Wookie: Can you describe your method for making sure everyone is onboard and what channel you want to monitor for divers that have a Nautilus Lifeline (default is channel 8).
Regarding non-safety features, a diver’s elevator like some of the boats in the UK would be nice.
Sure. All divers are checked off the boat by their bunk number. As they re-board, they are asked for their max depth and bottom time. This is not necessarily to nanny them, but in the event of an accident, I have a record of their dives, especially if they don't use a computer. So, first check of back onboard is by a questioning divemaster. Then, the captain does what's called a "welfare check". Every diver is looked in the eye and asked how they are feeling. It's amazing how many divers will look you straight in the eye, and with one eye twitching like mad tell me that they are fine, or as they rub their shoulder, or their hip. We had one girl lifting her leg to go over the knee knocker as she came in and out of the house. If a diver has made a dive, they are woken up for every welfare check regardless if they made that dive or not. If a diver has stopped diving for 24 hours, or a guest is a non diver, we just verify that they are physically present, but don't necessarily wake them up. Additionally, before I move the boat, I look for a snorkeler/swimmer in the water and for missing gear on the dive deck.
This accomplishes a couple of things. The captains learn the names of every diver (you can't just call them "bunk 11" for the entire week), the divemasters learn the name of every diver, and the cooks learn the name of every diver (can't be helped, folks like to hang out in the galley). It's interesting. Every liveaboard I've ever been a passenger on has had a place that is off-limits to the passengers. One boat captain went so far as to tell us during his briefing that "it was the only place that the crew could get away from the passengers". Everyone who comes on the Spree is a Guest or a Customer, the only place they are referred to as passengers is in the logbook, because it is a term required by the Coast Guard. No place on the Spree is off limits to our guests, although some places require an escort. If you want to inspect my bilges and thru-hulls, you are welcome to do so.
Regarding boarding elevators on dive boats. The Coast Guard takes special interest in elevators that can carry personnel. It's kind of like a hot tub. You'll never see either one on the Spree.
Spree always stands by on 16 and 19. If I used a Lifeline, I'd have it on 16, the "international hailing and distress frequency". 8 around here is where the pilots chat privately.