My partner and I were talking about this case the other day. He grew up with boats, got his first boat years before his first car - but he’s used to little day boats/ribs you use to get from a to b or go fishing, his mum and aunt and uncle are the ones who sail in sailboats/yachts.
I gave him an outline of the description of what the boyfriend said happened. My partner, although admittedly not familiar with this type of boat or anchor alarms, said if he heard the anchor alarm and I wasn’t on board he would assume I had gone over and was either struggling to hold onto/climb the chain in strong currents or had been messing about with it (ie pulled it up) and got caught in it as it’s gone back down. He said the first thing he would do in that circumstance is call out for me. If he didn’t hear a reply he would have had a torch out and the anchor up to check it wasn’t me setting off the alarm. Then he would have called the coastguard and roused other boats/got people out searching the bay by torchlight in their dinghies. He not once said that calling the police would be high up on his emergency checklist - the coastguard would be the first point of call and a massive priority (in his home country anyway). They are the ones with the resources to properly search at sea.
He is not a trained/professional sailor, so this explanation may vary a bit from proper protocols, but where he is from boats are a way of life and I figured his thoughts may provide another what would a ‘reasonable man’ do? type approach to measure against, especially considering the boyfriend is supposed to be a captain by profession.
The main takeaway I have from what he said (and he said this is hugely suspicious to him) is that NOT calling the coastguard until 10 or so hours later in a MO situation is super weird. If you wanted the missing person to be found you would call the coastguard ASAP, not leave it until after you’ve had a good nights sleep, breakfast, and done your morning chores!! JMO, of course.
Upthread, someone mentioned sharks. In the first days I thought that was a possibility, especially with the reported scream - could have gone overboard, been splashing/swimming and attracted a predator, was attacked and killed by the shark or drowned as a result of injuries sustained during it. I may be wrong, but I believe bull and tiger sharks are in that general region, and the former certainly hang around shore areas (they can even tolerate freshwater and go up river/hang in estuaries if I remember correctly) and the latter I recall to be nocturnal predators. Both species have been known to attack people.
Then I found the bay on Google maps. it looks to be really quite shallow, the waters are transparent, and it looks to be largely sandy bottomed rather than reef. I mention this as sharks tend to hunt, when they can, where there is an abundant food source - if there are reefs in the area it’s more likely they would cruise/hunt in those areas. Also, controversial as this may be, there is quite substantial support for the idea sharks are not generally man-eaters, they attack thinking we are a plump blubber-filled seal and having had a taste bite they usually leave the rest, because we don’t taste like what they were expecting. Unfortunately, the taste bite is often fatal. I raise this as I think, in those crystal clear waters, if she had fallen off the boat and been attacked by a shark there would be clothing, or other remnants, visible where they sank. I also think the dog walker would have heard multiple screams and thrashing water if that was the case.
If Sarm went overboard farther out to sea then that theory falls flat, it’s highly unlikely that any remains or evidence would ever be found - shark or no shark.
I would note that I am an avid scuba diver and, having said all of the above, I would never now go for a twilight or night swim in bull/tiger (and other) shark areas regardless of where I figured their hunting grounds were likely to be! Until you night dive you don’t realise how lively things are down there at all hours of the day and night!
As ever, all the above is JMO, but been lurking and figured I’d add my thoughts! Very much hope Sarm is found safe and well, but sadly feel at this stage it is unlikely and we may instead have to focus on justice being served. My biggest concern with this case, which seems to be shared by fellow sleuthers, is that at present there is only the circumstantial suggestion of a crime - not the hard evidence needed for a court of law. For the sake of Sarm’s friends and family I hope the truth emerges and they are able to get some measure of closure.