Would you really know what was going on if your computer went into Deco...?

[Rick Inman]

I had an unintentional deco dive once during which not all divers had enough air left to finish their last stop, not that they knew exactly how long the stop was supposed to be anyway.
I wasn't able to read my computer properly when it went into deco partly because I was narced, partly because I'd never seen it in deco before, and it had been a while since I looked at the instruction manual. Terrible I know.

Tell us more, tell us more! Where and how did it happen? Inquiring minds want to know...

 

[BradJ]

I came within a minute or two of entering DECO diving in Grand Cayman once. My dive buddy was also using a Vyper and his did enter DECO and locked him out (Err mode) when he didn't do a stop.
So two major diving destinations and two respected dive operators (Bob Soto's in Cayman) resulted in essentially unplanned decompression diving.
My question is are Suuntos too conservative or are these dives going too far.
I consider myself a fairly conservative diver. I always dive less aggressive than the DM, I'm usually more shallow than the rest of the group and I ascend very slowly.

 

[diverbrian]

I take my VyTec and Cobra into Deco intentionally quite a bit, but plan the dives on the Voyager software and my IANTD tables.

A couple of things. The Suunto "ASC" time includes what they call a five minute mandatory safety stop. The three minute SS that we know about, the computer advises you to take but doesn't shorten your dive for the next dive if you don't. The five minute (which is automatic for deco profiles) the computer will still work but take time off your next dive (similar to the fast ascents and short SI situation). I have also seen a four minute "mandatory" safety stop if one of my Suunto computers detects a great deal of repetitive diving.

In addition, the ASC is including deep stops. If it sees off-gassing at all it will count against that time. It may count say one minute off for two or three minutes spent deeper than the ceiling that it says not to violate (normally ten to fifteen ft.). This is why a ten to seven minute deco obligation can "be killed off" in such a non-intutative fashion.

I have to agree with Genesis that the dive profiles that I saw from Cozumel in this thread give me the "heebie-jeebies". The person that killed off the deco did the right thing. They are very lucky that they didn't have a bunch of people in the chamber. That DM should have known better. Reason number 1001 against the "Trust Me" dive!

 

[Spectre]

100 for 30 minutes on 32% is already a deco dive - 5:20 @ 20' according to VPlanner (nominal). Then you did a short SI and a second dive to 80' for 30-40 minutes?!

I don't intend to justify it in any way... but 100 feet on 32% is just about 80 feet EAD. The PADI NDL limit on 80 feet is 30 minutes. Of course, that takes you to the last NDL pressure group that tells you to do a 5 minute safety stop.

 

[diverbrian]

I came within a minute or two of entering DECO diving in Grand Cayman once. My dive buddy was also using a Vyper and his did enter DECO and locked him out (Err mode) when he didn't do a stop.
So two major diving destinations and two respected dive operators (Bob Soto's in Cayman) resulted in essentially unplanned decompression diving.
My question is are Suuntos too conservative or are these dives going too far.
I consider myself a fairly conservative diver. I always dive less aggressive than the DM, I'm usually more shallow than the rest of the group and I ascend very slowly.

I would say that the dives are going a tad too far. But, I saw this in Deerfield Beach as well. It seems to be common in the tropics where the divers are not coming up because they are cold.

In Deerfield, the divers had only themselves to blame as the DM stayed on the boat, LOL. Oh, and the shallow dive that we wanted to do for the second dive was unsuitable due to algae conditions. If we wanted good diving, it had to be moderately deep. And the people there on eighties could stay down seemingly forever.

 

[scubasean]

Aren't you really talking about the classic difference of Table vs. Computer?

My philosophy is that every dive is a decompression dive. If I trust my computer to keep my un-bent on some dives( what is normally called a no-deco dive) why not on all?

Now I do understand that each algorithym, whether in a table or in a computer, has quirks. A person just has to decide what quirks they are most comfortable with?

Actually it isn't the same as the "classic" difference between tables and computer for at least one reason I see, and it is a good one...

If I recall correctly, in the manual that came with the computer my computer manufacturer says that the computer is NOT for intentional decompression (read that as mandatory deco, since I agree with your point that all diving is deco diving.) diving.

 

[J1M1]

Would you really know what to do...?

Have you ever done it...?

I wonder if it might be a good idea to intentionally run it over a couple of minutes in the red in very calm and controlled conditions then work off the Deco obligation plus 3-5 minute Safety Stop as well - all as a practice & learning session?

I've asked a few, and the most common response is: "If it beeps, I'll know I have a problem to ask about." :klo:

don

Sure. Longest deco i've been in was a little over an hour. my computer worked flawlessly where most computers would stop giving deco info. Use the tables and bt for backup always. I do not agree with placing yourself into required deco before you have the training to deal with the obligation IN ANY SITUATION. a person could get seriously hurt. J.D.

 

[DandyDon]

Lots of interesting comments, folks. Thanks!!

Getting proper training is a wonderful idea, unless you live on the high desert of West Texas. Not so readily available as it may be other places.

Brad's experiences in Cozumel and a few others mentioned here point out many of the problems I'm wondering about...

(1) I don't know that I've ever seen a DM wear a computer in the Caribbean, and I've been around a bit.

(2) I have seen Caribbean DMs dive what I thought were excessive profiles, and customer divers without computers follow them in trust. DMs on my Devils Throat dive were all using 32% Nitrox to avoid DCS, but then they went below the 1.6 bottom! Just because a DM does it, especially outside of the U.S., doesn't make it safe.

(3) When a Computer goes into deco, the wearer doesn't know what it means for sure, and/or what to do about it.

don

 

[truva]

I have seen the Dive Guides in various places run profiles that expect each diver to watch his on butt, they hardly ever do. On the other hand we constantly “ride” the deco limits on our old Eons’. If we are diving a wall we usually take care of the obligation by just going up 10 feet or so till it dings again and keep doing that. I have no problem busting the deco limits on the suunto computers they are a bit on the conservative side just do what it says and maybe a more if you are going on days of diving. I use the things to maximize my dive time and that’s what they do.

Anyone that dives in “trust me” mode is just as stupid has someone that spends 400 to 800 dollars on a computer and then doesn’t RTFM.

Truva

 

[ArcticDiver]

Actually it isn't the same as the "classic" difference between tables and computer for at least one reason I see, and it is a good one...

If I recall correctly, in the manual that came with the computer my computer manufacturer says that the computer is NOT for intentional decompression (read that as mandatory deco, since I agree with your point that all diving is deco diving.) diving.

Guess I didn't mean "classic" in that sense. More in the sense that it is an ongoing, seems like forever argument/discussion.

It is interesting what the various manuals say. For example the VPPlanner web site says that divers use their tables at the diver's risk. That the tables are experimental and not guaranteed to do anything but occupy space. Yet some divers swear by them and they are obviously marketed to plan safe dives.

My computer manual says the machine isn't for intentional decompression diving and then proceeds to give procedures for doing it.

Anyway, we stray. My purpose was only to point out the logical inconsistency of relying on a computer for some dives but not others when all are hazardous to your health. If a diver doesn't like computers and wants to do it all manually; fine. If another wants to use a computer, fine. It really doesn't matter as long as the user reads and follows all instructions.