Brief Unplanned Surfacings

[Marek K]

I haven't found anything here on this subject, but it's something that happens periodically.

Bouncing is bad. But for whatever reason (carelessness, current, nav error), a buddy team can get disoriented as to where the boat is. What I've often seen, at least in shallow water (20-30 ft), is that one member (usually the most-experienced one -- I've seen divemasters or instructors do this several times) surfaces briefly, spots the boat and takes a bearing on it, then descends again to continue the dive in that direction.

I'm not sure I'm real comfortable with this procedure, for a couple reasons... First, even assuming proper ascent rate, how does this affect decompression/recompression? My computer, for one, treats brief surfacings (<10 min) as a single dive, but can I rely on that being safe? Second, it obviously splits up the buddy team.

So, should both/all members of the team surface together to shoot a bearing to the boat? Then what... Continue the planned dive, or at that point abort the dive and just do a shallow swim (15 ft?) back to the boat?

Related question... PADI, anyway, standard procedure for when you lose track of your buddy has always been to do a brief search (not more than 30 sec), then surface and link up there. But I don't remember any doctrine about what to do then. Would there be any problem with descending again after that to continue the dive?

--Marek

 

[DandyDon]

I like your questions! 2 that should have been taught, but I don't believe that Padi does.

I don't like surface swims, especially in waves, so if I cannot find the boat without surfacing, I'll do my slow ascents, deep & shallow stops (Paid doesn't teach deep stops yet, I don't think), make sure my computer is happily in the Green, then surface to shoot a bearing on the boat. This is safer than risking going the wrong way and getting futher out. Then, I will submerge, but only to 5 or 10 feet for the swim. I don't see this as a bounce, not at that depth. You'll notice that your computer will give you a 9 hour limit at that point.

Should both surface together? Danged right! Doesn't play that way often enough, but should, and both shoudl shoot the bearing. Except, the last time I did that with a newbie, he didn't allow for slight current, and we got seperated - then didn't surface for 5 minutes, although I was atop watching for 4 minutes. Thought I'd lost one!

But, if I get down to 500#, I'll surface, fill my BC, turn on my back, and paddle in. I'll use the 500# if needed (don't want to drown just safing your last 500# for the capt to see), but save it for urgencies! And if I can't get to the boat easily, I'll whistle and wave for help. My job is to be reasonable about safety, even if I have to sacrifice ego, and his job is to save me as needed.

Your related question is stickier. If it's a dive to 20 feet, I'd go back. To 60 feet, not sure. To 100 feet, nope. I'll look forward to other answers on this one! Thanks!

 

[String]

Saw tooth profiles are to be avoided if possible and its worth remembering the greatest pressure change is going to be from 10m to the surface in terms of gas expansion/bubbles so popping from 10m to surface is "worse" than popping from 20m to 10m.

That said as long as it isnt done huge numbers of times its not THAT bad.

FWIW some research published a few months ago found a greater risk of DCS in dives that were in theory no stop but were skirting the NDLs than were present in saw tooth style bounces.

 

[ScubaCollin]

Greatest pressure change is in the first atmosphere, so youre more likely to get hurt within the first 30 feet. So yea what that person is doing is wrong(especially for a divemaster).

Lose your buddy? Make some noise with your knife, hit it against your tank. Doesnt work? Look around 360 degrees for bubbles. If this doesnt work. For god sake, take 3 minutes out of your dive for a safety stop.

 

[ScubaDadMiami]

It all depends.

If you are doing a relatively shallow dive without decompression obligations, surfacing briefly for a short time (one minute or so) and then descending should not be a problem.

Remember that it takes a few minutes for the drop in ambient pressure to start significant bubbling. Navy protocols and commercial entities sometimes have to have divers ascend to the surface for logistical reasons (battle zone, etc.). In those cases, they race the diver to the recompression chamber on site. So long as the diver gets there within five minutes, this is also not a problem.

Deeper/longer dives require adjustments for deco related issues if you are getting near the limit. If I were in a deco situation, I would shoot a lift bag, hoping that the boat sees me even if I can't see the boat. I would carry out deco. After surfacing, I would hope that the boat comes to me if this is a heavy duty dive. If the boat is at anchor and this is not the type of dive where they will come get me, then, after surfacing, I would take a heading and follow it on or very near the surface until arriving at the boat.

Regarding how deep to go after ascending, you want to make sure that, if you are in an area frequented by marine traffic, you are on the surface with some type of visible marker. If you elect to descend, you want to descend deep enough to avoid getting run over while not going so deep that you are crushing bubbles and then allowing them to move into regions of the body where they can do damage once you surface and they expand.

