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When canals where first built back in the 18th century the boats that used them were all pulled by horses, mules or donkeys, at the time diesel engines had not been invented, and although steam engines were invented around 1698 they were much too crude in design to be used in boats, so in fact apart from pulling the boat by hand, the horse was the only method available. As early as 1787, steam engines were used in much larger boats , but due to the size and weight they were still not suitable for narrowboats.
This carried on till the late 19th century, when around 1889 a specially developed compound steam engine was used in some narrowboats. Fellows Morton & Clayton were one of the first companies to use these steam engine driven boats and built 31 of them between 1889 and 1931. One of these boats 'President', is still working and is owned by the 'Black Country Living Museum' and along with the butty 'Kildare' also owned by the museum, travels the waterways visiting boat festivals and events, to help promote the inland waterways.
The problem with useing these steam engines was the weight, not just the weight of the engine, but the weight of the coal or coke used. The load that could be carried was down by seven tons compared with a horse drawn boat, but the fact that the power generated by these engines meant that one or more other boats (buttys) could be towed greatly increasing the payload for each journey. The steam engines at that time were not totaly reliable and horses were still being used in places as late as the 1940's.
Although the diesel engine was invented around 1890, it was not untill the 1920's that a diesel engine was produced that was thought reliable enough to be used in narrowboats, and even these were a far cry from the modern diesel engines of today, but again the power from these engines meant that a butty could also be towed, increasing the payload again.
The diesel engines prior to the 1920's ran on vegetable oil, strange that some quarters today are promoting the use of biofuel again.
Some of the earliest diesel engines used in narrowboats were a different design and called semi-diesel or hot bulb engines, this type of engine has to be pre-heated usually with a blowlamp and therefore are definitely an enthusiasts engine. Although at the start of the 20th century there were hundreds of firms making these engines, one Swedish firm Bolinder had 80% of the market. There are still some boats around from the 1920-30's that have these engines installed, and are always one of the main attractions at boat shows. The engines being two stroke have a very distinct slow running sound and once you have heard one, it is a sound you will never forget.
Other popular engines at the time were made by National, Gardner, Lister, Russell Newbery, Kromhout, Petter and Armstrong Siddely.
When someone has a narrowboat built nowadays and wants a vintage engine installed the usual choice is Gardner, Lister or Russell Newbury. Usually the engine will be rebuilt before going into the boat and will last for many, many years and should be the owners pride and joy.
There are many different models of Lister engines, 2, 3 and 4 cylinder, water and air cooled; some date back to the 1930's, but the models SR2 and SR3 became very popular with boat builders in the 1970's when narrowboats started being built for the leisure industry, both very reliable engines but the SR2 in particular used to vibrate a lot, and both were quite noisy. Both these engines, one 2 cylinder and the other 3 were originally designed as stationary engines for farm elevators and pumps etc. But the fact that they were air cooled meant they could be used in narrowboats without too much alteration, all they needed was a gearbox matched up to them and the addition of a starter motor and alternator. Some didn't even have a starter motor and were started by hand with a handle.
Another popular engine in the 1970's and 80's was the water cooled BMC 1.5 and 1.8, lot's of these are still around and most spares are readily available, another advantage of these engines is that they use a timing chain and not a belt, this cuts down on maintenance as timing chains are usually good for at least 30 years. The alternative water cooled engine at the time was the Perkins 4.107 which is now obsolete.
In the 1990's and to date diesel engines have become more sophisticated, and several makes of engine are marinised ready to be installed in narrowboats. Popular makes of engines now are Vetus, Beta Marine, Thornycroft, Lister Petter, Isuzu, Barrus, Nanni, Lombardini, Kubota and Yanmar.
A new modern engine requires little maintenance, topping up the oil and water when needed; and oil, filters and timing belt changes at the correct intervals. Maintenance intervals are counted in hours the engine has run on a narrowboat as opposed to mileage on a car.
All engines need to be kept cool, and because a narrowboat engine is usually housed in a small space at the back of the boat a car type of cooling system with a radiator and fan is unsuitable.
Most engines still use a sealed water-coolant system where cooling is achieved by the water passing though a heat-exchange panel (skin tank) attached or built into the interior of the hull below the waterline and then back to the engine.
Some other engines are air-cooled drawing colder air from outside the boat via a ducting, the hot air being expelled the same way at the other side of the boat.
