Would You Use a DSMB in this Scenario?

[DivemasterDennis]

Good question, and good discussion. Varying factors may dictate whether you deploy at depth or at the surface. Either is ok in my book, but I would deploy from depth if there were no stress factors and I was "good at it."
DivemasterDennis

 

[xyrandomyx]

Thanks for all the replies.


OK, so it seems the consensus is 'deploy the DSMB from depth', with two disclaimers:


a) you have to be proficient at it; and
b) the hypothetical plan I described is possibly not a good idea.


As for 'a': I need more practice, but I am practicing (in non-stressed circumstances where it's not a necessity), so I will presumably get there soon enough.


As for 'b': I based my hypothetical plan roughly on the couple of drift dives I've done before (all at the same location, from a boat). It was a 'group dive' in the sense that the plan was to stay roughly together with the guy towing the float, but there were clear buddy pairs (who were free to ascend when they liked, or generally move around in reasonable proximity to the guy with the float).


I didn't, at the time, consider asking if my buddy and I could tow our own float or continue diving and shoot a DSMB at the end in case of separation from the rest of the group.

---------- Post added December 7th, 2012 at 06:25 PM ----------

<snip>

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.

<snip>

In general (not talking drift dives in particular), I quite like diving in a small-ish group as long as I have a clearly assigned buddy. But not a group where no-one is anyone's buddy. I don't mind if I have to cut a dive short because a buddy pair were separated -- but I can see why you (and many others) would, and maybe that'll change in future. And, yes, it obviously constrains buddy pairs (to varying degrees depending on the size of the group and conditions) -- again, I don't mind, but get why others would. I do, however, mind (in a big way) if I'm relying on sticking with the group for safety (it's gonna happen at some point) -- at the least, I've got to have a way to safely end the dive if my buddy and I get separated.

Anyway, all of this is hypothetical for now. I was really just wondering -- aside from proficiency in deploying a DSMB (something that can be rectified) -- if there was a reason not to shoot it from depth in this kind of situation.

 

[Akimbo]

If the current was strong enough for an interesting drift dive and my computer was nowhere near the red, I would skip the safety stop and inflate the SMB on the surface. If the dive plan would put my computer near red, I wouldn’t be doing a group drift in the first place.

It doesn’t take much current to make deploying an SMB at depth a can of worms, especially when alone. Unless you are exceptionally good, it wouldn’t stand up for easy visibility under those conditions anyway. Is the safety stop really worth the time it takes to deploy an SMB or the potential of losing it and drifting into the sunset?

 

[Splitlip]

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 !

I was going there, so thanks for posting. And in response to Bob's post, I agree. Never heard of a drift dive being aborted if a diver or buddy team gets separated. At least here in PBC. After all, it's a drift dive and the guide/DM is NOT your buddy.

 

[Wookie]

I would, and have, many times. Especially when the "group" has photogs/videographers. I shoot as soon as I find myself separated from the group, and I swim like hell looking down current and don't see them. I do it early to let the captain (I have a special softness for the comfort of dive boat captains) know that I am OK, that I can't find the group, and I should get picked up when he has a minute and he sees us on the surface.

I don't shoot video myself, but as I have entered prime underwater heart attack territory (overweight, white, male, and 50) I tend to stick a lot closer to my buddy than I used to.

 

[Diver0001]

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)?

Shoot it if you get separated and the sooner the better because the crew (I assume you were diving from a boat) will be watching the main SMB and the sooner you pop your blob the better the chances that they see it right away to track you.

R..

 

[The Chairman]

The person with the flag is never lost. If I find myself separated from that person, I shoot the bag immediately. It was interesting to note that on one occasion, I saw the anxiety level immediately decrease among two of the people separated with me. That little tiny link to the surface made them feel better because they knew that the boat knew where they were.

As for diving in large groups... I try to keep it to 4s or 6s at the most.

 

[ScubaToneDog]

The person with the flag is never lost.

Words of wisdom to live by.

 

[TSandM]

I'd shoot a bad as soon as I was sure I was separated. Your chances of reuniting with the boat are much better if the boat knows you are drifting as early as possible. But I have practiced bag shooting until it can be done in much less than 3 minutes -- the hardest thing about shooting a bag where I live is getting the thing out of your pocket!

I think this story shows that SMB deployment is a very useful skill for anyone diving off boats, and should be practiced regularly.

 

[Gombessa]

Sounds like an appropriate question to ask the captain/crew. Not having done many drift dives, I expect that depending on local custom, environment, and accepted procedure, they would have a preferred method/timing of signalling.

If I was in this situation blind, I'd probably decide based on the time to get to the surface. I'm not the fastest bag shooter, and if the drift is 30ft deep, I'd probably be at the surface before having inflated it, and just have it in hand for a surface inflate. If it's a 60-80ft dive, I'd probably shoot as soon as I realized I was separated, on the way up.