The biodiesel bottom-line- No good for cruising yachties

by Bob Senter on 17 Apr 2010 Regardless of people's personal opinions whether Biodiesel is a good thing or a bad thing, one thing is for sure. It will attack normal gaskets, hoses, o-rings, and possibly synthetic fuel tanks found on many vessels.

This is the official position of Northern Lights, a world leader in marine diesel engines, regarding Bio Diesel as written by Bob Senter, and published here with his permission: (Warning: Bob's view is hotly denied by some biodiesel engineers.)

While biodiesel is certainly appealing in some ways, in its current state of refinement it is totally unsuitable for long range cruisers, sailboats, boats with very large tanks and standby generators.

Here's the short version of why:

1. Biodiesel degrades quickly, like milk. According to Deere, it must be used within 90 days of manufacture, a near impossibility in marine applications and standby generators.

2. Biodiesel's strong solvent-like properties do a great job of cleaning normal accumulations of asphaltenes from tanks and fuel lines; the freshly loosened debris plugs the filters.

3. Most of the flexible hose components, gaskets, seals, diaphragms and O-rings will be gradually softened and/or dissolved by biodiesel. The problem is insidious because the engine will run extremely well until the problems begin.

4. Once the dissolved materials begin to enter the fuel system, fuel injection system failures and upper cylinder failures can occur - these materials were never designed to be burned in the combustion chamber. External leaks and filter plugging are the least of your worries. The longer term fuel system and engine component failures are likely to be much more oppressive and expensive.

Without debating the merits or challenges of biodiesel, I hope that these challenges are overcome in the not too distant future. The reality for now is that it really only works well in some highway vehicles and agriculture/ construction equipment where all the fuel is consumed in a few days.

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This is a letter from Stan Steinberg from Inner Wisdom, received via Cruisers Network Online, of which he is a member. He outlines his practical experience using biodiesel:

I may be the only cruiser with a pair of 14 liter Detroit Diesel engines developing 825 HP each. Nevertheless, most diesel engines will probably react similarly to the use of biodiesel fuel and accordingly the following recommendations from Detroit Diesel may be helpful. I will also maintain my Northern Lights genset according to these recommendations when faced with biodiesel as the only option.

- Engine oil and filters (oil and fuel) must be changed after the first 25 hours of operation using biodiesel due to the danger of blockage caused by loosened deposits.
- Reduce engine oil change to 30% of the interval required for operation with fossil diesel, replacing all oil and fuel filters at each oil change.
- Prior to any extended period out of operation the fuel system must be flushed by running the engine for at least 30 minutes on fossil diesel.

Other interesting information.
- Biodiesel is an extremely effective solvent so contact with painted surfaces should be avoided.
- Biodiesel will deliver 8-10% less power and therefore result in a corresponding increase in fuel consumption.
- A certain amount of fuel always finds its way into the engine oil via pistons and cylinders. Its high boiling point means that biodiesel does not evaporate but remains in the engine oil in its entirety. Under certain conditions chemical reactions may take place between biodiesel and engine oil. This can lead to engine damage.
- Biodiesel may be referred to as 'FAME' (Fatty Acid Methyl Ether.)

Clearly, after arriving at a location with fossil diesel one may choose to remove any remaining biodiesel from onboard tanks or at least flush the engine from a 5 gallon can if removal is not an option
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I respectfully disagree with the conclusions and recommendations contained in the article by Bob Senter.

In response to his four points:

1. Biodiesel degrades quickly, like milk. According to Deere, it must be used within 90 days of manufacture, a near impossibility in
marine applications and standby generators.

Response - Untrue. The new Rancimat test required by the ASTM standard for biodiesel requires stability testing. Research has
shown that additives can extend the shelf life of biodiesel substantially. Just like you would use Biobor (or its equivalent) in
petroleum diesel, there are additives suitable for biodiesel for extended use situation. Most stability problems in petroleum
diesel and biodiesel are cause by microbial growth, water in the fuel, and oxidative and thermal instability. There are additives
and procedures to address all of these problems.

2. Biodiesel's strong solvent-like properties do a great job of cleaning normal accumulations of asphaltenes from tanks and fuel
lines; the freshly loosened debris plugs the filters.

Response. Partially true. Yes, biodiesel is a solvent and will clean out your system. Do you really want all that crud in your
system anyway? If you are going to use biodiesel, start before your cruise, use a 20% blend of biodiesel for several hours, then
have your tanks cleaned, and start with a new set of filters. You will find that your engine will run better with a clean system,
and smoother because of the high cetane rating of biodiesel. If you have a build up of crud, you should get rid of it, otherwise it
could break loose in the turbulence of bad weather.

3. Most of the flexible hose components, gaskets, seals, diaphragms and O-rings will be gradually softened and/or dissolved by
biodiesel. The problem is insidious because the engine will run extremely well until the problems begin.

Response. Untrue. Modern diesel hoses, gaskets, diaphrams and fuel lines are compatible with biodiesel blends. Goodyear makes such
a product and any viton based elastomer will work. It is good to check your hoses and fuel lines prior to a long offshore trip. It
is inexpensive insurance to replace them, and when you do make sure they are made from compounds that are biodiesel compatible.

4. Once the dissolved materials begin to enter the fuel system, fuel injection system failures and upper cylinder failures can
occur - these materials were never designed to be burned in the combustion chamber. External leaks and filter plugging are the least
of your worries. The longer term fuel system and engine component failures are likely to be much more oppressive and expensive.

Response. Untrue. If you follow the procedures outlined above, this will not happen. For further information see
www.biodiesel.org.

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