Military steam tradition
Naval steam Pinnace P199 is an exhibit of the Royal Navy National Museum Trust, Portsmouth. Built by J Reid of Glasgow and completed in August 1909 she spent a short period as the Admiral’s barge with Battle Cruiser HMS Inflexible. She was then stationed at Portsmouth undertaking general duties before being assigned as the Captain of the Port’s barge, where she remained for her time with the Royal Navy.
In 1952 P199 was sold off into private ownership for use as a Thames houseboat. She was named Treleague and her steam plant was removed and replaced by a petrol engine. She was later bought for restoration by an antique dealer but sadly, funds fell short of what was necessary to complete the task and she was acquired in 1979 in a very sorry state by the Royal Navy Museum (now the National Museum of the Royal Navy, Portsmouth). She . acquired a second-hand boiler from a similar craft and in 1984 was recommissioned and used occasionally for ferrying VIPs, being exhibited until 1998 in the Mast Pond at Portsmouth Historic Dockyard. She was then taken to the Maritime Workshop in Gosport for a complete refit.
Between 1999-2001 the engine was rebuilt and the boiler overhauled ready for P199 to take part in the ‘Festival of the Sea’ celebrations two years later. She was awarded the Hugh Casson Trophy by the Steam Boat Association for the standard of her restoration.
In 2011, a full survey revealed the need for further extensive restoration and this was linked to additional work necessary for her boiler certification to be renewed.
From 2012-2015 a team of volunteers, supported by donations and a Heritage Lottery Grant, carried out some 13,000 hours of work on her hull and power unit.
Steam Pinnace 199 is today something of a hybrid, having armament forward and the accoutrements of an Admiral’s Barge aft. She is believed to be the last remaining operational vessel of her type, her steam plant still providing reliable, powerful service.
Manufactured by A G Mumford of Colchester in 1910, the compound engine produced 162hp at 300rpm. At maximum speed under trials P199 achieved 12 knots at 624rpm.
By 1914 the Navy had some 634 examples of this type of small steampowered maid of all work-type vessels.
Interestingly, like many other larger naval steamers, her boiler was located in a separate pressurised compartment to ensure a good through draught for the fire. The Yarrow-type water tube boiler was built by the Thames Iron Works in 1898. Originally coal fired during the 1920s, P199’s boiler was converted to burn diesel oil.
The boiler room also contains a bilge pump for drawing water from any of the five compartments, transferring feed water from either the reserve feed tank or the hot-well into the boiler as well as pumping sea water when required. n nmrn-portsmouth.org.uk
‘Steam Pinnace 199 is today something of a hybrid’
Comparisons indicate that an efficiently designed water-tube boiler (like steam Pinnace 199’s – see panel, previous page) produces roughly twice the amount of steam as a fire-tube type for an equivalent surface area exposed to heat.
The engine
On small steam launches the engine driving the propeller is usually a vertically mounted device consisting of one or more cylinders in which pistons are driven both up and down by steam pressure giving two power strokes for each cycle. Twin cylinders can be in-line or even in a ‘vee’ arrangement and the engine is most usually open to the elements so its many moving parts make a fascinating spectacle.
Marine steam engines are built to run in both directions, steam distribution to the cylinder(s) being controlled by a reversing gear exactly as in a railway engine, so no reversing gearbox is needed.
Often found in small launches are ‘compound’ engines, where the same steam is used twice, first in a cylinder of slender bore then in a much larger bore cylinder of the same stroke. This ‘expansive’ process makes for an economical use of steam.
To control steam emission is a simple regulator valve. Critically, because steam engines generate large amounts of torque they tend to run very much more slowly than petrol or diesel engines and will drive larger, more coarsely pitched propellers.
Camaraderie
“Steamboat ownership can be a time consuming hobby. We do it for the passion and the pleasure,” said Rev. Rudall. “In addition to maintain the hull in a seaworthy condition, the engine will respond to sympathetic maintenance – while the boiler must be prepared carefully for annual inspection.”
The shortfalls of marine steam power is the space engines and boilers consume, especially in smaller boats.
Care must also be taken when carrying passengers to ensure that as they move around the craft they avoid touching anything hot.
And you can never be a hurry with a steam engine. Boilers will take time to build up steam pressure before the boat can get under way after the fire or burner is lit – but this waiting time is often put to good use for lubrication and polishing.
Then there’s the camaraderie of meeting other like minded enthusiasts.
“A huge part of the enjoyment comes from managing the power plant to get the best from it, closely followed by the awareness that you’re bringing something rather beautiful and unusual to the waterways.
“Buying or building a steam launch forms the beginning of a journey, an adventure which can become totally absorbing and gradually take over the owner’s life.”
Thanks go to Rev. Mark Rudall and Martin Marks for their considerable help with this feature