A few observations on this:
- the helmsman had a breath/alcohol concentration of 74mcg/100ml (road driving limit 35/100). This was back calculated to the time of the accident and estimated to be ~3 x the road limit (so impliedly ~105/100)
- the deceased crew had blood/alcohol concentration of 264mg/100ml (road driving limit 80/100) so he was also ~3 x the road limit
Yet the helmsman (reportedly) had not consumed the same amount
The coxswain ... only consumed alcoholic drinks on alternate rounds
There is no direct reference to the lunar phase. There's a massive difference between navigating at night with a half moon or better (even with cloud cover) and no moon.
What part (if any) was played by the tinted windscreen and/or the canvas canopy with clear plastic sections (this may have been rolled up out of the way, I'm not certain)? On a moonless night in confined water, I find it essential to get my head in the open air. I wonder if this played a part.
The effect of the deck light (apparently switched on) is mentioned and is in my view very significant. Even if it was switched off when they left the mooring, the white light from a few minutes earlier would have delayed/prevented the development of night vision for some considerable time. Even without that, it is easy, in an open boat, for night vision to be affected by the all round white light.
It seems quite likely that alcohol played a part in this accident. I wonder if the combination of moonless night, glare/night blindness from the deck light, no adjusted night vision and tinted windscreen meant that the helmsman, for practical purposes, may as well have been wearing a blindfold.
Don't 'drink and drive' is fine as far as it goes, but the direct cause of the accident, it seems to me, was the fact of navigating in the dark, at speed, without actually being able to see. That's simply dumb regardless of intoxication level.