Recall divers ?

[Pyromaniac]

Ok - in the new diver forum is a topic on does rain affect diving - and one thing bought up was - what weather conditions might cause a dive to be cancelled.

My question is - if all the divers are down, and then the surface conditions degenerate such that the boat (if using) has to move - or cant hold its anchor, or anything like that-

How does a boat recall the divers and/or make them aware they need to surface and be picked up ?

Or cant they?

 

[Dive-aholic]

The typical method I've seen used is to rap a metal pole against the boat ladder at a moderate steady pace. This can usually be heard by the divers in the area. Just make sure all divers are briefed on the recall system.

 

[Jedderkoppen]

One way, that was used by a friend of mine on some dives, was just to rev the boats engines. because we were usually the only boat on the site, if you heard the reving of a boat in a pattern, then you knew it wasn't a passing boat, but a recall.

never was called back because of visibility though ...

Cheers,
JE

 

[victor]

I was caught out sailing a small cat in a line squall in the med. The weather went from lovely sunny light winds to close to gale force in less than 5 minutes. Very unpleasent indeed.

If we had been diving then the boat would not have been able to pickup divers safely. With the strong winds, very heavy rain, and short steep seas trying to get divers back on to a ladder would have been very difficult.

 

[Damselfish]

whatever boat you are on, they will (or should) tell you this as part of a briefing.

 

[Charlie99]

I was caught out sailing a small cat in a line squall in the med. The weather went from lovely sunny light winds to close to gale force in less than 5 minutes. Very unpleasent indeed.

If we had been diving then the boat would not have been able to pickup divers safely. With the strong winds, very heavy rain, and short steep seas trying to get divers back on to a ladder would have been very difficult.

Squall lines and thunderstorms, however, tend to be short lived events. If the weather hits suddenly, then there's a good chance that it will also leave suddenly.

Immediately surfacing is NOT always the best idea, particularly if you are on a drift dive.

I've been diving in SE Florida where suddenly it seemed like someone turned out the lights, and we went from a light current at 80' to 2 or 3' surge back and forth. When we surfaced 30 minutes later, however, it was bright and sunny again, with just a bit of wind wave from the squall left over. Surfacing into the middle of the squall would have been a very bad idea, since the Captain said that the viz had dropped to just few boat lengths and finding divers on the surface would have been extremely difficult.

-------------------

As for recall methods, many boats use the "knock three times" repeatedly on a ladder, or multiple revs of the engine. That may or may not work.

The high class boats have an underwater speaker that the can lower into the water ---- it can generate the typical cop car / fire engine / ambulance siren sounds. Even if it were not covered in the briefing, I'm pretty sure that most people would figure out what's going on when they hear the very loud siren underwater. I've seen one that also works as an underwater microphone --- pretty cool for listening to the humpback whales off of Maui.

 

[Doc]

Grenades.

 

[Charlie99]

Grenades.

Actually, for many years a one way method of surface to submarine communication has been a thing called SUS. "Signal, underwater sound" devices are kind of like an underwater M80 firecracker. When in the Navy, I've used those to signal a submarine that we were conducting exercises with. And when we had repeated duds when trying to send a signal of 3 booms, pause, 3 booms, we went to concussion grenades instead. Very reliable. Much more powerful.

Unfortunately, I forgot to tell the engine room. My Gunner's Mate was chucking them as far as he could while on a 36' eye height bridge, but they were still so loud down in the engine rooms that they thought something had blown up inside the engine room, had declared an emergency, and were frantically searching for the failure before I realized what happened and sent word back down that we were using grenades. It took a couple days before they could see the humor in the incident.

 

[Thalassamania]

We also used M-80s and cherrybombs as well. For an interesting study that touches on many diver recall devices take a look at: Non-Lethal Swimmer Neutralization Study. At the bottom of page 41 is a discussion of M-80s.

 

[victor]

Squall lines and thunderstorms, however, tend to be short lived events. If the weather hits suddenly, then there's a good chance that it will also leave suddenly.

Immediately surfacing is NOT always the best idea, particularly if you are on a drift dive.

I've been diving in SE Florida where suddenly it seemed like someone turned out the lights, and we went from a light current at 80' to 2 or 3' surge back and forth. When we surfaced 30 minutes later, however, it was bright and sunny again, with just a bit of wind wave from the squall left over. Surfacing into the middle of the squall would have been a very bad idea, since the Captain said that the viz had dropped to just few boat lengths and finding divers on the surface would have been extremely difficult.

Yes the storm only lasted about 30 minutes, but the sea was rough for maybe another hour.
If you had been on the surface during the storm it would have been extremely uncomfortable. The rain was hard enough to hurt. Many would have been seasick. The boat would just be a liability as
1, they could not see you and might run you down
2, getting onboard would have been very dangerous
3, easy to get seperated from your BC while trying to get on board.

If you knew what was happening you could get the group together at 15 / 20ft just below the surge and hang there until the weather improved. Put up a couple of sausages for the boat to home in on. Then wait it out. Of course this requires everyone to have loads of air left.

I was wondering if this is covered in the divemaster / rescue courses as a scenario. And if so what was the recommended solution. :classic: