The were tripod mainmasts in all, and a tripod foremast in the HMS Inglefield.
All of the "I" class had pentad (5) torpedo tubes on each launcher. The HMS Inglefield had the penta torpedo launchers changed to quad launchers in 1942 and 50 tons of ballast was added.
The extra torpedo tubes, compared to prior classes, caused the "I" class to be top heavy and not as stable. A casing over the engine room was removed to help with stability.
The "I" class was designed to be converted to minelayers. When converted, the 'A' and 'Y' guns, torpedo tubes, and TSDS (two speed destroyer sweep) minesweeping gear was removed. Only the Icarus, Impulsive, Intrepid, and Ivanhoe were converted.