Almost went into deco off Islamorada

[redacted]

I can get in this scenario pretty easy, over an aggressive 3 recreational dive series (as I described above). I'm forever warning divers about the dangers of assuming that deco will clear, or NDL will increase just because you ascend and/or multi-level. Yes, on most rec profiles you can multi-level and 'fly the curve' of your NDL up the ascent. However, if you're doing repetitive deep dives, especially square profile (wreck dives & hunting) then you can get into a real sphincter-clencher quite easily and without 'warning'.

I'll dig through my computer and try to find the sequence I'm referring to.

I am not suggesting one should assume deco will always clear during ascent. But it often does on many of the deep recreational dive plans I have examined because it is the faster tissues that are putting you close to deco (or in deco) And those tissues start off-gassing before or around the 30 ft mark.

And just to be clear, I am talking that point in a recreational dive where the NDLs have fallen below 10 minutes. I know there are times early in a subsequent dives and late in any dive where my computer is showing hours of NDL when the dive may, at that point, be regulated by a slower tissue compartment as faster compartments are off-gassing during ascent or as faster compartment have not yet on-gassed enough during a descent to overtake the loading of slower compartment during the initial descent of a subsequent dive.

 

[ianr33]

My meaning was more legitimate concern about being locked out from diving for the next day (DM's rules when you go into deco)

Provided you do what the computer is asking for and clear the deco stops, there will be no evidence you were ever in deco and the DM will be happy.

This is of course totally hypothetical and I would never do such a thing.

 

[DA Aquamaster]

In general I agree if you are close to the NDL and ascend, then the NDL should increase as you get shallower.

Also, if you only have a minute or two of required deco on a computer that accomodates some degree of deco (for example the old pelagic hockey pucks that were not intended for deco but would tolerate deco as long as the stops were less than 30' and the deco was less than 99 minutes), then again, the deco will usually clear on a normal ascent rate before you reach the first required stop depth.

In short, if that's the case, then if you unintentionally enter deco, the response is a normal ascent to the first stop depth (usually 10 feet) do the stop (if still required) and gas permitting do a safety stop.

However it can get strange. For example some computers use a model that penalizes you for rapid ascents, so a rapid ascent (say 60 fpm rather than 30 fpm) could cause the computer to penalize you by adding more deco, or at least not increasing the NDL as you'd normally expect.

And some computers view deco as not much more than punishment and get very conservative once to enter deco and violate an NDL. I don't tthink that approach is very productive. As far as I know there are no longer any computers that just lock you out and stop giving ascent information. Those computers were a really bad idea.

Consequently, while unintentional deco should theoretically never happen, all divers should read the manual and be familiar with how his or her computer treats a deco obligation.

More importantly, if you are deep enough to be incurring deco and are not watching the computer, the odds are good you are also not paying proper attention to your SPG, and/or are not paying enough attention to gas planning to ensure the deeper you go, the greater your reserve to ensure that you'd have the gas to get not only yourself to the surface, but also your buddy in the event he or she had an OOA emergency concurrent during the ascent with or without a deco obligation.

When you start looking at deep recreational diving in the 90-130 ft range that way, the odds are good that you will find yourself doing proper gas planning and more often than not turning the dive on gas rather than based on the NDL.

A decompression obligation has never hurt or killed anyone. It's running out of gas when you have a deco obligation you can't meet that hurts and kills divers.

Edit: Why is it centering all the text in this thread?

 

[DiveNav]

......and you're in the 80-90 ft range once you swim down and out to the corral heads ........ We started a quick but within-the-limits ascent up the slope but my computer stayed on 1 minute for what seemed like 20 minutes. Gradually it grew: 7, 9, 11, 16 minutes until clear......

Hi,
Was this a single dive? Or a dive in a series?

Do you have a more detailed description of the dive profile?

Thanks

Alberto (aka eDiver)

 

[fishb0y]

Also, a dive computer with an alarm function would be a good investment i guess..

Complacency will kill you... that would make this thread more appropriate for this forum.

As the OP said... staying proactive during your dive is better approach. I agree with TS&M completely. All dives are deco dives. Going into deco is not the issue… piss-poor planning seems to be.

 

[Blastman4444]

The decompression chamber techs at St Mary's in West Palm where I went said a lot of their customers are either spear fishing or lobster catching they get carried away not paying any attention to the PSI or computers. At least in your situation everything turned out good and your posting this to inform others what can happen when you get carried away with fishing and not paying any attention to what you should be doing.

 

[openmindOW]

DEAC, thank you for your post.

 

[Deac in the Wake]

Hi,
Was this a single dive? Or a dive in a series?

Do you have a more detailed description of the dive profile?

Thanks

Alberto (aka eDiver)

Definitely a heavy dive rotation. Don't have specific profile with me but we were doing at least 4 dives a day and our SI's weren't as long as they should've been (less than 20 minutes). This particular dive was the fourth of the day so we already had a load and probably should've done more SI and surface swim out to our descent point rather than a drop under the boat and then descending swim out to depth.

 

[xjeslesx]

This thread brings up a common misconception. It is drilled into a divers head from day one that going into deco automatically leads to trouble. Should you avoid going into deco? Absolutely. But if you notice you've slipped a minute into deco, end your dive as you normally would. Your computer may give you a ceiling at a certain depth, this is similar to completing your ndl safety stop.
The point I'm trying to make is that it is safer to slip into deco and ascend slowly than to ascend faster than normal just to beat the ndl.
Just my two cents.

 

[DandyDon]

Read Bob's article about it... NWGratefulDiver.com

Also, a dive computer with an alarm function would be a good investment i guess..

I can set mine to also beep a few minutes before Deco as a warning.

This thread brings up a common misconception. It is drilled into a divers head from day one that going into deco automatically leads to trouble. Should you avoid going into deco? Absolutely. But if you notice you've slipped a minute into deco, end your dive as you normally would. Your computer may give you a ceiling at a certain depth, this is similar to completing your ndl safety stop.
The point I'm trying to make is that it is safer to slip into deco and ascend slowly than to ascend faster than normal just to beat the ndl.
Just my two cents.

I agree, but I think this was also an issue...

My meaning was more legitimate concern about being locked out from diving for the next day (DM's rules when you go into deco)...

And buying the wrong computer...

And FWIW, I'm diving a Cobra 3 so I know we were well within safety margins. I think the only thing more conservative than Suunto's algorithms is just not to dive.

:lol:

​

Definitely a heavy dive rotation. Don't have specific profile with me but we were doing at least 4 dives a day and our SI's weren't as long as they should've been (less than 20 minutes). This particular dive was the fourth of the day so we already had a load and probably should've done more SI and surface swim out to our descent point rather than a drop under the boat and then descending swim out to depth.

Ok that's pushing it. Got a nitrox card...??