Leading marine fuel company, Conidia Bioscience, has given some helpful tips and insight into preparing a yacht’s fuel system for winter, and reducing the risk of ‘diesel bug’.
Preparing for the winter layup is traditionally a time to review on-board systems and make an effort to reduce the snagging list. The changes to allowable fuel specification within the Emission Control Areas (ECAs), which come into force in January 2015, should allow more focus to yacht fuel systems. For example, “what are we burning?”, “Are we happy with our on-board fuel management?” and “how clean is our fuel system?”
What fuel is being burned?
The fuel on-board marine crafts should have a flash point of no lower than 60°C i.e. the lowest temperature at which fuel can vaporise to form an ignitable mixture in air. Otherwise, it could be in contravention of The Safety of Life at Sea (SOLAS) directive of the IMO, and could possibly put insurance validations into question.
If yachts have specified and bunkered MGO, then yachts should be in the clear, but many places around the Mediterranean supply road diesel with a lower flash point of 55°C to yachts without informing the recipients. To avoid this problem the correct specification of fuel should be ordered, and a properly completed Bunker Delivery Note (BDN) supplied, which should be retained for three years. Sampling during delivery is also recommended with one sample being sent for testing and the other retained on board for a year.
Are yachts happy with their on-board fuel management?
While the specification of the fuel that’s burned has been changing with environmental legislation, yacht fuel system design has changed little over this time. It may be time to look at our on-board water separation and fuel filtration systems to augment what the manufacturer installed.
Particulate matter can be anything from microbial contamination to rust and general environmental debris. Even small particulate matter can cause serious damage to modern common rail high-pressure fuel systems where the injector tolerances are very fine. Many engine final filters are in the order of five microns, in filter speak, a filter that is marked five microns has “some capability” to capture particles as small as five microns.
No filter, however, will be 100% effective, and a five-micron filter with 95% efficiency will allow particles of greater size than five micron through in one pass. One pass is, of course, all the fuel gets through a single filter on its way to the fuel pump so fitting extra in line filtration between the tank and the engine final filter is well worth consideration.
Whilst fitting additional filters, consideration could be given to installing parallel filters with a changeover facility to enable emergency filter changing while running. Accelerated engine wear due to particulate scoring of injector bores may not have any immediate dire operating consequences. However, the longer-term damage caused by incorrect or irregular combustion distorting the loads on the cylinder head during the power stroke will reduce engine life and increase fuel consumption.
How clean are fuel systems?
Even clean, on-specification, diesel can leave deposits within the fuel system, varnishes and gum can build up in the tank and fuel lines. When any element of Bio fuel is first used, it tends to do a pretty good job at cleaning out the pipes. Many experts advise more frequent filter changes during the changeover from 100% mineral diesel to a biofuel blend due to this “cleansing” process dislodging many years’ worth of deposit build-up.
Biofuel does have another characteristic in that, while all diesel fuels are hygroscopic, biodiesels are even more so. This means that, where possible, regular water draining of the tank bottom is advisable. This is often difficult or impossible with many marine instillations which can lead to the build-up of microbial growth at the water/fuel interface within the tank. Fuel systems are a perfect habitat for micro-organisms to live and grow in, which is why it is so crucial, for sensible husbandry and regular draining to prevent build up, of sediments.
Microbial contamination of fuel, commonly known as the ‘diesel bug’, is an increasing problem with in the marine sector. These harmful micro-organisms, if undetected, can cause blocked fuel filters, wear injectors and stop engines. If they are left for long periods, without treatment the ‘bugs’, can literally eat through stainless steel.
Some manufactures recommend complete fuel tank drain and cleaning on a periodic basis. There are a number of proprietary tests on the market to determine the presence of microbial contamination and prior to the winter layup is a sensible time to consider this option.
Regular fuel testing is the only way we can identify a microbial problem- Conidia’s fuel test FUELSTAT® resinae plus, will deliver accurate results in 10 minutes. FUELSTAT® is the most simple to use test available, using the same technology as a pregnancy test. No special skills are required to use the test, and there is no investment needed for a reader to translate the results.
Completely filling the fuel tank for the winter layup is another well-proven method of reducing condensation inside the tank.
For more information, visit Conidia Bioscience.