HMS F1 was the lead boat of the F Class of coastal patrol submarines and was the only one of the class built at Chatham.


The F Class were a new design of submarine hull which featured a double hull (where the ballast tanks are contained in the gap between an inner pressure hull and an outer hull) rather than the saddle tanks used on previous designs. This, in theory, made for a more streamlined hull and is used today on many modern submarines. The downside was that double-hulled submarines are more complex and more expensive to build. The design of the F Class was based on that of the experimental V class, but featured a number of small improvements including a stern torpedo tube.


Line drawing of an F Class boat





The F class were not considered a success and of the ten boats ordered, only three were completed.


HMS F1 was laid down on No 7 slip on 1st December 1913 and was launched into the Medway by Mrs Gallagher on 31st March 1915. After fitting out she commissioned at Chatham on 14th August. After her sea trials, she was fitted with larger hydroplanes and substantial guards for them.


On completion, HMS F1 was 151 feet long and 16 feet, one and a quarter inches wide at the beam. She displaced 353 tons surfaced and 525 tons dived. Armed with 3 18" torpedo tubes, two in the bow and one in the stern, she carried a 2pdr (40mm) deck gun and required a crew of 19 men.


In common with her two F class sister-boats, HMS F1 didn't see any action during the First World War, although she conducted war patrols in the North Sea based out of Harwich and Great Yarmouth and in the English Channel based out of Dover between commissioning and 1918. In 1918, she was transferred to Portsmouth and assigned to a training role and continued in that when she and her sisters were moved to Campbelltown.


HMS F3 at sea. F1 would have been identical.





After the war, the Royal Navy had no use for them and HMS F1 was decommissioned in 1919 and was broken up in Portsmouth in 1920, despite being only 5 years old.