Fir was cheaper and more abundant than oak and permitted noticeably faster construction, but at a cost of a reduced lifespan; the fir-built Coventry-class vessels lasted an average of eight years, three times less than their oak-built equivalents.

The naming followed a trend initiated in 1748 by John Montagu, 4th Earl of Sandwich, in his capacity as First Lord of the Admiralty, of using figures from classical antiquity as descriptors for naval vessels.

[4][5][a] In sailing qualities Boreas was broadly comparable with French frigates of equivalent size, but with a shorter and sturdier hull and greater weight in her broadside guns.

She was also comparatively broad-beamed with ample space for provisions and the ship's mess, and incorporating a large magazine for powder and round shot.

[7][8] She was also built with broad and heavy masts, which balanced the weight of her hull, improved stability in rough weather and made her capable of carrying a greater quantity of sail.

The disadvantages of this comparatively heavy design were a decline in manoeuvrability and slower speed when sailing in light winds.

[10][c] Among these other ranks were four positions reserved for widow's men – fictitious crew members whose pay was intended to be reallocated to the families of sailors who died at sea.

Flaws in her design were apparent even at this early stage; in December 1757 Captain Boyle advised Admiralty that the fir planks adjacent to the hatchways were already badly worn, as were the strakes along the hull.

Further, the sides of the vessel above the level of the deck were too low, leaving the crew exposed to enemy fire should Boreas run alongside an opposing ship.

[11] She also shared in the proceeds of the taking of the Bienfaisant and Echo, and the proceeds from the burning, sinking, or destroying the French warships Prudent, Entreprennante, Celebre, Capricieux, Apollon, and Fidelie in the harbour of Louisbourg, as well as the sundry naval stores, the recapture of the snow Muscliff, the sloop Dolphin, and the prize sloop Sellerie.

Hampshire chased the merchant frigate Prince Edward on shore where her crew set fire to her, leading her to blow up.

[20] On 19 October, Hampshire, with Lively and Valeur, cornered the King's frigate Fleur de Lis in Freshwater Bay, a little to leeward of Port-de-Paix; her crew too set her on fire.

The merchant frigate Duc de Choiseul, of 32 guns and 180 men under the command of Captain Bellevan, escaped into Port-de-Paix.