HMS Acorn explained

Six ships of the Royal Navy have borne the name HMS Acorn. A seventh was planned but never completed:

• was a 22-gun ship hired between 1649 and 1654.
• was an 18-gun Cormorant-class ship-sloop launched in 1807 and broken up in 1819.
• was an 18-gun sloop launched in 1826 and wrecked in 1828.
• HMS Acorn was to have been an 18-gun sloop, but the order was cancelled in 1831.
• was a 12-gun brig launched in 1838. She was used as a coal hulk from 1861 and was sold in 1869.
• was a composite screw sloop launched in 1884 and sold in 1899.
• was an launched on 1 July 1910 and sold in 1921.