is the boat going backwards ? the chap at the helm in blue looks like he's facing the stern. also looks to be some turbalance in the water from incoming water.
The lights are aligned horizontally, and were obviously not fully visible from deck level. I think the skipper assumed that because the cill was opened a few moments before, it was safe to dash out.
ooops, large CLANG sound, and he was swept back into the inner harbour. A second try a couple of minutes later was OK.
There's local warning from the staff to give the incoming current a good fifteen minutes to settle after the cill is lowered. The harbour is Watchet yesterday pm.
Perhaps the shroud round the lights might be opened a bit at the bottom ?