Boating Terminology – Engines
If you’re a narrowboat novice, you’ll often find that fellow boaters are happy to share their knowledge and experience. In addition, getting to grips with the terminology helps to increase your understanding of all things boating.
Narrowboat engines – the basics
The engine is located in an engine bay towards the back, or stern, of the boat. It may be inside or outside the cabin depending on the type of narrowboat design.
Underneath the engine bay is a chamber known as the engine space bilge. It runs along the bottom of the hull and is where water, from condensation or leakage for example, collects.
Water can be pumped out using a bilge pump. The engine space bilge also has a stuffing box or packing gland, which is an adjustable gland to help keep water out.
The vast majority of narrowboats are powered by diesel engines. These can range from vintage models to modern electronically-controlled units, but they all use the same fuel and work on the same basic principle.
Unlike a petrol engine where fuel is ignited by a spark, the ignition process of a diesel engine uses very high cylinder compression.
Instead of spark plugs, a diesel engine uses ‘glow plugs’. These are located in the top of the engine’s cylinders, near to the fuel injectors. Glow plugs pre-heat the combustion chambers prior to compression, in order to start the engine running.
Some narrowboats will have a position on the ignition key to activate the glow plugs, while others will have a separate button.
Once the engine has started, the vertical motion of the pistons in the cylinders is converted to rotary motion by a crankshaft, which is then used to drive a gearbox. This in turn is attached to a propeller, which moves the boat forward.
Types of engine cooling system
The type of cooling system that a narrowboat has will depend, to some extent, on the age of the boat. There are three main types of cooling system:
- Keel cooled system – this type of system is used in most modern engines. The engine is cooled by the flow of water through a tank at the stern of the boat.
- Raw water cooled system – this takes pumped water from the canal, which is pushed around the engine and uses a heat exchanger to cool it down, before returning to the canal.
- Air cooled system- this works on the same principle as a car engine and relies on a flow of air to keep the engine cool.
Stern gear – terminology
Another key component to the operation of a narrowboat is the stern gear. Here are some of terms that you’ll need to understand.
The stern gear – a general term for the propeller, the propeller shaft and any supporting brackets or bearings. It is positioned towards the back of the hull below the water line.
The stern gear assembly – a general term for the parts of the boat that connects the engine to the propeller. They convert the rotating motion of the engine, via the gearbox, into forward propulsion of the boat.
Stern gland – a greased component that prevents water from entering the narrowboat via the stern tube.
Stern tube – the point where the propeller shaft passes through the hull.
Remote greaser – a metal cylinder fitted close to the stern tube that contains grease to keep the stern gland lubricated.
Fuel, water and electricity can be a dangerous combination, so never attempt any maintenance or servicing of your narrowboat engine unless you know exactly what you’re doing. Always seek professional help if you’re not sure. We hope that this introduction to some of terminology relating to narrowboat engines will help you to converse with the experts.
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