I would like to interject my 2 psi. A crew should know, no matter how experienced the divers are or aren't, vigilance in keeping watch is paramount. We recently ran to the Aeolus, an artificial reef that was torn in 3 by a hurricaine. Vis was down to 15 ft, I hooked us to one of the radiators between the stern (15 feet away) and the amidships wreckage. I did my dive, the stern had about 20 feet of vis, maybe a little more. I came back to where the anchor line should be, couldn't find it. Once I finally did, I ran my deco obligations, and surfaced, hoping to give a warning that vis had deteriorated to 10 feet or less, and we might want to keep en extra watch. So, even though our guests were highly experienced, we took places allowing ourselves to veiw the sea in all directions. Within a minute, we had a liftbag from one of the divers. With the current running on the surface, we sent a swimmer to pull the diver back towards the boat. Our diver had been unable to find the anchorline. Now, he is a trimix instructor, one of the best divers I've seen in the water, and he managed to need the crew's assistance. Even without the extra watch, we probably would have spotted him, but, the point is, as a crew member, going below for anything other than an emergency when divers are in the water is just un-professional. I would personally never set foot on a boat that did that. Because sooner or later, no matter how good a diver you think you are, no matter what your training, buddy, gear, etc, you could find yourself in a situation beyond your control, at the surface, drifting from the boat. Just my experience, thoughts, and off gassing.
-J
-J