I note the HMS Prince if Wales has two superstructures. This, while those of U. S. carriers, which have one, are shrinking (referencing the new Ford class vs the Nimitz class ships).
Anyone have any insight into why the Brits use two?
I checked the Wiki page for Queen Elizabeth-class aircraft carrier since the HMS Prince of Wales is the second of that class. Wiki has this to say about the dual islands:
Instead of a single island superstructure containing both the ships’ navigation bridges and flying control (flyco) centres, the ships have these operations divided between two structures, with the forward island for navigation and the aft island for controlling flying operations.[49] The primary reason for having twin islands was to space out the funnels, as the ships were designed with redundancy with “duplicated main and secondary machinery in two complexes with independent uptakes and downtakes in each of the two islands”, while the alternative of consolidating all the exhaust trunkings would have reduced hangar space as well as increasing the vulnerability to flooding. Additional benefits include easier construction, reduced wind turbulence, and freed up deck space. Using two structures provides separate mountings for the air surveillance radar (forward), which does not interfere with the medium-range radar (aft); furthermore, visibility is improved for both navigation and landing operations.
I left in the links.
The Reason the HMS Queen Elizabeth has Two Islands:
Many have wondered why HMS Queen Elizabeth has two ‘islands’. Here we consider why she is the first aircraft carrier in the world to adopt this unique arrangement and the benefits it brings.
Redundancy and separation can be good
In a moment of inspiration back in 2001, an RN officer serving with the Thales CVF design team developing initial concepts for what became the Queen Elizabeth Class, hit upon the idea of separate islands. There are several advantages to this design but the most compelling reason for the twin islands is to space out the funnels, allowing greater separation between the engines below. QEC has duplicated main and secondary machinery in two complexes with independent uptakes and downtakes in each of the two islands. The separation provides a measure of redundancy, it increases the chances one propulsion system will remain operational in the event of action damage to the other. Gas turbine engines (situated in the sponsons directly below each island of the QEC) by their nature require larger funnels and downtakes than the diesel engines (in the bottom of the ship). The twin island design helps minimise their impact on the internal layout.
In a conventional single-island carrier design, either you have to have a very long island (like the Invincible class) which reduces flight deck space or, the exhaust trunkings have to be channelled up into a smaller space. There are limits to the angles this pipework may take which can affect the space available for the hangar. The uptakes can also create vulnerabilities, the third HMS Ark Royal was lost to a single torpedo hit in 1941, partly due to progressive engine room flooding through funnel uptakes.
The forward island is the navigation bridge, the aft island is for controlling flight operations. The article also discusses other benefits, such as reduced air turbulence over the deck.
Well, it’s all academic as it is now broken.
The two British superstructures contain the two funnels, aiding in redundancy. American carriers are nuclear-powered, and do not have funnels.