River Class (1942) FF

The River Class (1942) were a new type of vessel for designed for ocean convoy protection. They were given the new classification of frigate. 

(Note: The term frigate had been used before during the sailing era. But the new frigates bore no resemblance to the old frigates. The old sailing frigates cruised the oceans and when sail was replaced by power, evolved into what became known as Cruisers during the powered era.) 

When WW2 started it was realised that the number of vessels available to provide protection to merchant vessels was utterly inadequate. There were a total of 51 escort vessels available plus another 62 building, against a requirement of about 700. The Black Swan Class (1939) fulfilled the requirements of an ocean escort vessel but were too complex and costly to put into large scale production. The Flower Class (1940) Corvettes were adequate for coastal protection duties and cheap/small/simple enough to put into large scale production and get hulls in the water. 

Unfortunately with the fall of France in 1940, German U-boats could be based in the Bay of Biscay and range far into the Atlantic. So convoy protection had to be provided much further out into the Ocean than previously envisaged. Realistically right across the Atlantic as long range U-boats increased in numbers. So the Corvettes were asked to perform way beyond their design limits.

The solution was the design of vessels with a length of 300ft, (the minimum for ocean work), powered by two sets of corvette machinery giving a speed of 20kts, a compromise against the requirement of 22kts. With a large range. The overall design was kept as simple as possible and mostly adopted merchant vessel construction practice. They were cheap and simple enough to produce in quantity, and adequate for ocean convoy protection.

The new convoy escort vessel type, frigate, was born.

In fact the class was initially called twin-screw corvettes, and the first few vessels allocated 'Flower' names. But the new category frigate was awarded while the early vessels were under construction.

The River Cass of Frigates were built in two groups. With a first group of 24, followed by a second group of 44. During construction  of the first group it was realised that greater range was needed and so the second group had their bunker capacity increased by 210 tons by using all available void spaces. This gave a 2,000nm increase in range from 7,500nm to 9,500nm.  

In addition large numbers were produced in Canada and Australia

The USA also produced all welded copies of the River Class to US standards. With 21 being transferred to the Royal Navy under lend/lease with the classification Colony Class (1942) FF

Armament was basic with a singe 4in gun forward and aft to provide all round fire against a surfaced submarine, light AA guns of 20mm, Hedgehog forward, and 8 mortars and twin racks aft for depth charges. 

However North Atlantic winter weather was considered in the design, with shelters provided for the 4in gun crews, a long fo'c'sle, bridge well back from the bows, and the forward 4in gun mounted as high as possible making it able to fight in almost all weathers.

They gained a reputation for seaworthiness.

During the war 6 were transferred to the Free French Navy, 5 to the Royal Canadian Navy (loaned), 5 to the Royal Indian Navy, 1 to the South African Navy (loaned), and 1 to the Royal Netherlands Navy.  


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This page last edited - 01 November, 2012.

Copyright Ian M King, except where otherwise indicated.