BYMS 2026.  Mines exploding as British Yard Minesweepers were sweeping off the landing beaches for the invasion of Southern France.  Clearing the way for the invading force as it went in to the beaches. 

BYMS 2026 at Venice, Italy, next to her sister ship, the 2009. From the collection of Victor Gatherum.

BYMS 2026
British Yard Mine Sweeper


BYMS’s were built in the United States and transferred the Royal Navy under the Lend-lease Programme. “British Yard Mine Sweepers” are so called because they were built to the same design as the US Navy’s “Yard Mine Sweepers”.

Crews for the BYMS’s would sail to the United States, often on the Queen Mary, which could sail unescorted because of her greater speed, to collect their vessel. They would then have the formidable task of sailing their small vessel back across the Atlantic Ocean, often in winter. 

Following WW2, BYMS 2026 had an illustrious career. Renamed Calypso she was used as a ferry between Malta and Gozo. Calypso was bought by millionaire Thomas Guinness in July 1950 and leased to Jacques Cousteau for one franc a year. Jacques Cousteau helped to develop the SCUBA or Self-Contained Underwater Breathing Apparatus, the Aqua lung.

Jacques Cousteau converted the Calypso (formally BYMS 2026) into a, oceanographic research vessel and made some of the earliest underwater films and the long running TV series, the Undersea World of Jaques Cousteau. 

On the 8 January 1996 the Calypso was hit by a barge at Singapore and sank. She was re-floated and towed to Marseille, France.

At present the Calypso is being restored by the Cousteau Society, although there have been long running problems in doing so.

MINE SWEEPING FLOTILLA:  153rd MFS Mediterranean: 2009, 2019, 2022, 2026, 2027, 2037, 2077, 2171, 2172.

Built by: Ballard Marine Railway Co., Inc., Seattle, Washington, USA. (West Coast)
Laid down: 12 August 1941.
Launched:  21 March 1942
Handed over to Royal Navy: Great Britain 22 August 1942.
Laid up in Malta 1946.
Returned to USA: 1 August 1947
Sold to Joseph Gasan, re-named as Calypso and operated as a ferry between Malta and Gozo.


Wooden hull. Length, 130 feet. Beam, 25 feet 6 inches. Depth, 12 feet I inch. Draft, 8 foot 10.5 inches. Displacement 207-215 tons.

Engine: Two 800 bhp General Motors diesel engines.

Speed: 14.6 knots. 10 knots while sweeping. (Eight knots with double Oropesa sweeps)

Range: 2,500 at ten knots.

Compliment: 3 officers and 27 men.

Armament: One 3-inch HA/LA gun and two Oerlikon anti-aircraft guns.

BYMS’s were fitted with a drum on the stern with LL (double L) cables for sweeping magnetic mines, an acustic hammer on the bow for sweeping acustic mines and Oropesa floats for sweeping tethered mines.
All YMS and BYMS were built to the same design, the only variation was in the number of exhaust stacks. Minesweepers 1 to 134 had two sacks, 135 to 480 had one stack, 466 to 479 had no stacks.

Tempy. Lieut., R. S. Grieve 7 Apr 42
Tempy. Lieut., J. J. Butters (act) June 42.

Nothing on Navy Lists.

Tempy. Sub-Lieut., H. E. Robson 1 Apr 45
If you, your father or your grandfather have any additional information about this ship, crew lists, stories, photographs, please send copies of them to be added to our records and this website.

Thank you.


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22 August 1942, completed.
28 Feb 43, Seattle, USA (West Coast)
5 March 1943, San Francisco, USA.
23 March, Cristobal, Panama Canal.
19 April 1943, Belem, Brazil.
13 to 25 April 43, Freetown, Sierra Leone, West Africa.
13 to 23 June 1943, Gibraltar.
18 June to 15 Aug 1943, Malta.
26 Aug 1943, Augusta, Sicily.
9 Nov 1943, Malta.
17 March 1944, Malta.
13 April 1944, Messina, Sicily.
23 and 24 April 1944, , Augusta, Sicily>
24 May to 9 July 1944, Malta.
10 July 1944, Naples, Italy.
1 August o 3 Sep 1944, Naples, Italy.
25 Sep 1944, Bari, Italy, Adriatic Coast.
7 Nov 1944, Ancona, Italy, Adriatic Coast.
23 Dec 1944, Bari, Italy, Adriatic Coast.
30 Dec 1944, Corfu.
2 and 3 Jan 1945, Patras, Greece.
28 Jan 1945, Piraeus, Greece.
28 to 30 Jan 1945, Taranto, Italy.
11 Feb 1945, Bari, Italy, (Adriatic Sea)
9 to 14 March 1945, Malta.
16 March to 7 April 1945, Bari, Italy, (Adriatic Sea)
8 to 10 April 1945, Ancona, Italy (Adriatic Sea)
25 April to 6 May 1945, Ancona, Italy (Adriatic Sea)
9 May 1945, Trieste, Italy.
11 May 1945, Trieste, Italy.
19 May 1945, Ancona, Italy (Adriatic Sea)
1 June 1945, Ancona, Italy (Adriatic Sea)
28 July to 2 Aug 1945, Ancona, Italy (Adriatic Sea)
8 Aug 1945, Ancona, Italy (Adriatic Sea)

1 August 1947, returned to USA.

Thursday, 2026 October 1944. BYMS.2006, lost overboard.
CLAXTON, Leonard, Ty/Act/Skipper Lieutenant, RNR, killed.

BYMS 2026 after being converted into Jacques Cousteau's oceanographic research vessel the Calyoso.