Banff-class sloop, HMS Sennen (Y21) (1945)

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Banff-class sloop, HMS Sennen (Y21) (1945)


Design and service history:

The Banff-class sloop was a group of ten warships of the Royal Navy, initially built as United States Coast Guard Lake-class cutters, which where loaned to the royal navy in 1941 as part of lend lease in order to serve as antisubmarine warfare escort ships. These transfers took place at the Brooklyn Navy Yard; with the sloops being manned for transport to Britian by personnel from the damaged battleship Malaya which was under repair there. The Sloops initially served of parts of the Western Approaches command for use in convoy escorts, such as the SL convoys from Sierra Leone to Liverpool. The US Coastguard Cutter Champlain was initially built by Bethlehem Shipbuilding, Quincy, Mass, with the ship laid down in the 23rd of may 1923, and launched on the 11th of october 1928, with ultimate build being completed on the 24th of january 1929. The ship was renamed HMS Sennen upon entering service with the Royal navy, being the first ship to bear this name, that of a british coastguard station, in this case Sennen in west cornwall.

Initially poorly armed Sennen, escorted convoy HX 139 to london in July of 1941, at which point she was selected for refit, which would take place in early august, in which she was equipt with antisubmarine equiptment including depth charge launchers and two sets of rails. After this refit she rejoined the western approaches based at londonderry, along with her sister ships, though she would undergo another refit in october in dublin to aquire more antisubmarine equiptment including a hedgehog launcher. After this she would commonly be paired with HMS Gorleston, Hartland and Totland to escort ships to and from Sierra Leone, with a brief stop over in london on the 4th of may 1942 to allow a Type 271 for surface warning and Type 286M radar to be fitted which would last until the 29th of june, after which she returned to her normal role of convoy escort along the african coast. This role would change with the start of operation torch, and HMS Sennen would be used for convoy defence in the Mediterranean, escorting shipping to and from Gibraltar before being reassigned to convoy escort in the North atlantic in Febuary of 1943 in order to help counter the u-boat wolf packs preying on shipping crossing the pond.

It was during this assignement that she claimed her first submarine action when after ineffectually firing on U-267 on the 6th of may 1943, with the boat managing to slip away undamaged. This lack of luck would not stick, and 19th of may she took part in the sinking of U-954, with the support of the frigate HMS Jed in defense of a convoy. The submarine was lost with all hands, among which was leutnant Zur Zee Peter Donitz, son of Grosssadmiral Karl Donitz. This feat would be repeated on the 20th of june, when she and HMS Jed again came under submarine attack, when they charged the surfaced U-209, which fired its torpedos at them and tried to flee, only to get chased down and eliminated by the hedgehog launcher mounted on HMS Sennen. After these successes, Sennen underwent another refit and was reassigned to convoy duties in the indian ocean, where she would serve without incident, with the only distinguishing thing being some awards being granted for assistance in the salvage of equipment from U852 abandoned at Bandar Beila, Somaliland in May of 1944. In october of 1944 she was ordered to capetown for refit, in which she recieved a British 4in mounting and additional 40mm weapons were fitted to improve close range defence for a possible assignement to the pacific front in order to support proposed beach landings in japanese occupied malaya. This would prove unessassary though, as by the time the refit was complete in mid april of 1945 the war was already winding down, with the ship being assigned to Trincomalee to be assigned to convoy defense in the bay of bengal. With the war coming to a close she completed a convoy escort assigment to the dutch east indies, remaining in the pacific until the 16th of december 1945, at which point she returned to the uk via aden. The ship arriving safely at Chatham on the 16th of January 1946, and after completion of repair, she undertook passage to boston to be returned to us coastguard service. She was paid off at boston on the 20th of march, and was returned to USCG service that year again under the name USS Champlain, with the ship ultimately being sold for scrapping on the 25th of march 1948.

Ship Specification:

Displacement:1,546 long tons (1,571 t; 1,732 short tons)

Length: 250 ft (76.20 m) o/a

Beam:42 ft (12.80 m)

Draught: 16 ft (4.88 m)

Propulsion: Two oil-fueled Babcock & Wilcox boilers, Curtis turbine generator, Single shaft electric motor producing 3,200 ihp (2,400 kW)

Speed: 16 knots (29.6 km/h,18.4125 mp/h )

Range: 7,542 nautical miles (13,968 km) at 12 knots (22.2 km/h)

Complement: 97

Armament: 1 x QF 4-inch naval gun Mk V

1 × QF 12-pounder 12 cwt naval gun on a MK.5 mount

2 x QF 2-pounder naval gun “Pom Pom” in Mark VIII mounts

6 × single Oerlikon 20 mm cannons

16 x depthcharges in two 8 charge racks and four Throwers

1 x Hedgehog launcher

Additional Historical Pictures:

Photo showing HMS Sennen early in her service, with a limited armament:

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Photo showing HMS Sennen in Poole Bay passing HMCS TRENTONIAN, 5 June 1944:

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