Flower class corvette

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USS Intensity
USS Intensity (ex-HMS Milfoil), in 1943.
Royal Navy Ensign General characteristics
Displacement: 940 tons (980 tons revised)
Length: 205 ft (208 ft revised)
Beam: 33 ft
Draught: 11.5 ft
Propulsion: 2 fire tube boilers, one 4-cycle triple-expansion steam engine
Speed: 16 knots at 2,750 hp
Range: 3,500 nautical miles at 12 knots (6,500 km at 22 km/h)
Complement: 85 men (revised - 109 men )
Armament: 1939–1941


Revised 1941–1944

The Flower class corvettes were a class of 267 corvettes developed by the Royal Navy and Royal Canadian Navy specifically for the protection of shipping convoys during the Battle of the Atlantic (1939-1945) in World War II. They were a stop-gap measure in the war against the German U-boats: small ships that could be produced quickly and cheaply in large numbers. Despite being initially intended for coastal convoys, their long range meant that they became the mainstay of convoy protection in the first half of the war. After the war the Flowers were sold off and served around the world from the Israeli Navy to the Chilean Navy.

The name "corvette" originally referred to the 19th century sloop-of-war, a small screw warship with a similar shipping-protection role.

There are two different vessels in the Flower class. The first vessels from the 1939 and 1940 programmes were followed by another 64 ships launched from 1940 onwards which were slightly larger and better armed; this subclass is sometimes called the "revised Flower class". The revised Flowers of the United States Navy are also known as Action-class gunboats with the "PG" hull classification symbol.

Contents

[edit] Design and construction

The design of the Flower class was derived from that of a whale catcher, the Southern Pride of Smiths Dock Company of Middlesbrough. Originally intended for coastal convoy protection, nevertheless they soon found themselves in the role of ocean escort. They were a stop-gap measure to take the strain of convoy protection until large numbers of larger vessels — destroyers and frigates — could be produced. Their simple design using parts common to merchant shipping meant they could be constructed in small commercial shipyards all over the United Kingdom and eastern Canada where larger ships like destroyers could not be built. Additionally, the use of commercial machinery meant that the largely reserve and volunteer crews that manned them were familiar with their operation.

Corvettes were slow and lightly armed, intended solely for anti-submarine warfare (though many Canadian Flowers were adapted for minesweeping and the revised Flowers had limited anti-aircraft capability).

The early Flowers had the standard Royal Navy layout of a raised forecastle, a well deck then the bridge and a continuous deck running aft. Later Flowers had the forecastle extended aft past the bridge to the aft end of the funnel, a variation that was known as the "long forecastle" design. Apart from providing a very useful space where the whole crew could gather out of the weather, the added weight improved the ships' stability and speed and was retrospectively applied to a number of the earlier build.

Originally the mast was immediately in front of the bridge, a notable exception to naval practice. It was moved in the long forecastle types to the normal position of immediately behind the bridge, however this does not seem to have been done in all of the conversions. A cruiser stern finished the appearance.

The United Kingdom built 145 Flower class corvettes from 1939. A large number (120 reported by one source) were also built by Canadian shipyards. The Canadian design had detail variations. Canadian Flowers had the bandstand, where the aft pom-pom gun was mounted moved to the rear of the superstructure. And they had the galley moved somewhat forward to just abaft the engine room.

[edit] Corvette armament

The original corvette design provided for a naval 4" gun on the bow, ASDIC, depth charge racks carrying 40 charges on the stern, a minesweeping winch and a 2-pounder pom-pom on a bandstand over the engine room.

Due to initial shortages a pair of Lewis guns was sometimes substituted for the pom-pom, which would have left the ship very vulnerable to aircraft attack in its envisaged role of North Sea patrol. However, fighter-bombers were rarely encountered on Atlantic duty. Mediteranean ships usually had uprated anti-aircraft capability.

