File:HMS Wild Goose (U45) Model.jpg

English: A model of the Black Swan Class Sloop HMS Wild Goose at the Glasgow Transport Museum, 2 March 2007.

The sloop was revived as a classification in WWI with the ocean-going Flower Class originally classed as minesweepers but which were more often used as convoy escorts, and the coastal P-Boats and PC-Boats originally classed as patrol boats but which were used as A/S vessels. After WWI no more sloops were built until the old ships needed replacing in the late 1920’s. The new ocean going sloops were designed for colonial service, patrol duties and minesweeping but as successive classes were built escort duties became more and more important. Destroyers were expensive ships that weren’t particularly suitable as A/S escorts in that ASDIC (US Sonar) did not work efficiently above 20 kts so the powerful machinery and 30+ kt speed of the destroyer was wasted; neither did destroyers, with their fuel-hungry engines, have the long range necessary for escorting convoys across the North Atlantic. The sloop, however, was the ideal basis for a long range escort.

The climax of inter-war sloop development was the Black Swan Class, a minor improvement on the preceding Egret Class of three ships built in 1938. The Black Swan class were multi-purpose A/S and AA escorts and minesweepers, though eventually the minesweeping gear was removed and the succeeding Modified Black Swan Class were A/S & AA escorts only. There wasn’t really a hard division between the two classes as improvements and modifications were steadily introduced almost ship-by-ship. Indeed, the last two Black Swans were hardly distinguishable from the Modified Black Swans.

Between 1939-42 13 Black Swans were launched, completed in 1939-43 and 24 Modified Black Swans were launched in 1942-46 and completed in 1943-46; 5 more of a further modified design were cancelled at the end of the war.

The original Black Swans measured 300 ft x 37.6 ft x 11 ft and had a displacement of 1,250-1,300 tons. Their 3,600 shp turbines and 2 screws gave them a speed of 19 kts. Their designed armament was 6x4” AA guns, 4x2 pdr AA pom poms (1x4) and either (first 6) 4x0.5” mg (1x4) or (second 6) 12x20 mm AA (6x2) and 40 depth charges (last two 60 depth charges) but this varied as the war progressed and 2x40mm AA guns were sometimes fitted (as shown on the model). In addition, depth charge stowage increased to 110.

The Modified Black Swans measured 300 ft x 38.6 ft x 11 ft and weighed 1,350 tons. Their 4,300 shp turbines gave a speed of 20 kts. As designed their armament was identical to the last 6 Black Swans except they had the capacity for 110 depth charges.

Efficient escorts though the sloops were, they were built to the Admiralty’s warship standards in yards that were familiar with the demands of warship construction whilst their turbines required specialist manufacture. The need for a mass production ocean escort was initially met by the small Flower Class corvettes (based on a commercial whaler) but there remained the need for a larger, more seaworthy, more capable escort and the result was the frigate, effectively a cross between the sloop and the corvette. It was the size of a sloop but instead of being built on high standard warship lines with precision-made turbines, was, like the Flowers, built on mercantile scantlings with unsophisticated reciprocating engines. They could be built cheaply and quickly in yards unfamiliar with warship construction. But they never displaced sloops entirely, so formidable as escorts were they.

HMS Wild Goose herself was built by Yarrow Shipbuilding, Scotstoun, Glasgow, being launched in 1942 and completed in 1943. She spent much of the war escorting North Atlantic convoys as part of Commander Johnnie Walker’s ace 2nd Escort Group of 6 Black Swans which sank 23 U-Boats in a two year period. A particularly famous exploit took place in early 1944 when Wild Goose and her sisters sank 6 submarines on one convoy escort mission in early 1944, 3 being sunk in 15 hours. After her service with 2nd Escort Group she was refitted and then served as part of a force to ward off U-Boat attacks on the invasion force during the Normandy landings. Between February and March 1945 she was deployed as part of the A/S force countering the last U-Boat offensive of the war around the coasts of Britain and she shared with a frigate the sinking of U-327 whilst she sunk U-683 on her own. She was then refitted for service with the Pacific Fleet but the war ended before she sailed. So highly regarded were the Black Swans and Modified Black Swans that all were allocated to the Eastern Fleet and Pacific Fleet after the war in Europe ended. Post war Wild Goose served in the Middle East before being scrapped in 1956.