"Minesweeping of course comes almost naturally to the fishermen who man the trawlers. The task of handling and towing the minesweepers is almost the same thing as their ordinary occupation of handling the trawl."

At the out break of war trawler production was gradually increased to meet the need for suitable AS (anti-submarrine) and minesweeping vessels. An increasing amount of mercantile trawlers were also requisitioned and fitted out for war. These included Arctic whalers and the wooden constructed drifters first used during the World War 1. The tough and enduring sea worthiness of the trawler was seen to be an ideal choice for an escort vessel. This enabled the vessel to deployed in the roughest of seas which would often even force a larger ship such as a destroyer to seek shelter.

Naval trawlers were produced mostly during the course of WW2 as number of small shipyards specialised in this type of ship and their resources were idealy suited to the Admiralty. The order was given for the construction of new trawlers based on the commercial designs which could be readily modified into escorts and minesweepers.

Armament
The main armament to be fitted, usually corresponded to a vessel's particular duty or task. The larger and faster trawlers and whalers were fitted out as A/S and armed with a 4-inch gun and the older vessels as minesweepers and patrol craft armed with a 12 pounder. This also applied to most requisitioned craft although at first, some had to make do with a much smaller and less effective vintage 3-pounder or 6-pounder gun.

Generally to transform a trawler into a man-of-war, a considerable amount of modification had to be carried out. To carry the guns hull frames and deck beams had to be strengthened. At the front of the ship on the forecastle, and on situated on the whaleback a 12 pounder or 4 inch was mounted and aft (or rear) of the funnel a purpose built mounting was fitted to hold a Oerlikon, Bofors or a pair of five-inch machine guns. For the added protection against air attack, Lewis or Hotchkiss guns were fitted in the bridge wings. For vessels destined for A/S work depth-charge throwers and rails would also be fitted along with the necessary Asdic equipment for detecting enemy submarines.

Conditions on board a fighting trawler
Alterations to a trawler's basic design were also carried out in order to accommodate a larger crew, (usually around 30 or so for the average A/S trawler including at least two skippers). The fish-hold became the main ship's company mess deck with wooden mess tables and stools. Above in this confined and cramped area, hung hammocks on special hooks on the beams in any available space. Sometimes the Stokers (often nicknamed the black gang), had a separate mess. Usually below the mess deck and in a specially constructed magazine, was stored the amimunition for the ship's guns. The officer's quarters were situated below the wheelhouse and contained a couple of bunks along with some basic furniture, a cuboard and a safe for confidential books etc. Lastly a small galley was included, where one Cook had the impossible task of keeping an entire crew happy with the sparsest of wartime provisions.

At sea these cramped conditions were anything but ideal and in a heavy storm they could soon become very uncomfortable. This was particulary hard on those men who had not been part of the peacetime fishing fleet and therefore had no previous experience of life at sea. A Small ship such as a trawler will always ride the waves rather than push a path through them like a larger vessel. As a result the pitch and roll of a small ship in a heavy swell will make the most simplest of tasks almost impossible.