No Alcohol please, we’re Diving !

Nov 06 2014 Posted by Office Administraton

WS Rust 1

The corrosion effects of ethanol during winter storage on typical water separator.

Cloudy Fuel

Fuel removed from a new 25 micron water separator after 6 weeks, (note the cloudy appearance).


An example of a small spare fuel tank for cleaning a boat engine with Aspen.






As divers we are fully aware that alcohol and diving don’t mix but some of you may not be aware of how much alcohol is consumed by the average dive boat in recent years. Now before you jump to any conclusions it is your boats engine that’s consuming the alcohol while transporting divers. This is the alcohol that is causing concern to boat users and owners worldwide and many people aren’t aware of its devastating effects.

Article submitted, by Peter Walsh, Limerick SubAqua Club

We are talking about ethyl alcohol or “Ethanol” and at present fuel can contain levels ranging from 5-10% and possibly more. In the last 3 years more and more alcohol has been blended into automotive fuel which is specifically suited to the modern petrol car engine. If you purchase your fuel from any filling station in Ireland the chances are it will contain at least 4% ethanol unless stated otherwise. It has now been established that ethanol is causing major problems to small garden equipment engines like chainsaws, lawn mowers, strimmer’s and of course boat engines.

The reason for this is because all of the above spend many weeks if not months idle and are usually stored for long periods over the winter. As a member of Limerick Sub Aqua Club I have observed very expensive engine repair bills in recent years and it’s quite possible that ethanol may have had a part in at least some of those repairs. There are 2 main reasons why petroleum companies have introduced ethanol into fuel 1. Environmental: It was supposed to clean the fuel 2. Supply: World supply is down and demand is up. The environmental impact of introducing ethanol into fuel is still up for debate especially with regard to world food shortages and the huge carbon footprint to actually produce it.

For the purpose of this article I am going to stick with the main issue and that is the damage that it can cause to expensive boat engines and associated equipment. Initially ethanol was introduced into fuel at 5% (E5) but that has now risen to 10% (E10) and in the USA 15% ethanol (E15) is now available at gas stations. Do we know what percentage we are actually getting or are we at the mercy of the fuel companies. E15 is really only suitable for the very modern car (2012 onwards) but can be catastrophic in boat engines. While E10 can be tolerated well by modern boat engines the problem arises when boats are left idle for long periods with ethanol remaining in the fuel system. Some dive boats can be idle for several weeks due to bad weather and in winter this can stretch to several months. Many of the main marine engine manufacturers now clearly state that their warranty will not cover any fuel related engine damage.

We could learn some lessons in fuel management from our friends with light aircraft in Flying Clubs across the country. Apparently ethanol in aircraft fuel can lead to catastrophic engine failure at altitude so flying club members rigorously check their petrol for traces of ethanol with special “Test Kits”. Trying to locate alcohol free fuel nowadays is becoming more and more difficult as it often government policy that fuel must contain at minimum percentage of ethanol.
Stagnant ethanol has negative effects on all the various components that it comes in contact with. Petrol tanks, fuel filters, water separators, fuel pumps, carburettors and injectors. The rubber components perish and the metal components corrode or rust (Figure 1 and 2). Alcohol blended fuels will absorb moisture from the air but once the water content of the fuel has built up to approximately a half of 1 percent it will separate out in a process called “ phase separation “. The water will then draw the alcohol from the fuel and both of these are heavier than the fuel so they settle in the bottom of the fuel tank.

Traditionally water separators and fuel filters did a good job of removing water but alcohol in fuel acts like a solvent and can quickly corrode and perish the inside of the filter rendering it ineffective. Water separators “do exactly what it says on the tin”, that is, they separate water, but they may not prevent ethanol from reaching the combustion chambers of the engine. Many water separators for alcohol free unleaded fuel come with a 25 micron rating (Fig.3) and this was adequate for most applications in the past but the arrival of ethanol has necessitated a higher spec/grade of filter such as a 10 micron rating. (25 micron rating removes 75% of water and 10 micron rating removes 90% of water) Make sure your boat is equipped with 10 micron water separator(s) for better protection.
Recently I have discovered a new product which I believe will give maximum protection for boat engines and quite frankly it is a lifeline to a boat owner in combating the ethanol issue. The product is called “Aspen Alkylate Petrol”(Fig.4). Originally developed for the lumbar (chainsaw) industry to reduce toxic fume inhalation by workers, it not only has health benefits for the user but it also keeps the engine in a healthy state. It comes in 5Litre canisters, Aspen 2 for 2 Stroke engines and Aspen 4 for 4 Stroke engines. It has a high octane rating, contains no solvents (ethanol) and is environmentally friendly. I have tested this product and it has many benefits which I believe will extend the lifespan of any marine engine.
In the past marine engine manufacturers recommended “Fogging” a boat engine as part of the winterizing procedure. Fogging is a method where oil was sprayed into the pistons and combustion chambers while the engine was running literally choking the engine with oil until it cuts out. Although helpful for preventing rust and corrosion from long periods of non-use the arrival of ethanol has caused a re-think of winterizing methods for boat engines. The latest trend is to run the engine in a tank, barrel or fresh water regularly throughout the winter thereby eliminating the need for idle storage. The procedure can be performed every 2-3 weeks to be effective and this is where the use of a product like “Aspen” can really bring significant benefits. I will now describe a method on how Aspen can be used both during winter and throughout the dive season to prevent unnecessary engine and fuel system damage.

Whether your club has a fixed/built-in petrol tank or portable tanks the use of an additional ethanol-free portable tank is a must. A small container can be modified for this purpose (Fig. 4) or a small 5-6 litre fuel tank can be purchased. Coupled with this you will need a separate fuel line with a priming bulb and the appropriate connectors for the tank and the engine. This fuel line and tank can either be attached to the engine directly or to the water separator housing at the end of a dive trip. Then the Aspen is allowed to run through the engine for 5-10 minutes either before the boat is recovered from the water or else when the boat is returned to its storage location with the aid of a water tank or flushing device. This procedure if performed regularly will ensure that no ethanol residue will remain inside the engine during storage. This can also be performed regularly throughout the winter to keep the engines moving parts lubricated. Ideally the whole fuel system would benefit from running Aspen from tank to engine, but this may be difficult with fixed tanks.

It may not be practical or possible to empty the main fuel tank and run Aspen through it but the engine is our main concern as fuel lines can be replaced much easier and cheaper than an engine. It is well worth siphoning off all the fuel from the main tank before winter storage and using small amounts of Aspen to run the engine during this period.
I would encourage all coxswains and equipment officers to research the corrosive effects of ethanol and there is plenty of advice and information online with regard to the marine implications. It could save your club thousands in unnecessary and expensive engine repairs which very often are not visible during routine servicing and maintenance.
Acknowledgements /Sources:
• My club mate Noel Hickey for his help in help with sourcing products
• Barry at Mower Power, Limerick for supplying product information on Aspen
• YouTube for educating me on all aspects of the “Ethanol Debate”
• Honda, Mercury and Yamaha online owner’s manuals for warranty related information.
• Dave Ryan and Dave Keane for their tools, equipment, advice and help.
• For comments, suggestions or any other interesting information regarding this topic please contact me at