Why aircraft carriers place the island to starboard

Why are aircraft-carrier islands usually on the starboard side?

Propeller torque made many aircraft easier to roll right, and rightward movement was also more natural for pilots, so starboard placement supported predictable avoidance behavior.

Flight-deck design has to anticipate the way aircraft and pilots respond when an approach goes wrong. Engine torque made many aircraft easier to roll to the right. Rightward motion is also more natural for the pilot's hand and body. Placing the island to starboard works with those tendencies rather than putting the main obstruction across the expected escape path.