User

Here's a suggestion for one of your future technical articles.  I recently posted information on the Engine/Technical Section of the Message Board entitled:

"Bow Thrusters—Broken Shear Pins." My situation/question is generating quite a bit of "discussion" on the causes of broken shear pins. I would really like to hear your views on the subject.  I always enjoy reading your articles, no matter what the subject!

Ken W

Bow thrusters may be equipped with shear pins in two locations, at the propeller itself or at the transition between the drive leg and the electric motor.  Ideally, the pin is designed to break or shear if the propeller becomes jammed with debris, a fish or anything else that might prevent it from turning.  The shear pin fails rather than the aforementioned more expensive components and when they do so they’ve succeeded in doing their job.  Thus, the pin shouldn’t be blamed as defective or inferior unless it’s failing repeatedly and for no apparent reason.  This may happen because the pin is defective or undersized.  Or, the shear pin between the motor and drive leg may fail if the two components are improperly aligned, a fault that occurs during the installation process.  If your failures are falling into the former of the two, repeated failure for no apparent reason, then it’s time for a discussion with the manufacturer (not just a dealer).

Steve D.

PMM Tech Editor