Thread by @nicholadrummond

A THREAD ON CORVETTES
At the beginning of the Second World War, the Royal Navy had 332 warships making it the world’s largest navy. The fleet included 15 battleships, 7 aircraft carriers, 66 cruisers, 184 destroyers, 45 patrol vessels, and 60 submarines.

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While the size of the Royal Navy’s fleet was a major factor in deterring Hitler’s invasion plans, it was not properly equipped to fight the Battle of the Atlantic. This required a new kind of ship to counter the menace of Germany’s U-boats.

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The requirement called for a vessel able to detect and destroy submarines. It had to be small and inexpensive so it could be produced in large numbers. And it needed be easy to operate, so it could be crewed by inexperienced sailors.

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The result was the Flower Class corvette. The design was based on a whale-catcher. It displaced 940 tonnes, was 62.5 metres in length, and had a crew of 85. A 2,050 Kw steam engine gave it a range of 3,500 Nm (6,482 km) and a top speed of 16 knots (29.6 kph).

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Flower Class corvettes mounted a Mk IX 4” naval gun, four Mk II depth charge dispensers and twin .303 Lewis guns. Ships were later modified so that they additionally had a 40mm “pompom” anti-aircraft gun, two Oerlikon 20mm cannons, and Hedgehog anti-submarine mortars.

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Submarines were detected using ASDIC sonars in domes fixed to the hull. Refitted ships added a surface radar mounted in a lantern housing behind the bridge. Although slow, Flower Class vessels were faster than submerged submarines, which averaged around 8 knots.

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Flower Class corvettes were unsophsitcated, even by 1940 naval standards, but nevertheless did an excellent job escorting vital convoys across the Atlantic. A total of 267 were built between 1939 and 1940 and were operated by British, Canadian, French and US navies.

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During the course of WW2, 36 Flower Class corvettes were lost, of which 22 were torpedoed by enemy U-boats. They accounted for 51 enemy submarines sunk (including 47 German plus 4 Italian boats) and represented almost 50% of total allied escort vessels during WW2.

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The contribution made by Flower Class corvettes was graphically depicted by the 1952 war film “The Cruel Sea” starring Jack Hawkins and Denholm Elliott. Based on the the novel of the same name by Nicholas Monsarrat, it ranks among the top British war movies.

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The Royal Navy’s WW2 cruisers and destroyers were much more potent and capable warships, but the Flower Class played their part. Through critical mass, they saved countless lives, millions of tonnes of shipping, and prevented Britain from being starved into surrender.

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Today, Britain has the 5th largest navy behind the USA, Russia, China, and Japan. It currently possesses 74 vessels including 2 aircraft carriers, 6 destroyers, 13 frigates, 11 submarines, 2 commando assault ships, 13 MCM vessels, 22 patrol boats and 5 survey ships.

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Although today’s warships are much better equipped than their forbears, 19 surface combatants is an extremely low number to fulfil all the roles essential to the United Kingdom’s defence and security. In terms of critical mass, the Royal Navy may now be too small.

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With a vastly increased naval threat posed by Russia and China, a major conflict would require Britain to address the same problem it faced at the beginning of WW2: a shortage of ships capable of detecting and destroying submarines.

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Fortunately, a contemporary version of Flower Class ships already exists. This is advanced corvette designs developed by several by NATO shipyards. Typically, they displace 3,000 tonnes, have two 7,000 Kw engines, a top speed of 30 knots and a range of 3,500 Nm.

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Modular by design, modern corvettes can be equipped with 76mm main guns, vertical launch cells for AA, ASROC and S2S missiles, CIWS for point defence, cannons and ASW helicopters. Bow mounted sonars, towed arrays and powerful radars help them track and kill targets.

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With a unit price of €250 million, versus almost €1 billion for complex anti-submarine frigates, like FREMM or Type 26, a critical advantage of modern corvettes is affordability. UK shipyards would be able to build them quickly and easily, just as they did in WW2.

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A large part of the cost is not the ship itself, but the weapons, sensors and other systems that make it credible. Things like Artisan radar, towed sonar arrays, Sea Ceptor AA missiles, Harpoon anti-shipping missiles, and CIWS are what most add cost.

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Ultimately, a new class of corvettes would need to balance affordability with effectiveness. It wouldn’t be the same as having a WW2 fleet of 500 surface combatants, but 20 contemporary Flower Class vessels would do much to enhance the Royal Navy.

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