Sloops and Escort Vessels

  During WW1 a specialised escort vessel was introduced to counter the threats posed by mine and submarine warfare against Trade.

Before then, no specialised vessels had been used for minesweeping or anti-submarine duties. 

Instead, destroyers were considered to be the most effective anti-submarine vessels, and trawlers had been requisitioned in large numbers as makeshift minesweepers and patrol vessels. 

As destroyers increased in size and cost, their numbers reduced. They also had to provide fleet protection so relatively few were available for convoy escort. In addition, Asdic (Sonar) could not be operated at speeds in excess of 20 knots so the destroyers speed was useless during the hunt and attack phases of anti-submarine work.

Trawlers were relatively slow when used as escorts and not quite shallow enough when used for inshore minesweeping duty.

So there was an urgent requirement for a specialised vessel of lower cost and lower manpower than a destroyer. While having greater speed and shallower draught than trawlers.

The new class of vessels were designated Sloops.

By the end of WW1 they had fallen into three distinct groups.
A) The Convoy Sloop with a large radius of action for ocean escort work. (Flower Class.)
B) The Patrol Sloop with reduced radius of action for coastal escort work. (P- and PC- boats.)
C) Minesweepers with the prime requirement of shallow draught. (Hunt Class.)

WW1 ended with large numbers of these vessels available. They were rapidly reduced with the post-war economies.

Between WW1 and WW2 the limited budget placed sloops low in the order of priorities, as against Fleet vessels.

In 1937 the term Sloop was officially dropped, but it continued in unofficial use, for some time. (although it continued in unofficial use, both in practice and literature. See the Classic book 'The Cruel Sea'.)

Escort sloops became Escort vessels.
Patrol sloops became Patrol vessels.
Minesweeping sloops became Minesweepers.

So when WW2 began the number of sloops available were;
A) Escort vessels, 40 plus 6 building.
B) Patrol vessels, 11 plus 56 building.
C) Minesweeping, 44 plus 20 building.

A total of 95 vessels.

War requirement for convoy escort was considered to be about 700 vessels.

The following table shows the authorised war construction numbers for convoy escorts.  


Where built Sloops Corvettes and Frigates Totals
Black Swan Flower River Loch/Bay Castle
Projected 36 300 168 113 96 713
British Built            
Reciprocating   145 51 53 44 293
Turbine 32   6 2   40
Cancelled 4 19   58 15 96
Canadian Built            
Reciprocating   124 70     194
Cancelled   6 19   37 62
Australian Built     12     12
Cancelled     10     10
French Built   4       4
Cancelled   2       2
Totals 36 300 168 113 96 713
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This page last edited - 26 April, 2013.

Copyright Ian M King, except where otherwise indicated.