This is a terrible tragedy for the SoCal dive community. I'm not sure yet if I know any divers on this trip.
I have been on the Conception overnight a number of times, the last time being January 2019. It is a really nice boat. The owner, Glen, runs a good operation. The crew is good. The bunk area is not that crowded, many dive boats have more narrow aisles. The stairs are narrow but easy to go up and down, they are stairs not a ladder.There is an emergency ladder exit at the back of the bunk area which is always mentioned in the safety briefing. As others have said though the briefing is usually the first morning after motoring to the island overnight. I could see that changing where they require you to be on the boat a certain time before departing and the briefing is given before departure. I think this was a three-day trip, Saturday, Sunday and Monday, so they would have had the briefing Saturday morning and would have completed the first two days of diving.
This looks like it was a mini explosion that overtook the boat instantly without any time for anyone, crew or passengers, to react. Lost of possibilities how this could happen between engine, generators, cooking facilities and clothes dryer. And with multiple confined space below deck lots of possibilities.
I am scheduled to go on the Truth, the first of their three boats, in two weeks. Glenn the owner was to be the captain for that trip since we were going to go where they don't usually go, up past Point Conception. I suspect that trip will be canceled as the company will be busy with this tragedy and likely a complete safety review of their other two boats, Truth and Vision, and all their procedures.
I wouldn't hesitate to go out again overnight on a Truth Aquatics boat. Prayers for the owner, Glen, all his crews and the divers and their families. This is really sad.