Page 18: of Marine News Magazine (June 2022)

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Column

Propulsion

Danny Gonzalez / U.S. Marine Corps

Propulsion Systems for Patrol Craft

By Jeffrey Bowles, PE, PMP, Director, DLBA Naval Architects,

A Division of Gibbs & Cox, Inc., A Leidos Company

A U.S. Navy Mark VI patrol boat with waterjet propulsion.

more unique characteristics worth noting.

The propulsion system

Ensuring that the marine propulsor is appropriately sized is a critical part of all patrol craft. There are different types for the application is the number one consideration. If the of propulsion systems available for use on these craft, and system is undersized or oversized, its performance will be selecting the “best” one for the application at hand is not sub-par, and the negative impacts could be around to haunt to be taken lightly. You will note that I used “best” in the operators for the life of the vessel. The primary factors as- quotes, which I’ve done to hint at the subjective nature of sociated with the correct sizing of the propulsor are 1) thrust the decision. Propellers, waterjets, sterndrives, outboards loading, and 2) mechanical strength. In short, the propulsor – they are all commercial off the shelf technologies which must operate within acceptable thrust loading boundaries are mature and used in different patrol craft applications. (which are a function of vessel speed, thrust output, and

They offer similar performance and reliability (provided blade area) to provide good ef? ciency (fuel economy) and they are sized appropriately), and each type offers one or avoid cavitation (low noise and vibration). Secondly, the

An example of a sterndrive unit.

Konrad Marine

MN June 2022 18 |