Detection capability included a fixed ASDIC dome (later retractable) and a High Frequency radio Detection Finder (Huff-Duff). Later the type 271 radar was added, which proved particularly effective in low-visibility Atlantic actions.

Though originally designed for inshore patrol and harbour anti-submarine defence, the Flowers were deployed as Atlantic escorts, and were modified as required for this service. Since the ships were able to be supported by any small dockyard, individual ships would have had a variety of different weapons and design fits at different times, depending on when and where they refitted, and there is really no such thing as a 'standard Flower'. A few of the major changes which many ships underwent are indicated below, in a typical chronological order:

  • Original twin mast configuration changed to single mast in front of bridge, then moved behind bridge for better visibility.
  • Minesweeping gear removed.
  • Galley resited from stern to midships.
  • Extra depth-charge storage racks fitted at stern. Later more depth-charges stored along walkways.
  • Two or four spigot mortar depth-charge projectors fitted to enable remote attacks while keeping ASDIC contact.
  • Radar fitted in 'lantern' housing on bridge.
  • Forecastle lengthened to midships to provide more accommodation and better seaworthiness. Several were given a 'three-quarters' length extension.
  • Various changes to the bridge, typically lowering and lengthening it. Enclosed compass house removed.
  • Extra twin Lewis guns mounted on bridge or engine room roof.
  • Oerlikon 20mm cannons fitted - usually two on bridge wings but sometimes as many as six spread out along engine-room roof, depending on theatre of operations.
  • 'Hedgehog' forward depth-charge projector fitted.

Note that any particular ship may have had any mix of these (including none), in any order, or other specialist one-off modifications. Ships allocated to other navies such as Canada or the US would have had different armament and deck layouts again, making this class one of the most variable in the RN.


[edit] Operation

Flowers were used extensively by the Royal Navy and the Royal Canadian Navy during the Battle of the Atlantic (1939-1945) and elsewhere. Many were constructed for or transferred to other navies, including the Royal Netherlands Navy, the Royal Hellenic Navy, the Free French and French Navy, the Royal Norwegian Navy, the Indian Navy and United States Navy during and after the war.

The Royal Navy Flower-class corvettes were officered and crewed by members of the Royal Naval Reserve and the Royal Navy Volunteer Reserve (RNVR). The captains were largely from the merchant navy.

Service on corvettes was cold, wet, monotonous and uncomfortable. The ships were nicknamed "the pekingese of the ocean". They had a reputation of being very bad at rolling in heavy seas, with 80-degree rolls (that is, 40 degrees each side of the normal upright position) being fairly common - according to Nicholas Monsarrat they "would roll on wet grass" - however, they were very seaworthy ships.

Flower corvettes provided the main escort duties during the critical Battle of the Atlantic, and so were in the thick of the fight. Their primary aim was to ensure that merchantmen survived the crossing rather than sink U-boats, and so if a convoy encountered a U-boat a typical action would involve the corvette forcing the submarine to dive (thus limiting its speed and manoeverability) and keeping it underwater (and pre-occupied with avoiding depth charge attack) long enough for the convey to pass unmolested. This tactic was stretched to the limits when the U-boats made a 'wolf-pack' attack, intended to swamp the convoy's defences, and the Flower's low top speed made effective pursuit of a surfaced U-boat impossible.

Radar, Huff-Duff radio direction finding, depth-charge projectors and ASDIC meant that the Flower was well equipped to detect and defend, but lack of speed meant that they were not so capable of joining the more glamorous fast hunter-killer surface groups which were in place by the end of the war. Success for a Flower, therefore, should be measured in terms of tonnage protected rather than U-Boats sunk. Typical reports of convoy actions by these craft include numerous instances of U-Boat detection near a convoy, short engagement with gun or depth-charge, followed by a rapid return to station as another U-Boat takes advantage of the fight to attack the unguarded convoy. Continuous actions of this kind against a numerically superior U-Boat pack demanded considerable seamanship skills from all concerned, and were very wearing on the crew.

