Designed by Nathaniel Barnaby,[2] the Royal Navy Director of Naval Construction, the hull was of composite construction; that is, iron keel, frames, stem and stern posts with wooden planking.

Propulsion was provided by a 2-cylinder horizontal compound-expansion steam engine of 850 indicated horsepower (634 kW) driving a single screw.

[2] All the ships of the class were built as barque-rigged vessels, except Icarus, which had no main yards provided, making her a barquentine.

The experiment cost £10,000 more than the British-built versions, and incurred substantial delay; it was not repeated, and Melita remained the only warship of any significant size ever built in Malta for the Royal Navy.

[3] Media related to Mariner class gunvessel at Wikimedia Commons