The machinery on board is very similar, on a smaller scale, to that carried on the ill fated "Titanic", which makes "Shieldhall" a unique link with the past. The following is a brief summary, to find out more, come aboard this wonderful ship and see for yourself.
|Breadth||44 Feet 6 Inches|
|Draught||13 Feet 6 Inches Aft|
Two Scotch boilers, each 12ft diameter and 12ft long, produce saturated steam at a pressure of 180lb/sq.inch. The steam powers the main engines, auxiliary engines, all the deck machinery and a 25kW electrical generator (a diesel generator has been added to power modern navigational equipment).
The boiler is of riveted construction and has approximately 320 firetubes. Fuel oil is forced under pressure to provide an atomised spray which is then burnt in the furnace. Air for combustion is supplied by a single-cylinder, forced draught fan. To improve efficiency, the air is heated by the combustion gases before they exit from the funnel.
For the non-technical: "Shieldhall" has two large, oil fired boilers providing steam power throughout the ship. They are similar, although smaller, than those used on the "Titanic".
The first Scotch boilers were introduced in 1862 to meet the need for higher steam pressures than hitherto existed. The boilers are robust and contain a relatively large volume of water to produce the accumulator effect necessary to meet variations in demand for steam. Originally designed for coal firing, later boilers such as those installed on “Shieldhall” were fired with oil or gas.
Scotch boilers were introduced into the Royal Navy for the first time in 1890 on HMS “Trafalgar”. Oil fired Scotch boilers, albeit larger than those on “Shieldhall”, were used for steam raising on the largest Trans-Atlantic liners, such as the RMS “Mauretania” and RMS “Titanic”, in the early 1900’s. On “Shieldhall” the two Scotch boilers, each 12 feet in diameter and 11 feet long produce saturated steam at 180psi and are fired with heavy fuel oil.
The two main engines were constructed by the ship's builders, Lobnitz & Co., of Renfrew, Scotland. They are triple expansion engines with cylinder diameters of h.p.15", i.p. 25" and l.p. 40", and the stroke of 30". Each engine can provide up to 800 horse power to its screw. The normal service speed is 9 knots at 86 rpm. This is our economical speed, although the designed maximum is 13 knots at 120 rpm.
Waste steam from the engines, is ejected to a condenser where it is cooled by sea water passing through the heat exchanger tubes. The condensed steam is held in the hot well before being pumped back to the boilers as feed water.
For the non-technical: Two steam engines drive the ship and to avoid wasting water, the steam is condensed back to water and re-used.
Triple expansion steam engines were first developed by Liverpool shipowner W.H.Dixon in 1874 for his steamer SS “Propontis”. This type of engine was soon adopted for large passenger liners, such as the SS “Majestic” in 1899 and was first introduced into the Royal Navy in HMS “Duncan” in 1900. The engines produce large amounts of power at relatively slow speeds, they are therefore reliable and are easy to maintain and operate. Due to the strong construction inherent in the design and the slow speed of operation, components had a long life enabling the engines to work for many years between major overhauls. On “Shieldhall”, the two main engines are triple expansion steam engines built by the ship’s builders. The cylinders are 15 inches for the high pressure, 25 inches for the intermediate pressure and 40 inches for the low pressure cylinder; the piston stroke is 30 inches. The low pressure cylinder exhausts to a condenser thereby improving the cycle efficiency and allowing the condensate to be recovered. At full load, each engine develops 800 horsepower. The engines are of open crankcase construction as required by the owner even though by that time the arguably superior enclosed crankcase design was in existence. Like the boilers, the engines are typical of machinery that powered ships throughout the steam age. Prior to the widespread introduction of the steam turbine following World War 1, even the largest steamships were driven by reciprocating engines and this type of engine remained in service on cargo ships throughout. The famous Liberty ships, of which more than 2700 were built, were powered by triple expansion steam engines; the British equivalent “Empire” ships and the Canadian “Forts” both of which were also built in large numbers during World War 2, were similarly equipped. The main reasons being, cheapness and simplicity of construction and a reliable engine. The triple expansion steam engine is therefore synonymous with ship propulsion over the richest period of Britain’s commercial maritime history.
There are 20 steam engines driving all of the original machinery. Modern diesel and electric machinery supplements power and firefighting capabilities.
Starboard Reversing Gear
Port Reversing Gear
Cooling Water Pump (2)
Condenser Air Pump (2)
Boiler Feed Pump (2)
General Service Pump
DC Electricity Generator
Fresh Water Pump
Fuel Oil Pumps (2)
Fuel oil Transfer Pump
Forced Draught Fan
Other onboard equipment
This is a two cylinder, fixed lap and lead reciprocating steam engine which alters the rudder angle through a rack and pinion arrangement working on the rudder quadrant. Rudder movements are transmitted from the ship's wheel on the Bridge by hydraulic pumps which form part of the wheel assembly. Control of the steam input is via a control ram working on a closed loop feedback which adjusts the steam inlet valves accordingly.
The for'd windlass and capstan and the after capstan are all operated by steam generated by the main boilers. They are normally used to moor the ship and to recover the anchors. The machinery to launch and recover the lifeboats and operate the cargo derrick, is all Armstrongs patent, i.e. muscle power.
Bridge and Navigating Equipment.
On entering the bridge, the first item of equipment that you pass is the engine room telegraphs. These are situated on both bridge wings and by means of chains, relay the required engine movements to the engine room.
Within the charthouse, there is a traditional ships wheel and binnacle. The course to steer can be by reference to the magnetic compass within the binnacle, or the modern gyro compass, mounted on the deck head.
There are various items of electronic equipment which are required to navigate "Shieldhall" from port to port and an item of interest is the Decca Radar set which dates from the early 1960's and is still operation. It is normally used as a standby to the modern set located on the chart table.