35 were lost at sea, of which 22 were torpedoed by U-boats, and 4 sunk by mines. It is thought that Flowers participated in the sinking of 47 U-boats and 4 Italian submarines. (Tables of both sets of sinkings appear below.)

Construction of Flower-class corvettes was superseded toward the end of the war; larger shipyards concentrated on River-class frigates and smaller yards on the improved Castle class corvettes. However, nearly half of the Allied escort vessels belonged to the Flower class.

[edit] German Flowers

Four Flower-class corvettes under construction for the French Navy at Saint-Nazaire were captured by Germany after the battle of France. Construction was continued and they were launched in 1943–1944 as PA-1 to PA-4. One was sunk as a blockship and the other three were put out of action or sunk by Allied bombing.

[edit] After the war

Corvettes were among the first ships to be sold or scrapped after the war. The Flowers had seen years of hard service in the Atlantic and had been made obsolete by the larger frigates and destroyers. 32 were sold on to the navies of Chile, the Dominican Republic, Greece, India, the Republic of Ireland, South Africa, and Venezuela where some served, typically as coastal patrol vessels, until the 1970s.

110 went into commercial use as freighters, smugglers, tugs, weather ships, and whalers. The remainder were scrapped. Of particular interest is the story of HMCS Sudbury, built in Ontario in 1941. After WW2 ended she was converted to a towboat and Harold Elworthy, owner of Island Tug & Barge bought her in 1954. The Sudbury and her crew specialized in deep-sea salvage and completed many dramatic operations, but made their reputation in November/December 1955 when they pulled off the daring North Pacific rescue of the Greek freighter Makedonia.

The Sudbury towed the disabled vessel for 40 days through some of the roughest weather imaginable before arriving safely into Vancouver to a hero's welcome. The incident made headlines around the world and for the next decade the Sudbury and her 65-meter sister ship Sudbury II, purchased by Island Tug in 1958 were the most famous tugs on the Pacific coast.

Two Canadian Flowers that had been sold as freighters were bought in 1946 by the Mossad Le'Aliya bet, a Jewish organization in Quebec that smuggled Jewish survivors of the Holocaust into Palestine. The corvettes sailed in the summer of 1946 but were intercepted by the destroyer HMS Venus and they and their passengers were interned in Palestine. After Israel became independent in 1948 these ships were commissioned into the Israeli Navy as Hashomer ("guard") and Hagana ("defence").

The Flowers were disposed of so quickly that in 1950 the Royal Navy could not supply one to play Compass Rose in the film of Nicholas Monsarrat's novel The Cruel Sea. Kriezis of the Royal Hellenic Navy (formerly HMS Coreopsis) played the role before she too was scrapped.

The only known surviving Flower, HMCS Sackville, has been restored to her wartime appearance, and is now a museum ship in Halifax, Nova Scotia, one of the ports where Atlantic convoys assembled during the war.

[edit] Literature

Life in corvettes has been recorded by several authors. Nicholas Monsarrat wrote a well-known fictionalised account in his novel The Cruel Sea which was filmed starring Jack Hawkins. Three Corvettes, a less well known volume by the same author is a collection of wartime essays of his personal experiences as a corvette officer although only the first part deals with Atlantic convoys.

Escort by Derek Rayner is another first-hand account. Notable for being written by an officer who served afloat and in command almost throughout the war.

The Corvette Navy by James B. Lamb is a fine account of the Royal Canadian Navy in World War II.

Yankee R N by Alex H. Cherry. Being The Story Of A Wall Street Banker Who Volunteered For Active Duty In The Royal Navy.

Storm Below by Hugh Garner (Toronto, 1949, William Collins and Sons) The first published novel by Garner, who served on corvettes in the Royal Canadian Navy in the Second World War. Detailed account of the ship and the stresses of shipboard life.

[edit] Ships

See List of Flower class corvettes

[edit] Flowers sunk by U-boats

[edit] Submarines sunk, destroyed, or captured by Flowers

[edit] See also

[edit] External links

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