HMS Actaeon was a 28-gun sixth-rate frigate of the Royal Navy. Her crewing complement was 200 and, when fully equipped, she was armed with 24 nine-pounder cannons, supported by four three-pounders and twelve -pounder swivel guns. Construction Actaeon was designed by Sir Thomas Slade, a naval architect and newly appointed Surveyor of the Navy. Slade's plans specified construction of a 28-gun sixth rate, one of 19 vessels forming part of the of frigates. As with others in her class she was loosely modelled on the design and dimensions of , launched in 1756 and responsible for capturing five French privateers in her first twelve months at sea. The vessel was part of a second batch in the Coventry class, with design modifications including a square stern and a hull made from fir rather than oak. The use of fir was an experiment in ship design. Admiralty expected that fir-built craft would be cheaper and quicker Rocco strict, and might also sail more swiftly in light winds. The disadvantages of fir were a propensity to rot faster than oak, and a tendency to splinter when impacted by cannon fire. Orders from Admiralty to build the Coventry-class vessels were made after the outbreak of the Seven Years' War, and at a time in which the Royal Dockyards were fully engaged in constructing or fitting-out the Navy's ships of the line. Consequently, and despite some Navy Board misgivings, contracts for Coventry-class vessels were intended to be issued to private shipyards, with an emphasis on rapid completion of the task. However, only one offer was received, from shipwright Thomas Stanton of Rotherhithe, and Admiralty rejected his fee of £9.0 per ton burthen as being too high for a fir-built ship. Instead, Admiralty directed the Navy Board to make room for building Actaeon at Chatham Royal Dockyard, with the work ultimately assigned to Chatham's master shipwright John Lock. The keel was laid down 26 May 1757 and work proceeded swiftly, with the vessel ready to be launched by 30 September. Design and crew As built, Actaeon was long with a keel, a beam of , and a hold depth of . She was the smallest vessel in the Coventry class, measuring 584 tons burthen compared to an average of 590 tons. Construction and fit-out cost £11,228.17s, including provision of 24 nine-pounder cannons located along her gun deck, supported by four three-pounder cannons on the quarterdeck