It's a language thing. The "if need be" on the end of my sentence indicates that the 'winching' is not a normal occurrence but rather that "if it really hits the fan" during a dive then I should be able to winch myself up should I have no other option.
I suppose that "if it really hits the fan" might be another language thing? No, I'm sure that "sh*t hits the fan" was an import into the UK.