Would You Use a DSMB in this Scenario?

[xyrandomyx]

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?

So far you're the only person to give a dissenting opinion. Can you perhaps give a clearer idea of what 'strong enough for an interesting drift dive' is? I'm wondering if the reason for the difference in opinion is that you like your current a little stronger than the others that replied.

---------- Post added December 8th, 2012 at 12:25 PM ----------

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.

I'm completely sold on the idea that DSMB deployment is a valuable skill that should be practiced regularly. I'd also like to know, though, if there are situations when shooting an SMB from depth seems like a good idea but actually isn't. Part of knowing how to use a tool is knowing when it's the right one for the job, no?

---------- Post added December 8th, 2012 at 12:28 PM ----------

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.

Locally, there's virtually no current (a mild surface current on occasion), so I have even less experience with drift diving than diving in general. How are drift dives from a boat (didn't even think of the existence of shore drift dives in my original post) typically conducted where you are? In entirely indepedent buddy pairs? Does each pair tow a float/ flag/ SMB or does the captain just follow bubbles? Assuming there are several people on the boat, I presume everyone would have to at least start out in roughly the same place in order for the captain to keep track of all the groups?

 

[Tigerman]

All buddy pairs, independent on where you are diving, are by default independent. You got your certification under the premise that you should be able to conduct dives with no more support than a buddy, in conditions similar to or better than the ones in wich you received your training.

Most dive ops will not start panicking if they are missing A PAIR of divers out of a group, they will however in most cases start freaking out if they are missing only one diver on its own, especially if its not a diver they know have solo diving experience/certification/equipment..
They will of course start worrying about a pair of divers too if they cant see an smb while time limits are overdue and so on though.

 

[xyrandomyx]

All buddy pairs, independent on where you are diving, are by default independent. You got your certification under the premise that you should be able to conduct dives with no more support than a buddy, in conditions similar to or better than the ones in wich you received your training.

Most dive ops will not start panicking if they are missing A PAIR of divers out of a group, they will however in most cases start freaking out if they are missing only one diver on its own, especially if its not a diver they know have solo diving experience/certification/equipment..
They will of course start worrying about a pair of divers too if they cant see an smb while time limits are overdue and so on though.

Yes, but I don't see how that precludes my buddy and I making dive plans which call for sticking with a group (of buddy pairs) and ending the dive if that group should be separated. If it's done for convenience or out of personal preference, rather than the expectation that someone else in that group will bail you out in a tight spot, I don't see the problem.

 

[o2dependant]

It would depend on whether I drifted away from them or if they drifted away from me. Usually It would be standard to surface after 1 minute seperation to re-group at the surface. If I was behind the group this would be my course of action. If a safety stop was required I would deploy the SMB during my safety stop to mark my position to anyone who could see it.

If I was ahead of the group or did not know where I was in relation to the group, I would deploy the SMB before surfacing at depth if thats where I was to signal the crew that I was ahead of the pack ASAP, and making my way up.

 

[MXGratefulDiver]

I'm completely sold on the idea that DSMB deployment is a valuable skill that should be practiced regularly. I'd also like to know, though, if there are situations when shooting an SMB from depth seems like a good idea but actually isn't. Part of knowing how to use a tool is knowing when it's the right one for the job, no?

One such condition that I've experienced is when there is a surface current, but no current at depth. I did this once on a training dive, where we were required to shoot a bag at our first deco stop ... 70 fsw in this case. The surface current was quite a bit stronger than the current where we were at, and the bag literally pulled us in a direction we didn't want to go. Unfortunately, we had about 20 minutes of required deco. We'd have been much better off doing the deco first, then shooting the bag at a much shallower depth ... if at all.

Of course, the caveat is that you would have to know, or anticipate, that the current at the surface was much different than that which you were experiencing at depth ...

... Bob (Grateful Diver)

 

[xyrandomyx]

One such condition that I've experienced is when there is a surface current, but no current at depth. I did this once on a training dive, where we were required to shoot a bag at our first deco stop ... 70 fsw in this case. The surface current was quite a bit stronger than the current where we were at, and the bag literally pulled us in a direction we didn't want to go. Unfortunately, we had about 20 minutes of required deco. We'd have been much better off doing the deco first, then shooting the bag at a much shallower depth ... if at all.

