The extra weight of the torpedo tubes and the fitting of minesweeps and depth charge gear (previous vessels carried one or the other) on the same hull as the H class, caused a loss of stability, needing ballast when bunker levels were low.

All ships were fitted for minesweeping and with depth charges and Asdic for anti-submarine (A/S) work and were capable of conversion to minelayers.

Radar Type 286, a metric wavelength surface-warning set, was added as it became available and the ineffective multiple 0.5 in (13 mm) Vickers machine guns were replaced with Oerlikons; the central tube was deleted from the torpedo launchers to lessen topweight.

Surviving ships received a third pair of Oerlikons, added abreast the searchlight position and the 12-pounder was deleted to increase depth charge stowage.

Inconstant later received Type 270 radar, a centimetric wavelength target-indication set, in place of the director and rangefinder on the bridge.