With the aid of a Museums Galleries Scotland grant, the Scottish Maritime Museum at Irvine has produced a 3D model of Waverley's original 1947 boiler.
Stuart Cameron kindly provided the following description of the boiler:
The original double-ended Scotch boiler was built at Rankin & Blackmore's Eagle Foundry in Baker Street, Greenock, Scotland and fitted into the then new paddle steamer Waverley as she lay in the Victoria Harbour, Greenock in the spring of 1947.
The boiler was originally intended to be oil fired but due to a shortage of equipment in the post WW2 period was fitted with manually-stoked, coal-firing grates. In the days before dedicated forced draught fans, the boiler was operated on the old fashioned 'forced draught on a closed stokehold' principle. The boiler was converted to oil-firing when equipment became available in the 1950s.
Waverley's double-ended Scotch Boiler was first steamed in May 1947 and served the steamer's triple expansion reciprocating engine, also a product of the Eagle Foundry, until the end of September 1980.
The boiler was removed from Waverley's boileroom by the large cantilever crane at Finnieston, Glasgow in March 1981 to be replaced by a new Steambloc TC50 boiler built by Babcock Power of Renfrew.
After removal from Waverley, the Scotch boiler was purchased by the Museum of Scotland for preservation as a type of boiler, originally developed in Scotland but, ultimately, built in engineering workshops around the world. Unfortunately, due to inadequate funding the boiler was stored outdoors for many years at the SRPS premises at Bo'ness before being moved to the Scottish Maritime Museum at Irvine where it has been exhibited but again externally. Sadly, as a result of having now spent more than half of its 72 years exposed to the Scottish weather the mechanical condition of the boiler is very poor.
The Scotch boiler is generally held to have been an invention of the Scottish engineer James Howden in the mid 19th Century but it was developed significantly by others. The double ended version (like two boilers back-to-back) was developed particularly for marine applications, offering weight savings over equivalent capacity single-ended boilers. Eventually, the term "Scotch Boiler" became associated with a type of boiler rather than a boiler manufactured in Scotland.
You can rotate, zoom and view the boiler plus other Scottish Maritime Museum artifacts on the Sketchfab website here.