After the loss of the experimental all aluminium MTB P1602 in early 1952, Saunders-Roe won the contract to detail design and build the next generation of FPB known as the Dark Class. They were somewhat ‘chunkier’ and box-like around the rear quarters than the more elegant P1602. The Darks were of a composite hull construction using riveted aluminium alloy frames and stringers over-clad with laminated timber strip planking. There were bolted to the metal frames and the decks were plated with riveted aluminium sheeting. They were powered by two Napier Deltic 18 cylinder 2-stroke supercharged diesel engines of 2,500 BHP each. Saunders Roe built Dark Adventurer, Aggressor, Antagonist, Biter and Avenger. During the building of these five vessels SARO shopped out components to other shipyards for the building of the rest of the series for the Royal Navy. The last that SARO build for the Navy was a variant on the design in the form of P1120 Dark Scout. She was the only all-welded aluminium Dark and was somewhat simplified by the looks of her. No doubt it was a cost cutting exercise to appease the Government as the remainder of the order for the Darks was about to be cancelled.
SARO also won a contract to supply two very similar vessels to Finland, Vasama 1 and Vasama 2. There appear to have been of conventional composite hull construction.
The Burmese Government also ordered a set of five all riveted aluminium clad FPB’s complete with a bespoke auxiliary battery-electric ‘slow-speed drive’. My father said it was for silently creeping up the many river creeks to search out pirates, smugglers, bandits and gun-runners – all exciting stuff for a youngster to hear! The aluminium hulls were specified to withstand marine worm attack that would have been a problem in the warmer tropical waters.
Following this series was one for Japan, service number PT9. There is a strange rumour that she was supplied with only one of the usual two Napier Deltic engines. It seems a strange tale and I can’t imagine why anyone would want to spread it. If the Japanese wanted a Deltic engine for some other purpose I would have though they could have obtained one by a less devious and expensive route. The company magazine article does mention two engines, so the rumour may be just that.
On the subject of tales and rumours there is a 1951 Saunders-Roe advertisement that illustrates P1602 and proudly proclaims she is the World’s First Aluminium Alloy MTB. This has been found to be untrue/incorrect. The Americans has an alloy MTB No PT-8 in 1934 and is today restored and for sale for around $1.4M
Long before PT-9 was a pair of aluminium hulled steam torpedo boats built by the Scottish Yarrow Co., one for France, Le Fourde in 1894 and a larger one for Russia, Sokol (Falcon) in 1895.
P1602 may be more accurately described as either Britain’s or the Royal Navy’s first aluminium MTB, unless that is proved incorrect? [click to enlarge]
- Rare colour photo of P1101 Dark Adventurer (possibly after running into Beaumaris Pier by her scruffy condition!)
- Launching of P1101 Dark Adventurer