Source: ADM 199/184 HMS SEAGULL Minesweeping Operation
The Commanding Officer, HMS SEAGULL
Date: 15th March 1940
To: Flag Officer in Charge, Invergordon.
by four danbuoys laid by HMS ‘ Teviot ????’ in the vicinity of
position 58 degrees 25 minutes North, 1 degree 14 minutes West.
45 mines cut
- N2 Mark 8 Star British moored mines, destroyed by rifle fire.
SEAGULL and Sharpshooter
2-3, weather overcast with snow showers.
as shown on the sketch was used, with SEAGULL passing about 50 yards
or less to the leeward of the danbuoys and cutting them with her
starboard sweep. This formation and procedure, it is considered,
made it reasonably certain that the sweeps would pass over the line
of mines and give a 100% skim, and also that it provided for the
possibility of a sweep parting.
the area, Sharpshooter immediately cut a group of mines, and in so
doing caught a mine in her otter which caused the float to dip. As
this is a fairly common occurrence when sweeping a report was not
immediately made. When this fact was reported I decided to accept
the increased depth of Sharpshooter’s sweep for some minutes, as (a)
although it is impossible to know what the increased depth of the
sweep would be, experience in the flotilla has shown that it may
not amount to very much, (b) I did not wish to order Sharpshooter to
heave out of the formation and lessen the certainty of a 100% skim,
which I considered to b my object, especially as at least one mine
had been proved to be at a wrong depth, (c) it was probable that the
float would reappear at any time, which is usual in such cases.
Sharpshooter continued to cut mines with her port sweep and the
float did not reappear, I was preparing to reconsider my decision,
when she ceased to cut them. I then decided to carry on with the
skim as before. Forty four mines (as counted subsequently) were
swept up in about the southern mile and a half of the line, and from
then on only one more was cut at about three miles from the southern
end. Sharpshooter’s float then reappeared with a mine in the otter
at the end of the sweep.
As it is
reasonably our aim that the increased depth of Sharpshooter’s sweep,
whatever it was, remained constant, and assuming that the majority
of the mines found their correct depth, it would appear that:
(a) The original mine or group of mines swept up were
definitely at an incorrect depth of about 10˝ fathoms.
(b) The remainder of the mines swept up were at a
depth below the surface of more than 10˝ fathoms but less than 15
The float and
kite wire settings were carefully rechecked at the conclusion of the
sweep in each ship and as the tables used have stood the test of
time and experience, there is no reason to suppose that there was
any serious error in the depth of the sweeps, although some slight
difference must have existed to account for the original mine being
cut by Sharpshooter and not by SEAGULL.