I didn't say anything about water temp in Hayama in February. I said I didn't dive there in February.
How many times did you dive in Tokyo Bay in February? I mentioned Tokyo Bay only as a reference, because it's near, although, I wouldn't be surprised if water temp was a little warmer in Hayama than Yokosuka.
I did two dives at Ita Beach (Suruga Bay) in Izu on 2 February and the temp was 58F (14.4C).
17 February I dived in Tokyo Bay and the water temp was 47F (8.3C) (why do I need to repeat myself?).
Water temp in Izu. has nothing to do with Tokyo Bay. Completely different body of water. Water temp will always be warmer there than Tokyo. Take a little time to think about it and I'm sure you can figure it out
When I fill out my dive log, I do just what everyone else does. I read the data from my computer and I enter it in my log. I'm sure Bill will accept my data as accurate and that was who I wrote the post for.