There’s nothing particularly complicated or overly technical about a narrow boat’s propulsion system.

Designs have to be rugged and well constructed to cope with the harsh environment that is to be found when cruising the inland waterways of the UK. The design and application of engineering solutions has been honed since the move from beasts of burden to steam in the 1820’s.

Here, we will look at a basic narrow boat system by way of an introduction and then move on to the latest developments and choices available in the current market.

So, very simply: the narrowboat engine is connected to a gearbox. A flange exits the rear of the gearbox to which is attached a steel shaft known as the propeller shaft. This shaft exists the stern of the boat and terminates in the propeller.

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 craft through the water. If it were really that simple…

The shaft has to exit the hull and be sealed to the ingress of water. It exits the hull through via what is know as the stern tube. The tube provides location for the shaft and a bearing surface. In order to seal the engine bay from the outside water as the shaft exits the shell it passes through what is known as a stern gland or stuffing box (traditional term).