Like I said, it all depends.

 

[DandyDon]

Remember that it takes a few minutes for the drop in ambient pressure to start significant bubbling. Navy protocols and commercial entities sometimes have to have divers ascend to the surface for logistical reasons (battle zone, etc.). In those cases, they race the diver to the recompression chamber on site. So long as the diver gets there within five minutes, this is also not a problem.

The Deco obligation would be significanlty increased after the first minute, though, would it not?

 

[scubapro50]

My wife hates open water accents .... but if you lost the boats' line it's better than swimming in the wrong direction. This is why I always wear a snorkel .... rolling on my back forget it .... if you come up in rough seas or in a current then the backstoke doesn't cut it ..... if possible get your bearings, put your head down in the water and swim toward the boat. You get a lot more power using your legs and wearing a snorkel than sunbathing on your back.

 

[Iruka]

Just addressing the question of "should both people surface?".....here in Guam, where you generally have very good visibility, I don't feel that's necessary, as long as both people (surface & submerged) keep an eye on each other. As this surfacing to find the boat is normally done near the END of the dive, it will usually occur in shallow (10~20') water, so keeping everyone in sight is pretty easy. Also, especially when you have people in 5mm wetsuits, with tanks only 1/4 to 1/2 full, they're lighter than when they started, and if they're not weighted correctly, they will find it difficult/impossible to submerge again at that point. I always tell my divers, "if I surface, just stay where you are, unless I signal otherwise," and if anyone is underweighted & floats to the surface near the end of the dive, if they can't easily submerge, just continue on the surface, above the rest of the group...DON'T just swim off on your own! If I have a diver who's a little light late in the dive, I usually have an extra wt. or 2 to "loan" them, but at the end of the dive, sometimes there's no way to sink them again.
As ScubaDadMiami said, "it all depends." Sometimes (usually after typhoons) visibility in the top 5m/15' will be TERRIBLE....and I can't reliably see my divers hanging on the line doing their safety stop while I'm at the ladder helping them remove fins or whatever. In a case like that, I bring everybody up to the surface together, inflate BCDs, and then help them at the ladder one at a time. I'd hate for some (unseen) diver to sink off into the abyss while I'm on the surface helping someone else!

 

[Xanthro]

I'm trying to understand how a slow ascent very short surface interval then a shallow descent is going to harm you.

As long as your last 20 feet or so is down very slowly, I can't see from a physical point of view how your are going to endanger yourself. Bubbles won't have nearly enough time to form in tissue, and if they somehow did, you'd have the same problem even if the dive was finished.

I think much of the "don't bounce" is because too many people don't take the last 10 feet seriously, when in fact, that's when most vein off-gassing in the lungs occurs. The fewer times you do the last 10 feet incorrectly, the better. If you do it right, you aren't doing it incorrectly.

Xanthro

 

[Marek K]

OK, we've got two different but related issues... the physiological decompression/recompression issue, and the physical-safety buddy separation issue.

So far I see that, like a lot of procedures, it may all depend.

First of all, my question had to do with no-deco diving, and depths of maybe up to 60 ft/18m. Any deeper than that, and I think the factors might be different... I'd say in that case, buddies surface together if looking for the boat, and once they're on the surface that may be the end of the dive. But it'd be interesting to hear those views, too.

Shallower, and whether just one person pops up to look for the boat would depend on a lot of factors... visibility, depth, danger from boats on the surface, how far into the dive you are, how much air you've used, experience of the team (buoyancy control), etc. Good things to consider.

As far as the "lost buddy" drill, though, I think the SOP of "30 seconds search, then surface to link up" makes a lot of sense. Of course you need to search for a short time -- signaling, looking for bubbles, etc. But if you can't find your buddy within 30 seconds, something's terribly wrong... you've certainly screwed up as a buddy team, and nothing's going to un-do that; maybe someone's panicked and gone to the surface, or something... Any longer and the risks increase.

In any case, you can't forget about a proper ascent -- though if you're missing your buddy, waiting the extra three minutes for a safety stop may be tough to do.

Once on the surface, then, what I'm hearing is that another factor as to whether you abort the dive or not would be how long you spend there. What's the thinking there? A minute is all right? Three? Five? Should computers be able to safely take that into account if you descend again to depth?

In all of this, it's easy to forget that the greatest rate of percent pressure change is near the surface.

--Marek