A danlayer was a type of vessel assigned to minesweeping

Minesweeper (ship)

A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...

 flotillas during and immediately after World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. They were usually small trawlers

Naval trawler

A naval trawler is a vessel built along the lines of a fishing trawler but fitted out for naval purposes. Naval trawlers were widely used during the First and Second world wars. Fishing trawlers were particularly suited for many naval requirements because they were robust boats designed to work...

, fitted for the purpose of laying dans. A dan is a marker buoy

Buoy

A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...

 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. A danlayer worked with a minesweeper flotilla when large areas of sea were to be clear-swept.

Germany

Since Germany had been an exponent of mine warfare since the 1880s, it was natural that the Kriegsmarine

Kriegsmarine

The Kriegsmarine was the name of the German Navy during the Nazi regime . It superseded the Kaiserliche Marine of World War I and the post-war Reichsmarine. The Kriegsmarine was one of three official branches of the Wehrmacht, the unified armed forces of Nazi Germany.The Kriegsmarine grew rapidly...

 used a number of danlayers during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. 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.

Britain

Danlayers employed by the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 during the extensive mine clearance operations following World War II included the following Isles-class trawler

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....

s.

• 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 trawler

Round Table class trawler

The Round Table class was a small class of trawlers built for the British Royal Navy in 1941/2. The class were built by two Aberdeen shipbuilding firms Hall, Russell & Company and J. Lewis & Sons Ltd....

s, Sir Lanceleot (T228) and Sir Galahad

HMS Sir Galahad (T226)

HMS Sir Galahad was a trawler built for the British Royal Navy in 1941. Post war it was sold into civilian service and was wrecked in 1957 after running aground off the Isle of Mull.-Construction and war service:...

 (T226) were converted from minesweeper

Minesweeper (ship)

A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...

s 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

Royal New Zealand Navy

The Royal New Zealand Navy is the maritime arm of the New Zealand Defence Force...

during World War II

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