Explained: Why the Island on Aircraft Carriers is Mostly on the Starboard Side?

Last updated on October 18th, 2021 at 11:26 am

Have you ever noticed that almost all aircraft carriers have their island on the starboard side? We used ‘almost’ because there are two exceptions – The World War II Japanese carriers Hiryu and Akagi, sunk at the Battle of Midway, had their islands on the port side.

So what is the reason behind placing the island on the starboard side of the carriers?

Well, we can safely say that H.A. Williamson, Flying officer on the Royal Navy’s HMS Ark Royal, is the father of the current design of carriers with an island placed on the starboard side.

Williamson first proposed the idea of an aircraft carrier with an island and a form of arresting gear in 1915 for HMS Argus. In his detailed designs, Williamson placed the island on the starboard side because Single-Engine Piston Aircraft had a natural swing to the left side (port side).

The propeller of most of the engines, at that time and even now, rotate clockwise with respect to the pilot’s position, and the torque effect generated by the propeller makes the body of the plane swing to port. Pilots have to counter this effect, particularly during the take-offs and landings.

Hence Flying Officer Williamson’s design had the island on the starboard side as it was logical for an approaching aircraft to circle in from the left, and during touchdown, if it failed to arrest, to fly off to the left (due to the natural swing of the aircraft to port).

Unfortunately, Royal Navy rejected his idea. The first full-deck aircraft carrier, HMS Argus, was completed in 1918 without a superstructure. As Royal Navy’s experience with Furious, which, in her original carrier configuration, had an immense superstructure in the centre of the flight deck, showed that turbulence was a significant problem for landing aircraft.

As Argus had a flush deck, she was controlled from a retractable chart house in the middle of the flight deck forwards or from ‘wings’ on either side of the flight deck forwards when the chart house could not be used. Smoke was carried away from the boilers via ducts that ran through the hangar and out of the ship’s aft. This arrangement proved to be unsatisfactory, turning the hangar into an oven and making approaches difficult. For future designs, the Royal Navy began to examine the use of single islands, and that’s when the Royal Navy realized their mistake of rejecting Williamson’s idea.

Inspired by Williamson’s design, HMS Hermes – the first proper aircraft carrier, designed and built from the keel up as an aircraft carrier, not a conversion – and her sister ship HMS Eagle, had islands on the starboard side.

Once Royal Navy understood the logic behind placing the island on the starboard side, the design was standardized, and since then, all navies built their carriers with an island (or islands!) on the starboard side.