Another type of cooling system that is only used in older boats uses raw canal water, the raw water being drawn from the canal through the hull under the waterline, taking the heat from the sealed system in a heat exchanger and then being ejected through the hull above the waterline. Very rarely you may find a raw water system where there is no sealed primary system, the canal water itself passing through the engine block’s narrow waterways, acting as the primary coolant, before being expelled. All raw water systems are prone to blockages and require filters or mud boxes which need cleaning out regularly.
The usual method of taking power from the engine is through a gearbox to the prop shaft and then the propellor. The gearbox usually has just one forward and one reverse gear and no clutch is needed. This method requires that the engine is mounted centrally and as close to the propellor as possible to keep the length of the prop shaft to a minimum.
Another method is where the engine powers an hydraulic pump mounted on the bell-housing where a gearbox would normally be. The pump is in constant mesh with the engine all the time. The pump is fed with oil from a reservoir tank through a strainer and in idling mode, oil is circulated via the control valve, which provides the function of a conventional gearbox, then back to the reservoir. When forward or reverse gear is selected via a conventional lever and cable the control valve forces fluid in the appropriate direction through the hydraulic motor which is connected to the propeller before returning that fluid to the reservoir. The hydraulic motor can be mounted to a conventional shaft and stern tube as in normal inboard installations, or in newer systems the hydraulic motor is mounted directly in the keel of the boat just in front of the propellor, a prop shaft is not needed with this method and therefore there is no vibration. A heat exchanger type oil cooler is fitted into the system to cool the hydraulic oil, which must be kept topped up. The advantages of using an hydraulic system are that the engine does not need to be in line as no prop shaft is used, in fact the engine could be placed anywhere in the boat. Also if a big enough hydraulic pump is used, it can be used to drive a bow-thruster as well.
Another way of propelling a boat is by diesel-electric, this system possibly started when Beta marine started to produce the 'Propgen', this is a 4 cylinder 2.2 litre diesel engine directly coupled to an 11.3kva 240v generator, in a noise reducing cocoon. They also produced a smaller version the 'Mini Propgen' with a 5.7kva 240v generator. The propgen and Mini Propgen are cocooned in a soundproof box and therefore can be positioned anywhere in the boat, usually under the bed. The engines run at a constant 1500rpm, and generate more than enough power to propel the boat via ann electric motor. Boats that use the Propgen are usually all electric, as the power generated can run electric cookers, hobs, microwaves, washing machines and driers etc. so it would be pointless wasting this power by using a duplicate gas system for cooking etc. The generator also charges the battery bank, which can power an inverter which will give 240v for running a tv etc in the evening. Unfortunately Beta Marine stopped making the Propgens' in 2007 due to lack of demand.
Recently after 8 years of research and development a firm called Hybrid Marine have designed a parallel diesel electric propulsion system. This system still uses the engine, gearbox and prop shaft of a normal drive, but has an electric motor/generator running in parallel.
In normal canal conditions you can drive on the electric motor for prolonged periods. How long you can go on electric drive depends on the size of your batteries. A 48V / 400Ah battery bank would last around 3 to 5 hours, a larger bank of around 48V/800Ah would last 6-10 hours. Keep in mind this is continuous operation. If you are transiting a flight of locks then you are only using electrical power when moving. This eliminates idling the engine in locks and provides considerable savings in fuel. When the batteries run down you start the engine and drive in the normal way. At this time the hybrid automatically becomes a generator to recharge the batteries. At typical propulsion speeds the batteries are quickly recharged via the powerful 7kW hybrid generator. Every hour of engine drive can store enough energy in the batteries to travel between 1 and 2 hours in electric drive. After the batteries are recharged you can go back to electric drive or save the energy stored for powering your electrical circuits in the evening. At the moment this system can only be used with the Beta engine, supplied complete; but Hybrid Marine are also developing a "retro-fit" system which can be fitted to popular models of existing engine and may in the future develop a "serial hybrid" solution which uses electric propulsion with the diesel engine generating the electrical supply.
Apart from being the power to propel the boat, the engines job is to supply electricity to run the various electrical items on the boat. This is done through an alternator which charges both the starter battery and the leisure batteries. On some higher powered engines two alternators are used, a smaller one to charge the starter battery and a higher rated one to charge the bank of leisure batteries. A lot of boat owners opt to have an alternator booster or battery management system fitted which increases the amount of charge that can be put into the batteries.