Coastal Motor Boats: Thornycroft and the Origins of Fast Attack Craft

280 pages

Chris O’Flaherty

This is one of the most elegantly and engagingly written naval histories currently in print; Kelly and Griffiths have scripted a masterpiece of original maritime research.

The Coastal Motor Boat, or CMB, was a deceptive name given to the very first generation of high-speed motor torpedo boat. Designed in 1915 to be embarked in Royal Navy cruisers using existing boat davits, and then launched close to enemy harbours to allow torpedo raids against our foes’ own backyards, their very existence was kept under the strictest secrecy.

This new and exciting volume starts by exploring the history and personalities behind the conception and early designs of CMBs. Centred around the Thornycroft family, the genesis of the design emerged from a peacetime penchant for small racing boats, enabled by the late 19th century development of high-speed petrol engines. One particular racing boat, Miranda IV, had taken the racing world by storm as Thornycroft’s 1910 design finally achieved consistent planning; the waterplane limitations of the semi-displacement hull had been overcome and new speed records were achievable.

When war broke out in 1914, motor racing enthusiasts saw the potential for these fast craft to be repurposed as raiders carrying torpedoes. A long series of tank tests settled on a 40-foot stepped hull design which went into series production in 1916, optimised for high-speed, surprise, in-out raiding of German ports. But senior officer scepticism (notably Admiral Jellico) cancelled that mission in favour of giving the new craft to Vice Admiral R Bacon (nickname ‘Streaky’!) for general patrolling off Dover.

Herein lies the first of many lessons that can be drawn from this superb book. Admiral Bacon employed these carefully optimised craft on a mission for which they were most certainly not designed, and their difficulties in conducting prolonged low speed patrols, due to a lack of onboard facilities such as heads, crew shelter or radio comms, served to accentuate early doubts about their utility.

The next evolution saw a production run of 70 55-foot designs, variously optimised across a range of patrolling, minelaying and anti-submarine missions. One especially notable innovation was a ‘spiral propeller’ (i.e. no blade tips) which successfully allowed selected CMBs to drive right over the top of underwater obstructions such as cables and nets, but with very minimal loss of propulsion efficiency or speed.

Whilst these CMBs saw some limited action towards the end of the Great War, occasionally raiding Zeebrugge and Ostend from a forward base in Dunkirk, it was not until 1919 that their opportunity to shine was emphatically seized by all involved.

In the stand-out section of the book, the examination of the 1919 CMB raids at Kronstadt is the most detailed this reviewer has encountered. A great deal of original research underpins the authors’ provocative assertion that “much of what was achieved relied on good luck … giving a short-term tactical superiority in the maritime war [but] did not, however, make any enduring strategic difference in the Baltic.” A combination of wardroom bravado, Nelsonian disregard for orders, and a sprinkling of la liaisons dangereuse for one young officer, all make for a compelling read of derring-do that justifies their analytic stance.

Overall, this book is an outstanding example of great scholarship written up as a thoroughly engaging historical narrative. For those among us who strive to turn good ideas into great outputs, it is a tale of innovation and endeavour. For historians, it expands the accessible record of the early history of fast naval craft. And for all readers, it is a wonderfully written education centred on a century-old dramatic era, together with its lasting effect on today’s naval forces. Highly recommended.