Hello folks. I am currently working with a French guy who is a retired sonar analyst on their boats. We got chatting the other day and I mentioned that I have had in a previous job a few weeks riding s and t boats here and there for reasons I won't go into now. He asked me a question I don't know the answer to. Do RN submariners have an offical log of time spent underwater? Apparently in the French navy they have a "dive book" with everything logged. He has an old colleague with rather a lot of time dived and wondered if there could be a way of establishing the world record. What do you think?