1928, the Director of Tactical Division (DTD) stated that: 'The ability to dive to 500 feet was introduced principally in order that pressure hulls of these submarines should be more capable of withstanding the effect of the explosion of a depth charge. Submarine officers do not visualize any intentional diving to such depths as 500 feet though the ability to do so is an asset in the event of an involuntary deep dive which might cause the submarine to go much deeper than was intended'.
When on patrol, the daily fuel consumption for all classes, allowing 12 hours diving, 12 hours steaming at slow speed and eight hours charging, was given as 2.1 tons per day, except in Orpheus (the only vessel of the Odin Class to be fitted with a Vulcan clutch) where the consumption was 2.6 tons per day.
