HMS Forth Wikipedia
Several ships of the Royal Navy have borne the name HMS Forth, after the River Forth:HMS Forth was to have been a 36-gun fifth rate, but she was renamed HMS Tigris in 1812 before being launched in 1813.
HMS Forth was a 50-gun fourth rate launched in 1813 and broken up in 1819.
HMS Forth was a 44-gun fifth rate launched in 1833. She was converted to a screw frigate and undocked in 1856. She became a coal hulk in 1869 and was renamed HMS Jupiter, before being sold in 1883.
HMS Forth was a Mersey class cruiser launched in 1886. She was to have been renamed HMS Howard in 1920, but this did not happen and she was sold in 1921.
HMS Forth was a submarine depot ship launched in 1938. She was renamed HMS Defiance between 1972 and 1978 and was sold for scrapping in 1985.
HMS Forth is one of five new Batch 2 River-class patrol vessels under construction. She is due to be commissioned in 2017.