Motor Plants & Auxiliary Boilers USCG Question #265 (Set 6)

A diesel engine with a full speed of 1000 RPM drives a propeller at 300 RPM. What is the speed reduction ratio?

Official USCG Answer & Rule Citation

Correct Answer: Option B — 3.33 to 1

Speed reduction ratio is calculated by dividing input crankshaft RPM by output propeller RPM (1000 divided by 300), yielding a reduction ratio of 3.33 to 1.

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