The War Illustrated, Volume 4, No. 75, Page 134, February 7, 1941.

During the struggle for air supremacy over our shores a vast number of German aircraft have been shot down into the sea or have been so seriously damaged has been forced to alight in the ocean. Many German airmen have been rescued by British sailors, but to afford succour to those who descend unseen, the Germans have established floating refuges moored off the coastline of Holland, Belgium, and France. These refuges, in appearance rather like conning-tower of a submarine, contain everything likely to be needed by a marooned airman. A gangway from the water to the deck gives access to the refuge, which is equipped with sleeping bunks, medical stores, food and emergency equipment, including a flagstaff for hoisting distress signals. These floating sick bays are painted bright yellow to increase their visibility.