Descended quickly to 35 feet. Can you briefly go to surface then resume planned dive?

[boulderjohn]

Didn't you do a Buddy check?

IMO, the standard buddy checks have a deficiency that makes it too easy to make a mistake like this. When you suit up, in most cases the very last thing that you put on are whatever you put on your wrists, which often includes a computer. It is perhaps the easiest thing to miss. Then you do your buddy check. At what point do you check to see if you put those last items on your wrist? In almost every different buddy check system I have seen, there is nothing specific enough to point to those items.

Let's take the PADI B-W-R-A-F system. On which of those 5 items does it occur to you to make sure you put your computer on your wrist?

About 7-8 years ago I read on SB of a related incident. A man was preparing to do a dive on EANx 32, and at the last minute he changed his mind and switched over to an air tank. He forgot to change his computer. He took it near the EANx 32 limit and got bent. Based on that incident, I wrote a suggestion to PADI that they change the BWRAF system to add and I for instruments. That I would remind you to check to be sure you had all your dive measuring devices on you and properly set. The response was enthusiastic. They told me everyone thought it was a great idea, they were working on a new acronym, and it would start being implemented when the next manuals came out.

It obviously never happened.

So I decided to implement it myself. I teach my students to use BWRAIF, the mnemonic we use is Bruce Willis Ruins Another Independent Film.

 

[katiegw]

I'm interested in the responses to this thread, because this same situation happened to me today, but for a different reason. My buddy and I were diving an inland lake here and MI, and attempted to begin our dive at the deepest part of the lake, where there was a 50 foot deep area. However, at about 35 ft and below, we realized that viz at depth was zero. We're talking blackout conditions. So we both surfaced (with a nice calm, slow ascent), and then surface swam a long way to another part of the lake to resume our dive in the shallows at about 15-20 ft. The viz still sucked (maybe 5 ft), so we killed the dive after about 20 min. In this case, NDLs were not an issue, but it made me wonder if there were any other potential consequences from this dive profile.


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[spectrum]

Pete - are you assuming that the diver also has a timing device along with the SPG? For most divers, the computer is depth gauge, SPG, and timer.

Going in without a computer often means going in "deaf, dumb, and blind"

As I heard someone say about PCs in the workplace "The best thing about everyone having a computer is that we can make twice as many mistakes in half the time!"

In the case I suggested which applies to most single dive days there is no need for a time piece. If the specified depth, supply and consumption predetermine the dive to be non deco so dive till you hit turn pressure and come up easy.

---------- Post added August 9th, 2015 at 09:22 PM ----------

I'm interested in the responses to this thread, because this same situation happened to me today, but for a different reason. My buddy and I were diving an inland lake here and MI, and attempted to begin our dive at the deepest part of the lake, where there was a 50 foot deep area. However, at about 35 ft and below, we realized that viz at depth was zero. We're talking blackout conditions. So we both surfaced (with a nice calm, slow ascent), and then surface swam a long way to another part of the lake to resume our dive in the shallows at about 15-20 ft. The viz still sucked (maybe 5 ft), so we killed the dive after about 20 min. In this case, NDLs were not an issue, but it made me wonder if there were any other potential consequences from this dive profile.


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As described with one extra gentle ascent from 35 feet latter returning to 20 you are fine. Many such ascents done aggressively could leave you feeling like crap.

An aggressive surface swim could be a slight issue but after only a brief visit to 35 feet and a gentle ascent even that is a very remote concern.

 

[TSandM]

If you think about it, the proscription against surfacing and redescending is mostly about nitrogen behavior. If you have just jumped off the boat and gone rapidly to 35 feet, you have absorbed very, very little nitrogen above what you started with. In fact, you can spend almost an infinite amount of time at 35 feet, and still go directly to the surface (although in such a case, redescending might not be wise). So, from a decompression standpoint, a descent to 35 feet and an immediate return to the surface is a mere blip in the nitrogen absorption graph. (This is, of course, assuming it isn't your fourth dive of the day )

There may be other reasons why an ascent and redescent might not be wise -- for example, if you are drift diving off Cozumel, and the entire group has continued with the current, and you are now so far behind you can't catch up, or if you were supposed to do a "hot drop" where the captain set you in the water a calculated distance upcurrent from a wreck, and you will now miss it.

As spectrum pointed out, there are some dives you can quite safely do without a computer, and those are the ones where the important parameters are set by the topography. For example, we have a dive site here in Seattle where you can only reach 40 feet at the very, very far boundary of the park, and most people can't get there on gas. For that dive, using half your gas going out and half coming back is really all you need to know. An SPG is enough for that dive.

My husband likes to say, when he is teaching OW, that there are two acceptable answers to most all the course questions: "It depends," and "Knowledge Review 1 Q 1" (which is the Boyle's law matrix). Most diving questions can be answered by analyzing the question in view of what you were taught as basic concepts, and example is my analysis of this question in the first paragraph. But the other part is the "it depends", which is the paragraph above this one.

