Source: ADM 199/184 LL sweep in Fleet Minesweepers

From: DTM Admiralty
Date: 12^th July 1940
To: DEE

The subjoined extracts from a report on recent sweeping operations carried out by HM Ships HMS BRAMBLE and Speedy are referred for information and comment. 

It is of interest to note that this is the first clearance operation by the LL sweep of a defined area known to contain magnetic mines. The sweep was for RED mines only and three were exploded. 

It is considered that the gear was subjected to a fair test since out of a total of 77 ¼ hours under way, 54 ¼ were spent actually sweeping. 

Ships were stationed 220 yards apart in under 10 fathoms and 250 yards apart in 10 fathoms and over. The average speed of sweeping over the ground was 6 ¾ knots. 

1^st mine exploded almost underneath starboard sweep 70 yards astern of short tail.

2^nd mine midway between sweeps, 70 yards astern of short tail.

3^rd mine nearer port sweep 30 yards astern of short tail.  

No damage was done to the Callender Cable in either ship by the 3 detonations, even though one mine detonated almost directly beneath BRAMBLE’s tail.

 

From:          The Senior Officer, 1^st Minesweeping Flotilla, HMS BRAMBLE
Date:                17^th June 1940
To:                   The Commander in Chief, Home Fleet.

Sweepers:         BRAMBLE, Speedy
Danlayers:       Yacht Seaflower, Drifters Guiding Light and Olive Tree. 

Wind:               Light, variable, usually freshening force 2 from the ENE in the evenings.
Visibility:          Considerable fog which stopped sweeping whenever visibility dropped below one mile. 

Mines:              All ground magnetic.

1^st Mine:           129° Tarbat Ness Lt House 4.45 miles, almost underneath starboard sweep, 70 yards astern of short tail.

2^nd Mine:          136½° Tarbat Ness Lt House 3.45 miles midway between sweeps, 70 yards astern of short tail.

3^rd Mine:           141½° Tarbat ness Lt House 3.5 miles nearer port sweep, 30 yards astern of short tail. 

No damage was done to the Callender Cable in either ship by the 3 detonations, even though one mine detonated almost directly beneath BRAMBLE’s tail.

Although the two drifters acting as danlayers had never before carried out this duty, they worked extremely well and efficiently. They had only two cork dan buoys when they arrived, but six complete dans were lent from the sweepers. It is urgently requested that these two drifters may be allocated to the 1^st MSF for danlaying duties. They are eminently more suitable than the yachts Hinba and Bunting who have recently been taken away for there duties. If danlayers are not provided permanently and thus gain experience, it cannot be expected that clearances can be accurate under conditions when navigational fixes are not continuously available. The yacht Seaflower proved herself a most efficient and suitable danlayer.  

Diary of Events during Magnetic Clearance of QZX44 

Total hours sweepers under way          77 ¼

Total hours sweepers sweeping            54 ¼

Total hours danlayers under way           90 ¼

Average speed of sweeping                    6 ¾ knots

Source: ADM 199/184 Clearance of QZX 44 BRAMBLE

From: Senior Officer, 1^st Minesweeping Flotilla, HMS BRAMBLE

Date:  24^th July 1940

To:     Commander in Chief Home Fleet

The water immediately to the NE of the limit of the clearance as shown in the tracing had been thoroughly searched for a further three cables when leaving the area at the end of each lap, and approaching it for the next. This was not included in the tracing of water cleared because overlaps were not guaranteed.

Six mines had been accounted for, viz:

          3 by 1^st Minesweeping Flotilla

          1 which caused area to be declared

          1 which sank the Durham Castle

          1 detonated by magnetic sweep further south

These were thought to constitute the complete lay of a small U-boat.

M H Evelegh

Captain