The Merlin-class packet boat of 1838 was a Sir William Symonds (the Surveyor of the Navy) design that was approved on 2 April 1838.

[1] The vessels were to be built for steam mail packet service on the Liverpool to Dublin route.

The initial two ships (Merlin and Medusa) were ordered in autumn 1838 from Pembroke Dockyard.

Merlin served on the West Coast of Africa and was sold for commercial use in 1863.

They had a pair of vertical single expansion (VSE) steam engines, rated at 312 nominal horsepower, that drove their paddlewheels.