My team alerted me to this. Apparently the RN records they have used came from them. Ah, fame at last .
Actually the more I learn about my job the more I realise I don't know. I'm a surveyor. I measure things. But the oceans are far more volatile than I ever cared to realise - with salinity, sound velocity, temperature, turbidity etc. It's not just about depth. It's about all the environmental factors that impact you - that' s what counts.
I figure that I'll perhaps know what I'm talking about when I'm 80. But I wouldn't put money on it.