Winter Preparation for your yacht #2 Fuel Systems

Fuel tanks and fuel systems.

During the winter months, this is a good opportunity to have them cleaned thoroughly if you suspect any contamination in the fuel, or if you have an older boat. I would recommend having the fuel pumped out, filtered and put back into a clean tank. This is a fairly easy process, utilising a fairly large pump and clean containers, the fuel is removed, filtered and returned all in one smooth operation. Alternatively, the fuel is pumped out and stored in clean containers whilst the tanks are cleaned. After this the fuel is put back into the tanks, being filtered before doing so. A filtration level of around 100 microns is fine for this procedure.

Seaway Diesel Contamination

Cleaning the tank / tanks. This is slightly more awkward, in that some fuel tanks may not be so easily accessible due to the design / construction of the yacht. Not all designers have maintenance in mind unfortunately! What is required here, is to use a ‘wet vac’ type arrangement, where any residual fuel and dirt / sludge which builds up in the tank is vacuumed away. Reaching all areas of the tank can be very difficult, however being thorough here will mean it will not need doing again for a few years! If the sludge is not thoroughly removed, then this can and will find its way into your engine, after blocking the filters en route! We have experience of this whilst motoring or motor sailing with only moderate chop! The motion of the vessel is enough to stir up the sludge and consequently it is drawn into the fuel lines, causing an expensive problem.







Many tanks have inspection covers large enough to easily accommodate an arm and vacuum tube, others only have a solid stainless tank. Options here would be to cut a hole large enough – around 10″ in the top for inspection. To reseal this, a fuel resistant gasket will be needed to cover this new and suitable fixings put into place.

Being aware and overly cautious of fuel that you put onboard is very important. Murphy’s law will come true when the engine is needed the most!

Fuel additives / diesel bug additive / condition treatment of the fuel is important also. The maintenance of the tank once clean is necessary. We need to keep water away from the insides of the tank as far as possible, which means either completely emptying the tank for the winter, or filling it completely. This will reduce the amount of condensation which will form on the inside of the tank walls and subsequently run into the fuel. Reducing the amount of air in the tank – i.e. by filling the tank completely is advisable. Replacing primary filters on a
regular basis is important, as are the fuel filters on the engine itself. 

Clean fuel will prolong the life of the engine and pollute less.