Would You Use a DSMB in this Scenario?

[xyrandomyx]

Take this hypothetical scenario:


You're doing a drift dive with a group. There's a DM/ dive leader towing a static SMB. The current's < 2 kts. The plan is to dive as a group: ie. the dive will be aborted if anyone (on their own or with their buddy) is missing for more than a minute or so. Boat traffic is not a concern. You and your buddy somehow get separated from the group.


Would you shoot a DSMB from depth? From safety stop depth? Or only deploy it on the surface (if necessary)?

 

[Tigerman]

If separated from the group and carrying a DSMB, shoot it. If theive surfaced and look for you, seeing the smb is MUCH easier than seeing your head.
Better shoot the smb too often than not often enough..

 

[farsidefan1]

Depends on how much practice you have had shooting form the depths. If you are already feeling a bit stressed due to "separation anxiety" I'd just surface and shoot it. On the other hand this is a good reason to practice shooting smb from depth when under a more controlled environment. If you are in a low boat traffic area it isn't a big deal. In big waves and where I and my buddy have been doing our own thing instead of following the heard I've often done it on the surface.

 

[PfcAJ]

I'd probably shoot it from depth in that case, esp if the boat isn't expecting you to separate from the group. Shooting it early increases chances of them seeing it (since it'll be close to the DM's float) and they can track it if you move farther away.

 

[xyrandomyx]

If separated from the group and carrying a DSMB, shoot it. If theive surfaced and look for you, seeing the smb is MUCH easier than seeing your head.
Better shoot the smb too often than not often enough..

That was my first thought, but I started to question myself: shooting a DSMB takes time; and the longer you're separated from the group, the further you're likely to be separated. How long does it take me to deploy a DSMB? I'm not sure. It's probably a good idea to time myself at some point. I haven't had much practice, though, so three minutes (or maybe even more?) wouldn't surprise me that much. I'd be very surprised if it took much less than a minute. So, if I'm ascending from a depth of ~100' (which is considerably deeper than any drift dive I'm likely to do in the near future), it'd take me about 3.5 minutes to get to the surface without a safety stop.

Is adding, say, two minutes to that to shoot a DSMB from depth worth it? I'm thinking 'maybe, particularly if the current nearer the surface is different from the current at depth (as it often is)'.

 

[ermaclob]

i would disagree to that pre dive briefing. the bigger the group the more likely separation is going to happen. dive teams of 2 or 3 people max for me. solves that problem right up.

but in your situation yea shoot the SMB.

 

[Rogersea]

Really depends on your depth, with the dive plan you described, and provided you are competent deploying the Surface Marker Bouy at depth, I would shoot it from depth. This allows the group to have more of a chance "re-grouping and continuing on the dive.

On a related note, skills like deploying the SMB from depth should be practiced. My DM (Jo An) can shoots hers in a little under a minute. I typically deploy it at Safety Stop depth but sometimes practice it at deeper depths(usually 15M or 50 Ft) if I have briefed the boat crew before hand(to ensure they know we are not experiencing trouble) since our dive style dictates the boat pick us up if we are shooting the SMB.

Cheers,
Roger

 

[MXGratefulDiver]

I'd shoot the bag.

Then again, I doubt I'd agree to a "group" drift dive in the first place ...

... Bob (Grateful Diver)

 

[Colliam7]

You're doing a drift dive with a group. There's a DM/ dive leader towing a static SMB. The current's < 2 kts. The plan is to dive as a group: ie. the dive will be aborted if anyone (on their own or with their buddy) is missing for more than a minute or so. Boat traffic is not a concern. You and your buddy somehow get separated from the group. Would you shoot a DSMB from depth? From safety stop depth? Or only deploy it on the surface (if necessary)?

Shoot from depth.

Comments:

1. Shoot from depth so the boat and the rest of the group group have a chance to locate you as early as possible. They will possibly / probably see your SMB, know where you are, and can wait for you to surface - or vice versa (since that was the plan in the event of separation). You didn't give details of the hypothetical dive beyond the plan in the event of separation. So, I am not sure whether there was a boat involved, or if it was a 'shore-to-shore' drift. Presuming it was a boat-based drift, boats are going to try to follow bubbles, if possible, and/or the surface float (if bubble tracking is hard / not feasible). Shooting the DSMB will let the boat know that separation has occurred.

2. Definitely time your DSMB deployment the next chance you get, and practice the skill if it takes more than a minute, until you can shoot the DSMB proficiently - should NOT take more than a minute, and should be less than that. In any event, practice deployment while neutrally buoyant. That way, you would be continuing to drift as you shoot the bag, presumably in the same direction as the rest of the group, so separation should not necessarily grow larger.

3. This is also a good discussion to allow you to actively participate in a drift dive briefing, as it is a good question for the drift leader / DM.

In a case like this, like Bob, I probably would be reluctant to agree to (part of) the plan as stated, anyway - the 'group' drift dive. Unless there are some tricky currents, I would prefer that the group should be viewed as a set of buddy teams, operating with some independence - as long as each buddy team has a SMB of some kind. Even if a buddy team gets separated from the larger group, if they continue to drift, they should end up in just about the same general place and a boat used to following drift dives is also used to picking up divers sequentially, so it should not be a problem.

At the same time, I also can appreciate a DM's preference that the dive be aborted in a buddy pair gets separated. That is better group control (for the DM). But, it can also constrain divers, particularly in relatively low viz. In the Caribbean, with 80 ft of visibility and a calm surface, it isn't a big deal. The leader can brief the dive so that buddy teams surface after a certain time, or when one diver in a team reaches a certain gas pressure, and the boat follows along and picks them up as they surface. But, they can spread out and the leader still has most / all in view. In lower viz, if one buddy team wants to stop and examine something, they can quickly lose sight of the rest of the group, and a plan that calls for surfacing in that event means each team either has to keep up with the group, or the dive ends early for everyone.

 

[idive2]

I dove a few weeks back in a guided dive type arrangement. Our group started with about eight to ten divers.
When all was said and done only three divers from the group ended up under the original float carried by the
guide. Anyone diving on a guided dive needs to know the guide is NOT your buddy and you really need to have
your own buddy within the group. If you are not experienced with deploying an smb I would maybe wait till
a slightly shallower depth, maybe 20 feet or so. Deploying at depth gives you the bonus of extra air in the smb as it
surfaces but it is a quick ride up from 50-60 feet if something goes wrong. If you surface before inflating be very careful
and look and listen for boat traffic when you get near 20 feet or so of surface. Did I mention the guide is NOT your buddy !
Last statement not directed at original poster just something anyone diving a guided dive really needs to know !