Unfortunately I'm not sure these weapons were available during the time period I am looking at i.e. September 1940. I may be wrong, but I thought these were only available from 1942 onwards?One thing that Royal Navy ships at that time were vulnerable to was chemical weapons. Chemical weapons had come a long way since WWI. They weren't all gas and they don't all dissipate. An agent like Cyclosarin (GF) is a liquid, not a gas, and it does not evaporate. It is also extremely potent. Contaminate the decks of a ship with GF and the crew cannot safely venture on deck to operate the weapons systems even if the crew still has effective control of the ship's power from below. Properly clothed boarders cannot be repelled either. GF can be mixed with binding agents from corn syrup to glue to paint bases to make it difficult to clean off of a surface and decontaminate it.