Yeah, I did a quick check myself and couldn't easily pull up any accurate info on the depths in that area either (though, from what I did find, they might tend closer to 100m) 30m is about 100 feet, and that's where it can start to kick in for some people. With trained divers for the Foundation, they'd probably be feeling it around 150, but be able to cope. But using different breathing mixes can prevent the effect, so that part is actually okay.
Diving solo is a no-go for recreational divers. Occupational divers, on the other hand, spend most of their time in the water alone. Not really sure what Search and Rescue protocols are on that regard, though.
Occupational dive crew must have at least 3 people: Diver, Standby Diver, and Tender. Diver's role is to be in the water and do the work. Standby diver's responsibilities (only) include being ready to dive in an emergency, and maintaining communication with the diver. Tender does any other work required on topside, and assists the Standby Diver to get in the water in an emergency.
Two divers can dive at the same time, acting as standby to each other if communication with a diver on surface would be difficult or impossible, though they need a means of contact with each other in the water (I've heard 'visual contact' argued as adequate, though that's kind of a joke for an open water scenario)
For this line search operation a single diver, communicating with a tether line, would work like so:
- After positioning the vessel and determining the search area (probably a 180º arc off the stern) the Diver gets in and swims to the end of their line, marking the far end of their search area.
- The Standby Diver uses a predetermined set of line pulls to communicate with the Diver (i.e. 2 pulls = face the line and go to your right, 3 pulls = face the line and go your left, 4 pulls = come to surface, etc.) and guide them. When the Diver reaches the end of the arc, the Standby signals them to turn the other way.
- The Diver works his way back towards the boat (number of passes required depends on visibility) until he finds his objective or is back at the boat.
- If Diver finds it, he signals the Standby and they mark the co-ordinates. If not, determine a new search area and repeat the process.
I'll grant there are some industry regulations that Foundation would skirt around, but those would be for pragmatism and secrecy. If a couple-hundred feet of rope does the job to the same standard as a more expensive radio technology solution, the rope is going to be the preferred solution.
On the whole, if the general area the SCiP roams were a bit closer to shore it probably wouldn't hurt. But the procedures are actually reasonably explicable otherwise.
(account deleted)
