Sir John Henslow designed the class on the model of flat-bottomed Thames barges.

[1] Commander Horace Pine recommissioned her in September and she was stationed at Chatham to protect the River Medway.

The ringleader of the mutiny, Richard Parker, put a man, Thomas Appleyard, aboard her to take command of her.

Appleyard later received a court martial and was hanged aboard Firm,[2] then at Gillingham Reach.

[b] On 21 August 1799 Bulkeley Mackworth Praed, newly released from enemy custody, was promoted to Commander on Firm,[4] which served in the Channel.