Source: ADM 199/184 HMS Seagull
Minesweeping Operation PA3
From: The Commanding Officer, HMS SEAGULL
Date: 15th March 1940
To: Flag Officer in Charge, Invergordon.
defined by four danbuoys laid by HMS ‘ Teviot ????’ in the vicinity
of position 58 degrees 25 minutes North, 1 degree 14 minutes West.
mines cut - N2 Mark 8 Star British moored mines, destroyed by rifle
Ships Seagull and SHARPSHOOTER
NNE, 2-3, weather overcast with snow showers.
formation 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.
entering 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.
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
The original mine or group of mines swept up were definitely at an
incorrect depth of about 10˝ fathoms.
The remainder of the mines swept up were at a depth below the
surface of more than 10˝ fathoms but less than 15 fathoms.
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.