Some time ago we ran a post on the relative advantages and disadvantages of marine diesel engines vs gas. I realized that when it comes to making that decision, many boaters come in with some preconceived notions about diesel engines, many of which are simply either untrue, or were true long ago, but no longer apply to modern diesel marine engines. So, I thought it was time we “busted,” some of these persistent diesel engine myths.

Myths and Misunderstandings about Diesel Engines

Diesel engines are diehard machines – One of the most popular myths we run across about diesel engines is that “you can run them for thousands of hours with little or no maintenance…” Most yacht owners who believe in this myth have had it “busted” by major repair bills! Like many myths or legends, this one has some basis in reality. Diesel engines earned this reputation as workhorses because of their continuous use in commercial operations such as on long haul trucks, industrial generators and commercial transport ships.

Diesel engine overhaul

Marine Engineer Works on a Diesel Engine

However, the truth is, in those applications, diesel engines only seem to run forever, because they are run constantly. The diesel engines on your yacht will never be run for the number of non-stop hours as they would be on trucks or cargo ships. In fact, it is that constant running that keeps them healthy. Disuse of a diesel engine, and starting and stopping it frequently as you would typically do on a motor yacht, actually shortens its lifespan more, than when they are running constantly in these other applications.

Diesel engines are safer than gasoline engines – This is another persistent myth, that since diesel fuel is somewhat less combustible than gasoline, (diesel vapors are not combustible) they are inherently safer to have on a boat than gasoline engines. While there is some truth to this myth, it should not be the decision-maker on gas vs diesel. While gasoline fumes are explosive and diesel vapors are not, the instances of marine gas engines bursting into flame are actually quite rare, and statistically speaking a gasoline engine does not really present a greater fire risk, than do diesels. Of greater concern is carbon monoxide (CO). Gas exhaust does produce much more CO than diesel, but instances of CO poisoning usually come from a problem with gas generators, and not gasoline engines.

Diesel engines are more economical – Like some long running diesel engines, this myth just refuses to die. There was a time when marine diesel fuel did cost significantly less than gasoline, that is no longer the case. It is true that marine diesel engines may get somewhat better fuel economy than gasoline engines of comparable horsepower. But, they really do not last longer than gasoline engines (see Myth #1), and when they do break down, they are far more expensive to repair than are their gasoline counter parts. So, in the long run, they do not really cost less than gasoline engines.

Keeping Your Engines Healthy

Regardless if your motor yacht has diesel or gasoline engines, planned maintenance is the best way to ensure their safe operation and long life. In either kind of engine, neglect can lead to breakdown and failures, and usually not at the most opportune times!

Preventative maintenance, like you will have as part of our charter income fleet, or if you sign on as a member of On Demand Yachting, will keep your engines healthy and minimize your potential for much bigger and more expensive repairs or overhauls.


Operating a motor yacht can be costly. You can reduce your expenses, and avoid costly repairs by keeping her well maintained. On Demand yachting from FYM can help. If you would like to learn more, or if you have any questions or comments about this blog post, do not hesitate to contact our Yacht Management specialists, or call us at (954) 900-9968.