A danlayer was a type of vessel assigned to minesweeping flotillas during and immediately after World War II. They were usually small trawlers, fitted for the purpose of laying dans. A dan is a marker buoy which consists of a long pole moored to the seabed and fitted to float vertically, usually with a coded flag at the top.

Dan laying was an important part of minesweeping, and boats were fitted specifically for this purpose. The task of a danlayer was to follow the minesweepers as they worked an area, and lay the dans which defined the area swept and made it obvious where the clear channels were. This would also help the minesweepers cover areas accurately without gaps and unnecessary overlaps.[1] A danlayer worked with a minesweeper flotilla when large areas of sea were to be clear-swept.

HMS Sir Galahad
HMS Sir Galahad, a Round Table-class trawler displacing 440 long tons, was converted to a danlayer in 1944 and used to support the Normandy landings

List of danlayers


Since Germany had been an exponent of mine warfare since the 1920s, it was natural that the Kriegsmarine used a number of danlayers during World War II. Danlayers of the Kriegsmarine included the following vessels:

  • The 800-ton, 176-foot B 206 - This vessel was ceded to France in 1946 and outfitted as the surveying vessel Ingenieur-Hydrographe Nicolas
  • The 120-ton, 82-foot B 253, B 254, B 261, B 262, B 264, B 273 and B 275 - These were ceded to France in 1946 and renamed Rachgoun, Treberon, Tourteau, Cassidaign, Les Madeleines, Habibas and Crabe, respectively. Tourteau and Crabe became surveying tenders, while the others were employed as small harbor transports for naval personnel.
  • The 600-ton, 180-foot B 281 (formerly the patrol trawler V 204, originally named Zieten) - This vessel was ceded to France in 1946 and renamed Astrolabe as a surveying tender.
  • The 500-ton, 137-foot B 282 and B 284 (formerly the whalers Treff. 6 and Traff. 2), respectively) - Both were ceded to France in 1946 and renamed Estafette and Sentinelle as surveying tenders.


Danlayers employed by the Royal Navy during the extensive mine clearance operations following World War II included the following Isles-class trawlers.

  • Hellisay (T391)
  • Hermetray (T392)
  • Imersay (J422)
  • Orsay (J450)
  • Ronay (J429)
  • Sandray (J424)
  • Scaravay (J425)
  • Sheppey (T292)
  • Shillay (J426)
  • Sursay (J427)
  • Tahay (J452)
  • Tocogay (J451)
  • Trodday (J431)
  • Vaceasay (J432)
  • Vallay (J434)
  • Wiay (J441)

Two Round Table-class trawlers, Sir Lanceleot (T228) and Sir Galahad (T226) were converted from minesweepers to danlayers prior to the Normandy landings.

In 1944, prior to the Allied invasion of Normandy, the Admiralty-type Motor Mine Sweepers Nos. 141, 142, 238, 239, 240, and 214 were converted to danlayers and redesignated as follows: HMS Burfin, HMS Cottel, HMS Fichot, HMS Jude, HMS Quirpon, HMS St. Barbe, respectively. All were twin-screw, wooden, 105-foot, coastal-minesweeping sloops built by Steers Ltd. at Saint John, New Brunswick, Canada between 1941 and 1943.

New Zealand

Danlayers employed by the Royal New Zealand Navy during World War II

  • HMNZS Coastguard (T12)
  • HMNZS Kaiwaka (T14)
  • HMNZS Nora Niven (T23)
  • HMNZS Phyllis T22


  1. ^ McDougall RJ, New Zealand Naval Vessels, p. 55. Wellington, NZ: Government Printing Office, 1989. ISBN 978-0-477-01399-4


  • Francis E. McMurtrie and Raymond V.B. Blackman (eds.), Jane's Fighting Ships 1949-50, pp. 63, 193, 194. New York: The McGraw-Hill Book Company, Inc., 1949.
  • H.T. Lenton and J.J. Colledge, Warships of World War II, pp. 534 & 538, London, UK: Ian Allan Ltd., 1964.
Amenities ship

An amenities ship is a ship outfitted with recreational facilities as part of a mobile naval base. Amenities ships included movie theaters and canteens staffed by mercantile crews of the Royal Fleet Auxiliary service. These ships were intended to provide a place where British Pacific Fleet personnel could relax between operations.

