Great submarine activity occurred at this time in the vicinity of the Orkneys and Shetlands. The _Dryad_ sighted a submarine on the 24th in Lat. 58.35 N., Long. 1.45 W.; a second was sighted by an armed trawler off Copinsay on the same day; and a third was sighted from the shore, proceeding to the eastward through the Pentland Firth. On the 25th U 16 was sighted by a collier and trawler in Lat. 58.46 N., Long. 2.15 W., and later by the mine-sweeping gunboat _Skipjack_ not far from this position. On the return of the Fleet arrangements were made for constructing, with Fleet resources, net obstructions across the Hoy entrance to Scapa Flow, and, in view of the attempt of U 18, all patrols were stiffened to the utmost extent possible. During November 27th and 28th the strong gale continued, interfering considerably with the work on the submarine obstructions. Several reports of the sighting of submarines in harbours in the north of Scotland, the Orkneys and Shetlands were received during the last days of November, and destroyers and patrol craft were kept very busy in searching the various bays and harbours. In many cases charges were exploded on the bottom in bays in which it was considered that a submarine might be lying, in the hope of forcing her to the surface. No known result, however, was obtained. The Fleet remained in the various bases until the end of the month, the ships in Scapa Flow carrying out gunnery and torpedo practices and working at the obstructions. The _King George V._, which had just returned from refit at a dockyard, developed condenser defects necessitating partial retubing; she was the fourth battleship in which this defect had occurred since the War started, a period of only four months, and it will be realised that such wholesale breakdowns caused me uneasiness. During November the work of sinking block-ships in all the entrance channels to Scapa Flow, except the Hoxa and Hoy entrances, was carried out. Unfortunately the block-ships had been sent up in a light condition without cement ballast which, I was informed, could not be supplied, and they began in many cases to break up or to shift their position during the winter gales. This fact, combined with the great difficulty experienced in sinking them in the exact positions required owing to the strong tides prevailing (up to at least eight knots in strength), and the very short periods of slack water, rendered the work of blocking only partially effective. At the end of November the effective state of the Grand Fleet was as follows: Fleet-Flagship: the _Iron Duke_. _1st Battle Squadron_: 7 ships, the _Neptune_ being away refitting. _2nd Battle Squadron_: 7 ships, of which one, the _King George V._, was disabled, retubing condensers. _3rd Battle Squadron_ (Pre-Dreadnoughts): 7 ships, one ship refitting at twelve hours’ notice for steam, and the 8th ship returning from a dockyard refit.