whole fuel system will need to be cleaned and flushed through and it’s a horrible job.

To avoid engine and generator shut down you must run them on clean pure diesel and in the Kraken three tank system you cannot under any circumstances fill the running tank directly from the shore, all fuel must go into either the port or starboard storage tanks and fuel from those tanks can only be transferred into the running tank by passing through the fuel polishing system that eliminates all contamination and water. The same can be achieved by using the portable fuel filtration system in fig 1, however, as I have said due to the introduction of biodiesel, and the water it holds, a diesel biocide should still be added every 4 or 5 fills even so.

There are many brands of diesel biocide available. I use Kathon FP1.5 Biocide which is produced by DuPont. It is available in a 5 litre container which, as a preventative, treats 30,000 litres so will last me a good while.

If the running tank isn’t too big, only enough to run for 2 days or so, small volumes of water that do aggregate in the running tank will, due to the yacht’s action, emulsify into the diesel and get burned through the engine, as long as the diesel bug hasn’t had a chance to grow, all will be fine.

White Dragon is now three years old but has already sailed the distance most yachts cover in ten years or more and her tanks, especially the running tank, remains totally clear.

The percentage of biodiesel has been increasing in the diesel we use, so this is a growing problem.

This is the fuel transfer system on White Dragon. Note all Racor filters are in full view. The large filter and water seperator on the right is the the filter for the fuel polishing system through which the port and starboard fuel storage tanks supply the running tank.

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