Ammunition ship

An ammunition ship is an auxiliary ship specially configured to carry ammunition, usually for naval ships and aircraft. An ammunition ship′s cargo handling systems, designed with extreme safety in mind, include ammunition hoists with airlocks between decks, and mechanisms for flooding entire compartments with sea water in case of emergencies. Ammunition ships most often deliver their cargo to other ships using underway replenishment, using both connected replenishment and vertical replenishment. To a lesser extent, they transport ammunition from one shore-based weapons station to another.

Coastal minesweeper

Coastal minesweeper is a term used by the United States Navy to indicate a minesweeper intended for coastal use as opposed to participating in fleet operations at sea.

Because of its small size—usually less than 100 feet in length—and construction—wood as opposed to steel—and slow speed—usually about 9 or 10 knots—the coastal minesweeper was considered too fragile and slow to operate on the high seas with the fleet.

Minesweeping, in conjunction with fleet activities, was usually relegated to the diesel-driven steel-hulled AM-type minesweepers, later to be replaced by the wood-hulled MSO-type minesweeper with aluminum engines.

Coastal submarine

A coastal submarine or littoral submarine is a small, maneuverable submarine with shallow draft well suited to navigation of coastal channels and harbors. Although size is not precisely defined, coastal submarines are larger than midget submarines, but smaller than sea-going submarines designed for longer patrols on the open ocean. Space limitations aboard coastal submarines restrict fuel availability for distant travel, food availability for extended patrol duration, and number of weapons carried. Within those limitations, however, coastal submarines may be able to reach areas inaccessible to larger submarines, and be more difficult to detect.

Destroyer tender

A destroyer tender, or destroyer depot ship in British English, is an auxiliary ship designed to provide maintenance support to a flotilla of destroyers or other small warships. The use of this class has faded from its peak in the first half of the 20th century as the roles of small combatants have evolved (in conjunction with technological advances in propulsion reliability and efficiency).

Fighter catapult ship

Fighter catapult ships also known as Catapult Armed Ships were an attempt by the Royal Navy to provide air cover at sea. Five ships were acquired and commissioned as Naval vessels early in the Second World War and these were used to accompany convoys.

The concept was extended to merchant ships which were also equipped with rocket assisted launch systems and known as Catapult Aircraft Merchantmen (CAM ships).

General stores issue ship

General stores issue ship is a type of ship used by the United States Navy during World War II and for some time afterwards.

The task of the general stores issue ship was to sail into non-combat, or rear, areas and disburse general stores, such as canned goods, toilet paper, office supplies, etc., to ships and stations.

Guard ship

A guard ship is a warship assigned as a stationary guard in a port or harbour, as opposed to a coastal patrol boat which serves its protective role at sea.

Isles-class trawler

The Isles-class trawlers were a class of naval trawler used by the Royal Navy, Royal Canadian Navy and Royal New Zealand Navy during World War II.

The type comprised 197 vessels built between 1939 and 1945 in the nearly identical Isles, Dance, Tree and Shakespearian classes. Generally similar to the Castle class naval trawlers of 1916-18, though somewhat larger, they were mainly used on minesweeping and harbour defence duties. Most were armed with one 12-pounder gun (76mm) and three or four 20 mm Oerlikon AA guns with 30 depth charges. In the Dance class a 4-inch AA gun (102 mm) was fitted in place of the 12-pdr, and there were six 20 mm Oerlikons in Annet, Bressay, Damsay, Fiaray, Foulness and Lindisfarne. Four of the trawlers were given 'Bird' names when converted to controlled minelayers in 1943-44: Blackbird (M15), Dabchick (M22), Stonechat (M25) and Whitethroat (M03). A total of 23 of these trawlers were lost during the war. Six trawlers were loaned to Canada in 1942-45 and five to Norway in 1943-45.

