Relief Crew 21: Jet-Propelled Paddle Steamer

Oops!  I meant this for tomorrow.

Today Robin Denny offers his second relief post.  Here are all the previous ones.

Clyde paddle-steamer Lucy Ashton operated from 1888 until 1949, at which time she was taken out of service and was about to be broken up.  But scrapping or reefing isn’t the only thing to do with an obsolete passenger vessel.

Step in the British Shipbuilding Research Association and Sir Maurice Denny.  They bought Lucy Ashton, had her paddles, paddle boxes and all upperworks stripped off and replaced by a large gantry on which were mounted four Rolls-Royce Derwent pure jet engines. Thrust gauges were fitted to measure exactly how much power was produced by the jets.   She ran various trials on the River Clyde and the Gairloch, an area familiar to some US veterans, at speeds up to 14 knots (in excess of??)    Indeed this is the world’s first jet powered vessel?

Inside this building is.

Here is the interior of the tank showing to the left stored test models, and in the center, the measuring instruments’ chariot with a test model beneath and the rails which rise by 15mm (5/8ths inch) at the half way point of 100 yards to follow the earth’s (and water) curvature!

​In 1949, Sir Maurice Denny, Chairman of the Dumbarton shipbuilders William Denny & Bros., was seeking to establish the accurate relationship between test figures for drag and resistance obtained in our Ship Model Test Tank and actual figures of ships in service.

Model testing was in still fresh-water with no turbulence from propellers or paddles. Dr. William Froude had produced accurate formulae to calculate the necessary adjustments but practical, full-size testing was very appealing.   In 1883 William Denny, with the help of Dr. Froude, built the first commercial test tank at 300′ x 30′ x 10′ depth.   It proved it’s worth immediately, especially in 1887 when we tendered to build two fast cross-Channel ships for the Belgian Government. The stringent contract stipulated a speed of 20 1/2 knots on trials with rejection of the ships if the speed was below 19 1/2knots. The test tank was vital. The tank tests could only confirm 19 1/2 knots, so the tank staff, contrary to received wisdom of the time, suggested INCREASING the beam, so achieving 21 1/2knots, making her the fastest ship in the world apart from skinny Naval torpedo boats.  The Belgian ships reduced the Dover-Ostend crossing from 4hrs.45mins. to 2hrs.55mins.

Many thanks to the cooperation of the Scottish Maritime Museum for assistance with these photos.

With that, I am grateful to Robin for telling me the story of the jet-powered former paddle steamer.   And I’m thinking it’s high time I get back to the UK.