1902 - 1920: A Class
These were designed for coastal defence work and had a limited range. They became known in Naval Circles as 'Fisher's Toys' - a reference to Admiral Sir John Fisher who was a keen advocate of the submarine as a weapon of war.
Even before trials, it was apparent that the Holland boats would have limited speed and endurance on the surface and, as a result - which highlighted the changing attitude within the Admiralty - a larger submarine was ordered with the hope of overcoming these problems.
This, the submarine A1, although based on the Holland Class was of all British design (Capt Bacon, Inspecting Captain of Submarines, and Vickers, Sons and Maxim). She was 40 feet longer than the Holland's, and, at 207 tons, of about two-thirds more displacement. Power was also increased.
Laid down in 1902, she was the first of a class of thirteen - all completed at barrow between 1903 and 1905, except for A13 which was an experimental craft, fitted with diesel engines instead of petrol engines, which was completed in 1908.
The hoped for improvements in surface performance were achieved as the class developed and further changes in power were made, but in underwater performance there was little gained over the Holland Class
During the building of A1, it was decided that greater torpedo capability was required and from A2 onwards two bow tubes were fitted, side-by-side. So many modifications were made to the various boats during the building programme, that the A Class could be considered as four classes: A1; A2 to A4; A5 to A12 and A13, the diesel version. But the A Class still had limitations in speed and endurance, accommodation was cramped and they were not good sea boats.
Once more, in an attempt to improve on these shortcomings, a larger vessel was designed some 40 feet longer than A1, 10 inches more in beam, and 100 tons more displacement. This was the start of the B Class.
The First Diesel
What appears to have escaped the eyes of researchers so far is that the first diesel-engined submarine in the Royal Navy was HMS A13 Launched at Barrow in 1905. The boat was fitted with what is described now as "a heavy oil engine." It was in fact a diesel engine designed and built by Vickers.
Ruston-Hornsby - then Hornsby, had designed an oil engine but it was rejected on account of being "too heavy." The Vickers design was used instead. Yet diesel propulsion was not generally used until the advent of the D Class boats.