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Balmoral's correct title is 'M.V. Balmoral'. The M.V. is short for motor vessel and is one of a number of prefixes used to describe how a ship is powered or what it is intended to do.
STEAM V DIESEL
Diesel engines are very much more efficient than steam engines as they are smaller and don't need huge boilers and complicated piping systems and condensers to return steam to the boilers for reuse. Diesel engines are also smaller for the same power output and just need fuel oil - also known as 'marine gas oil' ( not the same as gasoline which is the American word for petrol ), they don't need a constant supply of fresh water to turn into steam and a complicated system of burners to heat the boilers and warm the fuel to stop it becoming too thick to pump to the burners! This means that as well as being cheaper to run, the engines take much less space in the ship, so for a given size, you get a lot more load carrying space. Diesel engines also use far less fuel as they are more efficient at turning energy from the diesel oil into motive power. In a steam engine around half of the energy is lost up the funnel as waste heat, whereas a diesel converts around two thirds. This makes a diesel engine ship cheaper to run and more economic. There are still cases where a steam engine is more cost effective, but this is very rare and only applies to very large ships fitted with steam turbines. In general steam powered ships are either used because they are historic or as leisure vessels for passenger service. Other advantages of a diesel are that it starts immediately; a steam ship can take many hours to raise enough steam to turn the engines, the engine is much faster to respond to the controls , needs far less maintenance and does not generate huge amounts of heat inside the ship. The disadvantages are noise, vibration and in some cases the need to reduce the speed of the final drive as the engine turns too fast for a propeller to be efficient, although in the case of the Balmoral's original engines they turned slowly enough to coupled directly to the propeller shafts.
BALMORAL'S FIRST ENGINES
As she was built, Balmoral was fitted with two Newberry Sirron six cylinder direct reversing 2 stroke diesel engines. These were made by the Russell Newberry Company and were designed by a man named H Kent-Norris, who was an engineering graduate of Bristol University. The company reversed his name to make Sirron, and that name was used for a range of highly successful marine 2 stroke diesel engines.
The ship was originally intended to have 8 cylinder engines and a higher speed, but a cost saving was made by reducing the power and fitting smaller engines. This gave more space in the engine room but also meant that the ship was more heavily built. This has helped her to survive over half a century of hard use - and in later years the extra space and layout of the engine room enabled new more powerful engines to be fitted.
The original engines were 2 strokes but not like a bike or chain saw engine. They did not need oil mixed with the fuel - and they were diesel anyway - but rather than having valve gear, the engine had a large air compressor that used high pressure air to push the exhaust gas out of each cylinder with each turn of the crankshaft. This meant that compared with a 4 stroke engine with valves, the engine had double the number of power strokes in each cylinder - in a four stroke engine there is a power stroke every other cylinder cycle, but with a two stroke there is power on every turn of the engine. This gave a much higher power to weight ratio, so for the given size of the engine, the ship could go faster. As she was being used as a ferry on the Southampton to Isle of Wight Service, this was not important on her day job, but it certainly was when she was used for her other purpose, that of a passenger cruise ship when she needed to take holiday makers along the South Coast. Then the additional power of her engines was very useful and the ship could make 16 knots. However a 2 stroke engine is not as efficient as a 4 stroke where the gas flow is controlled by valves.
Each engine appeared to have an extra cylinder, but the one at the 'front' was actually the compressor for the scavenging system that cleared exhaust from the cylinders.
This can be seen on the left photograph with the large circular cover on top.
These evocative photographs by Richard Mills bring back the noise, heat and wonderful smell of warm oil as Balmoral's two Sirrons push her up Channel on a chilly Autumn Evening towards the lights of Weston super Mare.
Note the spare piston and con rod on the brackets above the Starboard engine ! The photo is looking aft ( backwards ) so left and right seem the wrong way round.
The engines may have been powerful, but being 2 stroke they were not as efficient compared to a modern 4 stroke engine and created a lot of smoke at full speed as the fuel was not burned very efficiently, so Balmoral always had a dirty funnel and her smoke was a feature of the ship. As she got older, her consumption of lubricating oil increased dramatically and towards the end of her time with P & A Campbell on the Bristol Channel, she was always seen with 200 lts drums of Shell 'Rotella' marine lubricant in the engine room alleyways, ready for topping up her tanks. ( model photograph below ).
