She served mostly uneventfully at Macao and Manila; in the latter location the ship's captain was discovered by the Spanish to be using his barge to smuggle dollars.

In December 1815 the ship was deemed to be in such bad condition with rot that she was sent home, described by William Henry Dillon, captain of an accompanying vessel, as "in a very crazy state".

This new theatre of operations, with the Napoleonic Wars ongoing, was expected to put a strain on the existing fleet of Royal Navy frigates, and so more were needed to be built.

Designed by the Surveyor of the Navy, Sir William Rule, the Scamander class was one of those put into construction to fill this need.

[2] Using pine for construction meant that the usually long period of time between keel laying and launching could be dramatically decreased to as little as three months.

[11] By July the frigate was serving at Macao, from where she transported the East India Company employee Thomas Pattle to Manila so that he could recover from dropsy.

[16] While sailing off Luzon on 13 November Alpheus encountered the 38-gun frigate HMS Horatio, whose crew was beset with sickness.

Langford decided to refit the ship and then return to England, as the war establishment in the East Indies was coming to an end.

She then spent some time at Mauritius weathering storms off the coast of Africa, as her rotten timbers would have made sailing through them very dangerous.

[24] While doing so she encountered Horatio on 20 August, whose commander Captain William Henry Dillon described Alpheus as "in a very crazy state" despite the refit.

Alpheus's hull was in a bad state, and while making the journey Langford kept the ship at a slow pace to avoid damaging it further, as a result of which Horatio sailed on alone on 27 August.

[6][8] Amongst the cargo brought from the East Indies by the ship was part of a Persepolis relief, wall stones from Babylon, a portrait of Arthur Wellesley, 1st Duke of Wellington, an Arabian horse, and a tortoise.