A plan was devised to station submarines offshore from British naval bases, and then stage some action that would draw out the British ships to the waiting submarines. The battlecruiser had been damaged in a previous engagement, but was due to be repaired by mid May, so an operation was scheduled for 17 May 1916. At the start of May, difficulties with condensers were discovered on ships of the third battleship squadron, so the operation was put back to 23 May. Ten submarines—, , , , , , , , , and —were given orders first to patrol in the central North Sea between 17 and 22 May, and then to take up waiting positions. "U-43" and "U-44" were stationed in the Pentland Firth, which the Grand Fleet was likely to cross leaving Scapa Flow, while the remainder proceeded to the Firth of Forth, awaiting battlecruisers departing Rosyth. Each boat had an allocated area, within which it could move around as necessary to avoid detection, but was instructed to keep within it. During the initial North Sea patrol the boats were instructed to sail only north–south so that any enemy who chanced to encounter one would believe it was departing or returning from operations on the west coast (which required them to pass around the north of Britain). Once at their final positions, the boats were under strict orders to avoid premature detection that might give away the operation. It was arranged that a coded signal would be transmitted to alert the submarines exactly when the operation commenced: "Take into account the enemy's forces may be putting to sea".