Hi Martin. They are the bowsing-in lines for the Marine Evacuation Systems. These two ships have six MES each and are the first ferries to have no lifeboats, depending entirely on MES. All the P&O ferries use Marin Ark MES, the diagram shows a typical one of a slightly earlier design. The DFDS ferries use a different type manufactured by Viking.
The photo of the Spirit of France shows two of her MES. The MES stations are behind the blue doors. These open and a carriage moves out and deploys the chutes and liferafts. The liferafts inflate on hitting the water and are held against the ships side by the bowsing-in lines. The photo shows one of her fast rescue boats being recovered after going out for a jolly. These are used to shepherd the liferafts, and to whiz out for a man overboard, etc.
