Narrowboat gearboxes are rugged affairs. Gearboxes are complicated feats of engineering so we will just describe the concept.

Usually the gearbox is a basic one. Commonly controlled by a single lever at the helm the skipper is able to select forward, neutral & reverse. There is no need to operate a clutch, simply moving the lever will engage drive, very different to the sophisticated electronic gearboxes found in modern vehicles!

Moving the lever into the ahead or astern position engages the appropriate gear which drives the propeller shaft, which has the propeller attached to the other end. The rotary motion of the propeller moves the narrow boat through the water.

Narrowboat gearboxes require regular checking changing of their oil. Some types are designed to use engine oil, other special transmission fluid.

Remote oil coolers are fitted to some models which use the return cool water from the skin tank to cool oil circulated through a small heat exchanger.

The system itself is all very simple.