Of course, the caveat is that you would have to know, or anticipate, that the current at the surface was much different than that which you were experiencing at depth ...

... Bob (Grateful Diver)

OK, that's useful to know. We do sometimes get a surface current here (no currents at depth). It's generally fairly mild (maybe 1 kt at most?). I've never heard of the current coming up unexpectedly, so it should be possible to tell if there's a current at the surface when you hop in at the start of the dive. I've heard of (in other locations, not locally) the surface current running in the opposite direction to the current at the bottom. I'm guessing that might be another situation in which shooting a DSMB may not be the best idea?

 

[MXGratefulDiver]

I've heard of (in other locations, not locally) the surface current running in the opposite direction to the current at the bottom. I'm guessing that might be another situation in which shooting a DSMB may not be the best idea?

I know of a local dive site where that happens with some regularity ...

... Bob (Grateful Diver)

 

[idive2]

I have not seen currents at depth running in a opposite direction than the surface current but I have seen the
currents at shallower depths running at lesser or greater strength than current at depth. You will be told at times
to follow the line up that the guide is towing as a way to stay near the flag. This can be very problematic with
a different current at say thirty feet than at the bottom. I have more than once attempted to use the guides tow flag
line as a reference for my ascent only to see them hook off to something on the bottom for what appeared to be a reason
of their own. You need to have a buddy of your own and be prepared to make your own safe ascent when required.
My comments refer to a drift dive in which the guide is towing a flag and that is the only flag being towed for the group.

 

[TSandM]

If it is a live boat, I cannot think of a circumstance where shooting a bag if you are separated from the group would be bad. Even if there is surface current you don't expect, you are still marking yourself for the boat. Any other group towing a float or flag is being pulled by that current, too.

If it is an anchored boat and you have lost the anchor, that is a little different. If there is a risk of surface current, and you can see the bottom, you might be better off getting shallower before shooting a bag, as long as you are sure you are not drifting. If you can't follow the bottom, I still think you are better off shooting a bag early, so that the boat knows they have a buddy pair moving away, and what direction they are moving. They may not be able to come get you until they've retrieved the divers who DID find the anchor, but at least they'll have a clue where to look.

 

[dumpsterDiver]

As others have said, it is really easier to deploy from depth, because you only have to put a puff of air into it.

Deploying a marker should NOT take any time at all. You should be coming up at your normal speed while at the same time deploying the bag. So even though it might take you 2 minutes to deploy, this time is required for the ascent anyway. It does NOT take extra time to deploy it.

However, the task loading .. ie., concentrating on the bag rigging underwater CAN EASILY cause you to lose track of your depth and ascent rate. So you do need to practice, but again, if you screw up the ascent rate a little at 80 feet, it is much easier to recover from it, than if you do it at 20 feet. It DEFINITELY TAKES PRACTICE!.

If you are good at the deployment, you start up from say 100 feet and remove the bag and reel or spool and get it all assembled... "In a minute or so you are at 60 feet and the bag should be ready to blow. Stop for 5-10 seconds, send the bag up and you should have a nice leisurely ascent. There is now ZERO rush to ascend and let the boat know you are "lost". the bag sends that message immediately for you.

Deploying from depth, puts the marker on the surface much sooner and this is a big safety advantage in that the boat operator is more likely to immediately notice its' arrival on surface if it is in reasonable close proximity to the marker the DM is pulling (the one the boat is following.)

If you wait until you reach the surface, you are deploying maybe 5 minutes later... this can make the difference between being seen and not.

As for the issue of strong surface currents and slow current at depth, not a huge problem if you have a little lead balast on the weight belt, and if it gets really bad and is hauling you to the surface, just let it go. It would be pretty unusual .. I send up SMB's from 180 feet and sometimes it does pull pretty hard and you are sailing through the water and it tends to pull you up some. In these cases it is nice to have 300 feet on the reel, so the pulling is more down current than up.