The engines were direct coupled to the propeller shafts, and to go astern, the engine was stopped and started again in reverse. It was a very simple way of operating the ship, and stopping and restarting was very much faster than slowing the engine down, shifting gear and then speeding it up again. She did not need a gearbox or reversing system and as the engine had no valves, it ran just as efficiently in either direction. This made a much cheaper and lighter installation and saved money, servicing costs and maintenance. The engines were started by compressed air and there was a large cylinder beside each engine that provided a number of starts. As each ahead/astern manoeuvre required a blast of air and she had two big engines, this gave a finite number of engine commands before the air supply was exhausted. If the Captain messed up an approach to a pier, perhaps in bad weather and had to have another attempt, it was sometimes possible to hear the engine room warning siren go off, indicating that the air pressure was getting low. In this case Balmoral would have to give up trying to go alongside and steam round the bay for a while until there was enough pressure in the tanks to continue manoeuvring. She had a separate compressor to top up the air tanks for starting from cold, so she was never unable to operate, but as she was intended for use in the Solent which is a sheltered area, the designers never anticipated she might run out of compressed air during the complicated engine movements needed for some Bristol Channel piers, Weston being the most difficult.
For more information on the Newberry Sirron range of engines, http://rowifi.com/ndc/mv-balmoral.html
As already described in the section on the bridge, the engine commands were signalled to the engineers by means of a telegraph dial indicator with a back up of lights plus a bell and finally a speaking tube. This required an engineer to be at the controls of each engine whenever the ship was near a pier of harbour. On a modern ship the captain can control the engines directly with a control on the navigation bridge, but with the telegraph system, everything had to go via the engineer who set the engine controls in accordance with the captain's instructions. Although it was found that the Sirron engines originally fitted to Balmoral were about 5 seconds faster to react than her later engines that had gearboxes, there is always the impression that using telegraphs and engineers to respond to instructions removed some of the direct response that can be achieved if the engines are under direct bridge control. However in practice this is not the case. While it does mean that two duty engineers need to be available, when the Captain and his engineers had worked together for some time, it was claimed that a good team could interpret the way the telegraphs were rung by the Captain and as a result he had better control of the ship as the engineers were able to interpret his commands far better than if he just moved a lever on the bridge!
The photographs below show Balmoral in 1975 with her Sirron engines. They were noisy, dirty and not particularly fuel efficient, but they were incredibly reliable and never once let the ship down when in service. When they were changed in 2003 the engines were initially given to a museum but were found to be completely worn out and were scrapped. This was rather sad as there are not many types of this engine left.
During a voyage, only one engineer needed to be on station at the controls but two had to be immediately available - one for each engine !
The controls for the Starboard diesel can be seen on the back of the crankcase.
The tank on the walkway is a portable fire extinguisher !
A common site in the Campbell's days - a piston and associated piston rings on the engine platform ready to be fitted during an off service day.
The engineers not only operated the machinery but did the servicing each winter and it was not unusual for a major job to be undertaken during the ship's weekly day off duty !
The large white pipe behind the piston rings is the insulated exhaust pipe leading to the funnel above.
In 2003 Balmoral was fitted with two 4 stroke Danish built Grenaa diesel engines with separate gearboxes and new propellers.
These were more powerful and much more fuel efficient, giving the ship an extra 2 knots in speed.
Engineer control was continued but new emergency signalling was installed and the engines are much more economic to operate.
Each engine has its own log book and full maintenance records as can be seen in this photograph. The gearboxes are under the 'tables' and the photographer is standing between the engine controls.
This is the engineer's position for the Port ( left ) engine. You can see the main telegraph, the emergency communication system and the brass topped pedestal with the engine and gearbox control lever on top. The main engine instruments are on the black board. To the right of the control pedestal is the main gearbox with the shaft coupling under the white circular cover. You can see the silver propeller shaft as it heads towards the stern of the ship.
The engine room is a mass of pipes, tanks , diesel engines and electric motors of various shapes and sizes ! In the lower photograph are three Lister Diesels from 1949 - Two electrical generators and a compressor to supply high pressure air for starting the main engines.
For a short video of the engine room : https://www.youtube.com/watch?v=F5EwJSG3q1s