Engine Hours Marine vs, Auto Service Bulletin 1961

Was talking engine hours today at a wood boat shop and he gave me this interesting cool Chris Craft Service Bulletin dated January 15, 1961. No clue how to scan it onto the site so will just type it here:

Marine Engine Revolutions

Whenever the subject of engine maintenance is discussed, invariably reference is made to an automobile engine for comparison.

One of the main differences in the operating conditions of a marine engine and an automobile engine is that the marine engine is continually under load and is what you might say going up hill all the time. This places a much greater load on the pistons and bearings and increases the internal heat range to a great extent.

It is usually considered that an operating period of 100 hours of a marine engine is equal to 10,000 miles of average automobile driving.

To further illustrate the extent to which the boat engine is severely punished, refer to the chart shown on comparative engine speeds...

It is significant to note that at 3600 RPM the automobile would be traveling at a speed of over 100 MPH.

Note: This comparative chart was made by installing a tachometer on my 1960 Pontiac car and may be considered comparable to the average automobile.

R. Mack Krebs
General Service Manager
Chris Craft Corporation
January 15, 1961

I have long been a proponent of basing wear and service intervals upon fuel burned, not hours run.