The masts are so high in the first picture that if there was a sub there they would risk striking the sail on the bottom of that patrol craft.
Now on to the RN Carrier being sunk. The whole thing probaly came from an Argintine attack on the hulk of the Altantic Converyor which was deployed as a decoy for the RN Carrier TFs. The AC was a big ship with a retlivly empty deck with a few discarded aircraft (from the prevous Exocet attack) so its easy to see why a pilot flying a high speeds while being shot at might think it was a carrier.
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