Thermal conditions in warships refitting at H.M. Naval Base, Singapore.

Numerous investigations have been carried out in recent years to determine the thermal environment in warships at sea in the tropics. As far as is known there has been no previous study of the thermal environment in which men work when a ship is refitting in a dockyard in the tropics. The aim of this investigation was to assess these conditions by measuring air temperatures in a wide variety of compartments in different classes of ships during a refit, and to relate the findings to the levels of warmth above which it is known that increasing numbers of men are likely to collapse or become inefficient. Temperature recordings were made during July, August, and September, 1951, in an aircraft carrier repair ship, two cruisers, a frigate, and a submarine. They were in dry dock, except on one occasion when the ship was alongside. Thirty-five compartments in all were investigated. An important part of the work was to estimate the effect on the thermal environment of artificial ventilation or recirculation of air. For the larger ships a refit usually lasts about eight to 10 weeks, of which five to seven weeks are spent in dry dock; for submarines a refit takes much longer. The conditions in a ship during a refit are abnormal, but vary slightly from ship to ship. While in dry dock, boilers are shut down and machinery is not running. As a result there is much less " wild heat" circulating within the ship than under normal conditions, but as power is not available there is usually no forced ventilation supply or exhaust. Dockside power is used for lighting and the recirculation of air between decks. On occasions a forced fresh air supply can be delivered through the punka louvre system to certain parts of the ship, but in many compartments the only method of circulating the air is by means of " doublebottom" fans, i.e., fans with hose extensions normally used to ventilate the space between the outer and inner plates below the water line (Fig. 1). As it is frequently not possible to arrange the intake from the outside air, the main effect is to increase