The Lochs were based upon the hull of the preceding River class with increased sheer and flare to improve seakeeping and modified to suit it to mass pre-fabrication, with sections riveted or welded together at the shipyard.

Accordingly, as many curves as possible were eliminated, producing a noticeable kink in the main deck where the increased sheer forwards met the level abreast the bridge.

The ahead-looking ASDIC (sonar) set lost contact at the vital moment before the weapons were launched, allowing a skilled submarine commander to take evasive action.

The increased weight of the stabilised antenna array and the carriage of HF/DF at the masthead meant that a lattice mast was stepped in lieu of the traditional tripod or pole.

As with the previous wartime escort designs, mercantile machinery was adopted to speed construction, with a pair of 4-cylinder vertical triple-expansion reciprocating engines.

Due to a need in 1944 for a version fitted as anti-aircraft vessels with the British Pacific Fleet, twenty-six units were authorised for completion to a modified design labelled the Bay-class frigate and were renamed.

With the war in the Atlantic won by 1944, and a need forecast for additional fleet A/A escorts for the Royal Navy's increased Far Eastern commitments, twenty-six Loch class were redesigned and renamed (of which nineteen were completed) as Bay-class anti-aircraft frigates.

Loch Killisport sported a gunshield manufactured from GRP to test this material for suitability of constructing the housing of the new 4.5-inch gun Mark 8.