Postwar, 17 of the trawlers were disarmed as wreck disposal vessels: Bardsey (DV13), Bern (DV4), Caldy (DV5) Coll (DV6), Earraid (DV7), Fetlar (DV8), Flatholm (DV9), Graemsay (DV10), Lindisfarne (DV11), Lundy (DV12), Neave (DV14), Scalpay (DV15), Skomer (DV16), Steepholm (DV17), Switha (DV18), Tiree (DV19), and Trondra (DV20). At least five were employed as danlayers (laying and retrieving dan buoys during minesweeping operations): Imersay (J422), Sandray (J424), Shillay (J426), Sursay (J427) and Tocogay (J451). After decommissioning, Switha and Coll were converted to oil tank cleaning vessels for dockyard service in 1949-50.

By 1949 there remained in service of this type 31 trawlers and four controlled minelayers in the Royal Navy, one controlled minelayer in the Royal Canadian Navy, and four trawlers in the Royal New Zealand Navy. An additional 16 were in service in the Italian Navy and six in the Portuguese Navy. Most of the surviving Royal Navy examples were discarded in the 1950s, but a few remained until the 1960s. Two acquired postwar by the Federal German Navy remained in service as training vessels well into the 1970s, with one, Trave (ex-Dochet), resold to Turkey for further service in 1977.

Light aircraft carrier

A light aircraft carrier, or light fleet carrier, is an aircraft carrier that is smaller than the standard carriers of a navy. The precise definition of the type varies by country; light carriers typically have a complement of aircraft only one-half to two-thirds the size of a full-sized fleet carrier. A light carrier was similar in concept to an escort carrier in most respects, however light carriers were intended for higher speeds to be deployed alongside fleet carriers, while escort carriers usually defended convoys and provided air support during amphibious operations.

List of ships of the Royal New Zealand Navy

Sortable list of commissioned vessels of the Royal New Zealand Navy from its formation on 1 October 1941 to the present. It does not include vessels of the New Zealand Division (1921–1941) or New Zealand Naval Forces (1913–21) or earlier vessels up to 1913.

Merchant raider

Merchant raiders are armed commerce raiding ships that disguise themselves as non-combatant merchant vessels.

Mine countermeasures vessel

A mine countermeasures vessel or MCMV is a type of naval ship designed for the location of and destruction of naval mines which combines the role of a minesweeper and minehunter in one hull. The term MCMV is also applied collectively to minehunters and minesweepers.


A minehunter is a naval vessel that seeks, detects, and destroys individual naval mines. Minesweepers, on the other hand, clear mined areas as a whole, without prior detection of mines. A vessel that combines both of these roles is known as a mine countermeasures vessel (MCMV).

Net laying ship

A net laying ship, also known as a net layer, net tender, gate ship or boom defence vessel was a type of small auxiliary ship.

A net layer's primary function was to lay and maintain steel anti-torpedo or anti-submarine nets. Nets could be laid around an individual ship at anchor, or around harbors or other anchorages. Net laying was potentially dangerous work, and net laying seamen were experts at dealing with blocks, tackles, knots and splicing. As World War II progressed, net layers were pressed into a variety of additional roles including salvage, troop and cargo transport, buoy maintenance, and service as tugboats.

Ocean boarding vessel

Ocean boarding vessels (OBVs) were merchant ships taken over by the Royal Navy for the purpose of enforcing wartime blockades by intercepting and boarding foreign vessels.

Repair ship

A repair ship is a naval auxiliary ship designed to provide maintenance support to warships. Repair ships provide similar services to destroyer, submarine and seaplane tenders or depot ships, but may offer a broader range of repair capability including equipment and personnel for repair of more significant machinery failures or battle damage.

Shin'yō-class suicide motorboat

The Shinyo (震洋, Shin'yō, "Sea Quake") were Japanese suicide motorboats developed during World War II. They were part of the wider Japanese Special Attack Units program.

Submarine tender

A submarine tender is a type of depot ship that supplies and supports submarines.

Aircraft carriers
Patrol craft
Fast attack craft
Mine warfare
Command and support


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