Late WW2 WO titles query

[Skipperino]

Hi all; I've been doing a spot of research on the RN during the Second World War and there are several abbreviations for warrant officers' titles that I'm not familiar with; I just wondered if anyone out there with more knowledge than me could help me out here.

First; 'Boatswain (F/F)'...I'm guessing fire fighting, but I can't find an explanation of what it stands for. Second, 'Boatswain (C/M)' Controlled mining? I have no idea.

Any help gladly and massively appreciated.

 

[Dusty70]

https://en.wikipedia.org/wiki/Boatswain

Firefighting sounds good
carpenters mate might be the other