Here is a suggestion for a bomb ketch that could eventually be added to replace the mortar brig, or simply serve as another mortar vessel: HMS Granado
Length: 64 ft 5 in (19.6 m) (gundeck) 50 ft 6 in (15.4 m) (keel) Beam: 23 ft 5 in (7.1 m) Depth of hold: 10 ft 0 in (3.0 m)