 

[jonhall]

What are the consequences of taking a trip to the surface near the beginning of a dive?

Scenario: Descend to 35 feet. Discover don't have dive computer on arm. Continue or get the computer?

What if the reason to ascend was something else?

Thanks!

My scenario was dropping my camera after entering the water. I forgot to attach the strap to my wrist and when I let go of the camera, it went. I just reacted and swam down 65 feet to pick it up. Swam back up to 12 feet and joined everyone else just before dive master led dive. According to dive profile and computer signal, I ascended too quickly for about 20 seconds. It was on the first of a 2 tank dive and I went to a depth of 98'. Dive was 52 minutes. Didn't suffer any problems on either dive. Should I have been more careful during that first ascent so close to the beginning of the dive?

 

[The Chairman]

If I was doing a couple of shallow dives here in the Keys, I wouldn't sweat the PDC if I didn't rely on it as an SPG. If I was doing a series of dives over a few days, I would go back to get my PDC. Relying on your buddy's PDC is no good in that your PDC won't have the residual nitrogen from this dive. I have found that putting my PDC on the left D ring of my BC is a great way to never leave it behind. But since my PDC is wireless Air Integrated, I just don't take the chance of diving without it. I usually wear two if I'm going deep. It only makes sense, in case one dies.

 

[Hawkwood]

... I have found that putting my PDC on the left D ring of my BC is a great way to never leave it behind...

That's were I put my "backup" computer (i.e. my wife's computer when she's not diving). It goes on there and usually never gets looked at...until the couple of times I've forgotten mine.

 

[Frosty]

if my computer wasn't with me Im freediving anyways so no worries.

 

[Nasser]

IMO, the standard buddy checks have a deficiency that makes it too easy to make a mistake like this. When you suit up, in most cases the very last thing that you put on are whatever you put on your wrists, which often includes a computer.
Let's take the PADI B-W-R-A-F system. On which of those 5 items does it occur to you to make sure you put your computer on your wrist?

I wrote a suggestion to PADI that they change the BWRAF system to add and I for instruments. That I would remind you to check to be sure you had all your dive measuring devices on you and properly set. The response was enthusiastic. They told me everyone thought it was a great idea, they were working on a new acronym, and it would start being implemented when the next manuals came out.

So I decided to implement it myself. I teach my students to use BWRAIF, the mnemonic we use is Bruce Willis Ruins Another Independent Film.

Yes, I did the same thing myself. From BAR (Buoyancy Air Releases) to BARC - the C being Computer. It wasn't only to remember to put it on, but also to switch it on, check the battery charge, gas information inputed, and make sure none where accidentally switched on or off that weren't needed for the dive... and maybe a quick run through of the NDL planner.

I agree that updating the acronym that one uses is a good idea and should be a reflection of your overall current configuration. It does, however, still ultimately point to the same overall concept.... which is to employ the Buddy check as a method of reviewing your gear (or buddy's gear and vice versa) to confirm all is well, and to try and pre-empt any possible equipment issues prior to getting into the water.

 

[archer1960]

...

Let's take the PADI B-W-R-A-F system. On which of those 5 items does it occur to you to make sure you put your computer on your wrist?

About 7-8 years ago I read on SB of a related incident. A man was preparing to do a dive on EANx 32, and at the last minute he changed his mind and switched over to an air tank. He forgot to change his computer. He took it near the EANx 32 limit and got bent. Based on that incident, I wrote a suggestion to PADI that they change the BWRAF system to add and I for instruments. That I would remind you to check to be sure you had all your dive measuring devices on you and properly set. The response was enthusiastic. They told me everyone thought it was a great idea, they were working on a new acronym, and it would start being implemented when the next manuals came out.

It obviously never happened.

So I decided to implement it myself. I teach my students to use BWRAIF, the mnemonic we use is Bruce Willis Ruins Another Independent Film.

I like it! Only like the mnemonic "Because We Really Ain't Indigenous Fish"

---------- Post added August 10th, 2015 at 07:51 AM ----------

My scenario was dropping my camera after entering the water. I forgot to attach the strap to my wrist and when I let go of the camera, it went. I just reacted and swam down 65 feet to pick it up. Swam back up to 12 feet and joined everyone else just before dive master led dive. According to dive profile and computer signal, I ascended too quickly for about 20 seconds. It was on the first of a 2 tank dive and I went to a depth of 98'. Dive was 52 minutes. Didn't suffer any problems on either dive. Should I have been more careful during that first ascent so close to the beginning of the dive?

Considering how quick your bounce to 65 was (meaning little time for on-gassing), and the fact that you went back up to what was basically "safety stop" depth, it's difficult to see how that would have much chance of trouble.