The ship was sold shortly thereafter, and was subsequently acquired by the Brazilian Navy and renamed Rio Branco, utilized as a hydrographic survey vessel.

The ship was powered by a steam triple expansion engine initially fuelled by coal driving two screws rated at 2,000 indicated horsepower (1,491 kW).

[4] CGS Margaret was constructed by Thornycroft's Woolston Works at their yard in Southampton, United Kingdom in 1914 and delivered to the Department of Customs at Halifax, Nova Scotia in April 1914.

On 15 July 1915, Margaret and Sinmac were the first two vessels to arrive at Sydney, Nova Scotia to begin patrolling the Gulf of St. Lawrence.

In October, Sinmac was replaced by Sable II and Margaret's captain, Commander Burrard Smith became the senior officer of the Gulf patrol.

Grilse was able to make Shelburne, Nova Scotia under her own power, but Margaret was tasked with towing the damaged vessel to Halifax for refit.

[11] Following the end of the war, HMCS Margaret was returned to the CPS in December 1918, and carried out her first patrols in the Gulf of St. Lawrence and on the East Coast of Canada in early 1919.

Based at Gaspé, the ship's patrol was later extended into the Northumberland Strait as alcohol smuggling increased during American Prohibition.