Checking the stern gear on a narrowboat
<< Back to Blog list
Tue May 29, 2018 at 12:52pm

Checking The Stern Gear on a Narrowboat will need to be done when the boat is out of the water for a blacking of a hull survey as you will need to get underneath the boat to locate it. It is extremely important that you ensure that the engine is switched off before embarking on a stern gear check.

What is a stern gear?

A Stern Gear is the general term for the propeller, the propeller shaft and any supporting brackets or bearings. The stern gear assembly is a general term used for the part of the boat that couples the engine to the propeller.

What to check for

There shouldn't be an excessive amount of wear or movement in the stern gear assembly, although a small amount of wear is tolerable as long as the stern gland is kept packed. Turn the propeller by hand to make sure that it moves freely, and give it a tug and a wiggle to test it for movement. If there is a lot of movement inside the stern and bush assembly you can get water ingress through that part of the boat which could fill the engine bilge area around the engine. You need to take a good look at the stern gear to see it's general condition by scraping off any weed, encrustations or paint which could have accumulated on the propeller. Another way of checking is to use a coin to tap the propeller with to see what sound it makes; if it rings like a bell it is in a good condition, if the sound is dull it is electrolysed and will need replacing. You should visually inspect the stern gear to make sure it's in good condition and check all the assembly components. Check for bent or dented blades, check for cracks and corrosion. If bent or dented the blades may be able to be straightened or filled by a professional.

If you are in any doubt ask a marine surveyor or a marine engineer to visit to check the stern gear, better to be safe than sorry whilst the boat is out of the water.

Watch our YouTube video below for a demonstration of how to check your stern gear and assembly.


We re-iterate; For safety reasons is extremely important that you ensure that the engine is switched off whenever you are working near the propeller on any boat. This blog is for information purposes only, Whilton Marina cannot accept any liability.