I've got a 1986 Westerbeke
27 in my Nonsuch 30, and over the last few years I've used biodiesel in various concentrations from zero to 100%. Here's what I've found:
First, let's make sure we're talking about the same thing. There are a number of folks here who seem to confuse biodiesel and straight vegetable oil
(SVO). SVO is just what it sounds like: used (or new, but rarely) vegetable oil
. It has a very high viscosity and almost always requires installation
of a pre-heater in the fuel line to prevent gelling. I'm guessing this isn't what you're talking about.
Biodiesel is transersterified vegetable oil. It is much closer in viscosity to petrodiesel and can be burned in an unmodified diesel engine. There are a number of biodiesel distrubutors througout the United States. I'm assuming this is what you're talking about.
I've found that mainly the issues you face using biodiesel in a sailboat auxillary are exactly the same issues you face using petrodiesel: filters and water
. Depending on where you live, availability might also be an issue.
When I started using biodiesel I replaced my fuel lines and changed all my filters. All that stuff is/was 20 years old and needed replacing anyway. The only place left with natural rubber is in the lift
pump, and I haven't had any problems. If it quits, I'll get a new one and it'll come with viton seals
I did notice increased crap in the primary (racor 500) when I started using biodiesel, but not much. Probably this is because my tank is pretty clean and the lines were new. It certainly never got to be enough to cause a problem.
The main problem I've found is using a mix of bio-d and petro-d seems to result in some white spooge in the bottom of the filter bowl. I'm not sure what this stuff is, but it's much worse in winter, so I think it might be some sort of water/glycerine/petrolium byproduct. Either that, or the algae is a different color (and there's a lot more of it). I don't get it in summer at all. I also don't get it when I run either straight biodiesel or straight petrodiesel. At any rate, it's a pretty slow accumulation, and cleaning
the bowl when changing the filter (twice a year) keeps it from becoming a problem.
The only real measurable benefit I've noticed to using biodiesel is less soot in the exhaust
. Because of the location of the factory exhaust
on a Nonsuch, they're notorious for having an exhaust stain on the transom. Running a biodiesel mix has greatly reduced this for me. Obviously, the smell is also much nicer. Claims about increased lubricity leading to longer life don't really apply to our engines, since sailboat auxillaries tend to fail from causes other than wearing out their bearings, cams, rings, etc.
I haven't noticed any operational differences between using petrodiesel, biodiesel, or a blend. The temp is the same, RPMs are the same, and it starts fine on either.
I hear an awful lot of apocryphal information about biodiesel, but very little of it is based on first-hand experience. My experience has been that very few of these concerns are warranted.
Hope that helps.