One of the first vessels that Andrew Brown, a trained naval architect, was involved with when he moved to Simons was the fast paddle steamer Rothesay Castle which became engaged in the intensely fought tussles of speed for the lucrative Clyde passenger traffic. These steamer races wereoften conducted to quite irresponsible levels of disregard for public safety although it has to be noted that many of the passengers seemed to revel in them. Rothesay Castle's great rival was the paddle steamer Ruby, built 'next door' and Henderson's West Renfrew yard. Her master, Capt Richard Price, has ben described as a 'maniac' because of his attitude to racing his vessel. Then, along came the American Civil War and the fastest Clyde paddle steamers were snapped up by the agents of the Confederate States, Their light draught and speed made them ideal for passages between Nassau and the Southern States through shallow waters, giving them a good chance of evading the much deeper draughted blockading Yankee warships. Rothesay Castle left the Clyde for Nassau in 1863. Many of her contemporaries were eventually captured or sunk but Rothesay Castle survived the war and went back into commercial service - in Canada - surviving until around 1889.
In his view the levers driving the slide valves that contolled the admission of steam to the cylinders can be seen at the top of the engine, connected to the eccentrics on the crankshaft