Biodiesel fuel.

I would venture to say the last thing you would want to do is introduce a fuel chemistry that was developed after the design of your 2-cycle diesel and then force feed it, so to speak.

Would not recommend it.

The big issue with running biodiesel is that it runs super clean, and will scrub the entire fuel system clean. You will go through plenty of filters! The second is that all natural rubber hose in the system need to be replaced, as the solvent properties of the fuel will degrade the lines. The fuel will run fine in the engines, but you have to be prepared for it .

An on-highway fleet operation of Biodiesel is a good application - the trucks don't sit around and you are continually refueling.

The use of Biodiesel in a recreational vessel is a different story, including the fact that the natural components in the fuel mixture will age and cause issues down the line. Even if you are running 1000 hours per year, you are not cycling the product enough to prevent aging issues from occurring. Gumming up your fuel system, leaving deposits and creating unsuspected wear on fuel system components. The use of additives is also needed to manage the biodiesel aging in your tanks.

You have to have a reliable supplier as there are many different grades - B5, B20, B30 and others, each with their own quarks. Fuel Filter change intervals increase, Lube Oil/Filter change intervals cut in half, some recommend flushing your entire engine /fuel system with non-biodiesel annually as well.

Have a hard time seeing a recreational boater pull off the extra vigilance needed with this type of fuel, not too mention the drop in power that these fuels produce - about a 2 - 3% reduction.

Better off being used in a fleet like a ferry which has a specific run and doesn't carry a lot of extra fuel storage.

Which biodiesel?

B15 is a completely different animal than WVO. Your Detroit will run both, and anything in between, but the tradeoffs vary greatly.

Generally speaking, if you own some fast food restaurants (or Americanized "Chinese" restaurants- their oil is the purest) and stay in tropical climates you can save a lot in fuel costs. Outside of that situation it's not cost effective.

I don't know about boats. But I know a diesel and outboard mechanic that has a perfect running Ford powerstroke 1997 7.3 diesel F 250. He runs drain oil in it. He'll literally do an oil change on a yacht and pour 10 gallons of drain oil right into the fuel tank with 1/2 a tank of diesel in there with nothing more than a paint strainer to strain it. It runs quieter and perfect on it and doesn't even smoke. He's been doing this for 7 years and has run 10's of 1000's of gallons of engine drain oil through it with no issues whatsoever, and mixes it like 50/50 with diesel fuel.

Pre-20teens diesels are very tolerant of a wide variety of fuels.

I've seen Chevy 6.2 and 6.5l run on straight Wesson cooking oil no problem, no changes from stock. Not below 50 degrees F though.

The later emissions restricted DEF diesels not so much.

The only big question for Detroits is whether the solvent cleaning of the fuel system (and subsequent filter changes) are worth the effort. If the biodiesel is cheap or free then great. If it isn't then it's not worth the hassle.

Any engine can be converted to burn a new type of fuel. You might have to get the details of the Bio-Diesel you want to use and pass on the details to the engine manufacturer to find out if the engine could burn that fuel in it's stock configuration.