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Marine Engines

Wednesday 27 June 2007, by Roy Gasson

The advent of the large Napier car engine in the UK was also to further the sport of Powerboat Racing internationally. S F Edge applied his competitive spirit to the water using a series of “Napier” named boats to win trophies for Great Britain around our shores, in Europe and the USA. The 4 cylinder Napier marine motor in 1905 was produced and demonstrated in sizes between 20 and 75 bhp both singly and in multiple giving installations up to 300 bhp.

Boats with names like: Napier II and Napier Major were used in 1905 by Edge to gain 18 first place awards for D Napier & Son engines. The Napier Major fitted with a 20 hp engine in the 1905 reliability trials covered 219 miles in 10 hours, gaining the best all-British boat award in her class. By contrast the Yarrow built “Napier II” racer, with a pair of 72 bhp motors won the British International Cup (Harmsworth Trophy), scored 14 other first places and set the world water mile record at 29.9 mph.

Naval interest in the high-speed launch was aroused in 1906 when a 60foot Yarrow-Napier Motor Torpedo Boat was tested at 25.5 knots. Fitted with 5 Napier engines, each of 75 bhp, she was the forerunner of many such future naval craft.

It was the supercharged Napier “Lion” aero engine that was chosen by Hubert Scott-Paine for his racing hydroplane boat “Miss Britain III” taking the world water mile record to over 100 mph in 1930. For the armed services in the 1930’s he designed the British Power Boat Co. built fast patrol boats powered by triple 500 bhp “Sealion” engines capable of 35 knots laden. These light MTB’s for the Royal Navy and fast Air-Sea Rescue Launches for the RAF both provided vital coastal support during WW2 and on into the 1950’s.

It was Napier’s own marine “Deltic” 2 stroke diesel engines, designed before 1950, that provided power for the next generation of FPB’s, the Saunders-Roe “Dark” class for the RN and then the 47 knot Norwegian Navy “Nasty” class used worldwide with 2 turbocharged “Deltics” of 3100 bhp. Today the RN inshore minesweeper fleet and fisheries protection vessels are fitted with 9 cylinder “Deltic” power plants.

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2 Forum messages

  • Marine Engines

    8 October 2013 17:27, by Uriel Uzdil - Brussels

    Dear Sirs, I intend to build a model of the Napier Lion VIID for my Miss Britain III model. I have a VIIB drawing with dimensions for the block, and a VIID side view without dimensions. Can you please help me find the VIID drawings with dimensions, or at least a Supercharger end view?

    KInd regards, Uriel Uzdil

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    • Marine Engines 9 October 2013 06:03, by Roy Gasson

      Dear Uriel, Yes we do have a dimensioned front on cross section, and a side on dimensioned cross section. At a cost 5. 00, the two plus post and packing. Please contact

      Best regards
      Roy Gasson
      Site administrator

      Reply to this message

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