In the original operational DEADLIGHT orders distances between the laying up ports and the disposal point were stated as being 130 miles from Moville (Lough Foyle) and 180 miles from Loch Ryan. This is how Moville (the nearest point on land to the mouth of Lough Foyle) makes its appearance. U-boats under tow were assembled off Moville prior to the final voyage.

Lisahally was/is the port for Londonderry. Existing mooring facilities were estimated to be able to accommodate up to 70 U-boats alongside Lisahally jetty. IWM image A.29241 shows an excellent overhead shot of approximately 40 U-boats moored here awaiting the final decision as to their disposal.

Loch Ryan was estimated to be able to accommodate up to 100 U-boats, moored in groups of five, offshore. The military port of Cainryan was the shore base, but all references in the planning documents referred only to Loch Ryan.

So, it is just a matter of geographical convenience when referring to shore-based reference points in the conduct of the Deadlight operations.