Boat Engines vs Truck Engines

Boat Engines vs Truck Engines

marine engine install

Here’s why a boat can’t achieve the fuel efficiency and longevity of the truck that tows it.

Today’s marine engines are high-tech wonders. Flush them and change the oil at regular intervals, and you should expect hundreds of hours of faithful service. Yet we still often hear casual boaters wondering why a boat can’t achieve the fuel efficiency and longevity of the truck that tows it, especially since they share the same engine block. Here’s why.

Multiple Gears

An automotive engine kicks down to a lower rpm at top speeds. In contrast, a marine engine's sustained speed only increases with sustained rpm. Basically, a truck motor has four to six gears, and a marine motor has one.
It only makes matters worse when a boat engine isn't properly broken in.

Frequency of Use

A car engine has an advantage in that it gets run every day, and engineers say hours are good. Think of it in terms of physics. Things in motion stay in motion. An object at rest tends to rust — from the inside out.


A car typically runs on a dry road, has plenty of ventilation and is better regulated in temperature thanks to closed cooling systems (like a radiator). In contrast, a boat is always operating in a moist, corrosive environment and is typically cooled by the surrounding waters — and then there's the shakedown from high seas.
The motor essentially takes a steam bath, if not a beating, every time out.


Bottom line: Marine mechanics tell me most of the problems they see are primarily due to user neglect. These include the use of cheap lubricants, improper break-in, overpropping, etc.
The engine doesn't suddenly decide it's tired and done. Something led up to it.

Article courtesy of Jeff Hemmel. The contents of this article are for informational purposes only and are not intended for diagnosing. Boating Basics does not guarantee - expressed or implied - any specific results and a professional should be consulted on more serious issues.

We hope this article has helped to explain many of the various differences between boat engines and truck engines as well as the importance of knowing those differences. At the end of the day it comes down to the best engine for the job at hand. And that means using a marine specific engine to power your boat.