1903 - 1906: C Class
38 C Class were built between 1905 and 1910 - all but six being built at Barrow. The other six were built at Chatham - (First instance of Lead Yard?).
The B Class and C Class were almost identical, being larger versions of the A Class, with petrol engines for surface propulsion and batteries for propulsion when submerged.
Unluckiest vessel of the era was surely the submarine A1. Some of the things that happened in her have served as a warning to all submariners from that day to this. Before delivery, A1 suffered the first explosion in a submarine - this was due to a pocket of hydrogen gas.
When on passage off Land's End the crew had to abandon ship when seawater entered the batteries, filling the submarine with choking chlorine gas. When she was eventually delivered to Portsmouth, A1 was berthed in a remote part of the harbour, so that this 'dangerous craft' could do as little damage as possible if she blew up.
In the summer of 1904, during manoeuvres against the Fleet, A1 was dispatched to attack a battleship. When she neared Spithead, the ocean liner SS Berwick Castle made an approach. No one on watch noticed the tiny periscope jutting from the waves, nor did any of her crew feel anything more than a slight tremble as the massive ship ran over a small unknown object. When A1 failed to report that night, it was realised that a disaster had occurred. Eleven men lost their lives in this tragedy, which caused great concern throughout the country.
The early years of submarine building were a time of innovation:
In 1908, approval was given to fit C12 to C16 with 'airlocks' or 'air-traps' as they were sometimes known. Divided into three airlocks, with a fourth fitted on the starboard side, the enclosed spaces had stowed in them sixteen diving helmets - one for each member of the crew. The escape route was through the torpedo hatch. These airlocks were subsequently fitted to all Band C Class submarines.
The first submarine to carry a boat appears to have been C1, which had a 10t berthon boat - a practice that was adopted for the remainder of the class. In 1905, the hitherto unknown dangers of petrol vapour caused an explosion in A5, which killed her commander and several others, and led to the move to adopt diesel engines, which used heavy oil with a higher flash point, and A13 was fitted with an experimental diesel engine for trials at sea.
During these trials, the C Class vessels continued to be fitted with the same sixteen cylinder Wolseley petrol engine as in A5 to A12, but now made by Vickers and called the Vickers engine. In C19 to C38 the number of cylinders was reduced to twelve. Following the trials in A13, diesels were adopted for the D Class, and the use of petrol engines in new designs came to an end.