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.   OPERATION P.A.3  Line defined 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.  HM Ships Seagull and SHARPSHOOTER Wind NNE, 2-3, weather overcast with snow showers.  Remarks The 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.  On 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.  When 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 10½ fathoms. (b) The remainder of the mines swept up were at a depth below the surface of more than 10½ fathoms but less than 15 fathoms.  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.