They are HF radio masts that are hinged down for flying operations.
My initial thoughts they were radio direction finders or airframe recovery booms, but my research does not support it.
In port they are up. With planes in the air, they are down. Four port, four starboard. Two forward, six stern. They are connected by cables.
Deployed as vessel was sinking (Higher quality image). You can clearly see end curves down towards water. Deployed they are below flight deck. Clearly seen from YouTube video With The 'ark Royal' (1940) as a plane takes off.
They are substancial as seen from YouTube video HMS Ark Royal - 14 de Noviembre de 1941.
The timing is around when Radio Direction Finding was introduced (which is why I answered the question) and RDF was used by the HMS Rodney supporting the Arc Royal. The Arc Royal was built before the Illustrious.
From: Radio Location Goes to Sea - Chapter 2 of Radar and the Fighter Directors
The new-construction carrier HMS Illustrious was commissioned in April 1940, and would be the first RN carrier to have RDF. Later, while exercising with her air squadrons off Bermuda, Illustrious tried using RDF to guide fighter intercepts. HMS Formidable would be the second RN carrier to have RDF, commissioning in October 1940.
These antennas are common to carriers. The next Arc Royal and the Illustrious have them too. All carriers of the period and later have them.
From Essex Class Aircraft Carriers of the Second World War
Lexington (CV-16) ... SBD Dauntless dive-bombers are marshalled at either end of the flight deck, and the radio masts are hinged down for flying operations.
anyone serve on an aircraft carrier or in the know about them?
I served as an electronics tech onboard the USS Nimitz for three years and those were my babies. Those are two piece 35 foot HF whip antenna. They are in the down position during flight operation (and generally when underway) to keep jet wings safe. They are manually lifted when in close confines. They have nothing to do with HFDF or fall arrest.
And finally, you can trust the model world because they really do do their research.
Sketchfab 3d Model of Arc Royal.