An endeavour has been made to give in this book a reasonable detailed record of the development in design and equipment of HM Submarines from the Holland Class laid down in 1901 to the Porpoise Class the design of which started in 1930.
The contents have been developed from notes taken personally from official records and drawings between the years 1928-39. During this period I was involved with submarine refits at HM Dockyard Devonport, in the Submarine Design Section at the Admiralty London, on the staff of Rear-Admiral (Submarines) at Blockhouse and as Principal Ship Overseer of submarines building at Vickers-Armstrong Ltd at Barrow-in-Furness.
I found, not unexpectedly, that the details given for a submarine or class of submarines often varied considerably. This depended on the source of the information, the practice adopted by the reporting authority and primarily on whether the details referred to the vessel as designed or as first built or after some years in service. To obtain as true a comparison between types as possible an attempt has been made to standardise the figures quoted in this book as explained in Chapter 2.
The book is really in two parts. Chapters 1-17 deal with individual classes whilst Chapters 18-32 deal with the progressive development of individual items of design or equipment throughout the classes.
For easy reference the particulars given in detail in the various chapters have been summarised in the Appendices. It is stressed that the details given refer to the vessel as designed or as on completion of building when changes were made from the design during building. They apply therefore to the first boat of the class as first completed. The plates showing General Arrangements of submarines are in general as fitted arrangements but not necessarily as first fitted.