As a rec diver, what to do if I breach my computer's NDL???

[GrumpyOldGuy]

I don't see a big difference between hitting NDL and going into light deco on a computer: The computer may have a very definite, sharp line between the conditions, but your bodies limit that day could be either side of the line and so anytime you plan on even coming close, you should be prepared. Be prepared I mean having enough gas (primary and redundant) to do the computer required stops PLUS a normal safety stop (I am old, fat and biased towards be cautious). On the other hand, if you are not prepared to do a deco stop, then you should not be diving to NDL.

 

[navi_jen]

This is a great thread. Too bad it's in the advanced folder, this is a good thread to be read by newbies too.

I ran into this exact situation on my second (or third??) dive trip. I was diving on a rented computer, and was diving very aggressively...and didn't understand that my computer was telling me to get the h%ck up into shallower water. So as a reward, I had a 6 hour ride in GC's lovely gas tank. I am ridiculously conservative now, own two computers, but have always worried what a deco stop (on my Sunnto) looks like in real time. You can read the manual all you want, but at least for me, it doesn't stick until I see it live (trust me, this foilable isn't just in diving, either).

The 'double computer fake deco' is an excellent idea. It's on my list for my next trip. Also, an excellent reason why a computer should be one of your first purchases!

Too bad we can't move this to the newbie section...it would be a great one for a lot of us 'pretty fish' divers to read.

 

[Rhone Man]

When I was diving in Philippines once, my Suunto gave a bleep as I tripped into deco on a recreational dive and the dive master looked at me quizzically (he was worried I was low on gas). I gave him the extended pinkie signal to let him know I was technically in deco and he signalled OK and we carried on. The deco cleared before the safety stop.

Back on the boat he asked me: "What was that hand signal you gave me down there?"

View attachment 175064



Either of these work...

 

[Tigerman]

Brilliant. If you get a signal you dont understand and just go "ok" that solves the "issue"

 

[lowviz]

...//... "What was that hand signal you gave me down there?"

Answer: Easiest signal to remember! It means that I'm just a little F'd up at the moment, it will clear...

 

[DevonDiver]

Brilliant. If you get a signal you dont understand and just go "ok" that solves the "issue"

 

[Centrals]

Either of these work...

I understand both hand signals but not sure if everyone does especially on deco.

 

[lowviz]

Been there once.

Did: YOU, WATCH ME, tap dive computer, Signal CEILING above my head, then YOU, STOP (both hands). It worked.

 

[dumpsterDiver]

]One of the reasons why recreational computers can't be used for staged decompression diving is that they don't behave like real deco algorithms. [/B] I have read stories of dive computers racking up ridiculous amounts of deco when the diver didn't immediately march to the stop depth and stay there. Some of the computers do not give you any credit for offgassing below the mandatory (shallow) stop depth. Others will do as described, and clear as you ascend. Unless you are quite knowledgeable about the behavior of your own computer, it's unwise to dawdle when you are showing a ceiling. People without decompression training won't know if the 60 minutes of mandatory deco their computer is now showing is reasonable, or whether it's the product of a device that was never designed to do what you are doing with it.

My husband did a dive at the Catalina Dive Park years ago, using his Suunto computer in computer mode. It was the second dive of the day. There were six of us diving together. Of the six, only Peter incurred any deco (even though we had all dived very close together, and Peter and his buddy did EXACTLY the same profile). By the time we got to the stop depth, his computer was showing TWENTY MINUTES of decompression, and nobody else had any. Luckily, he had the gas to sit and wait it out, and he did, because he wanted to use the gauge for the next dive and so he had to make it happy. He knew darned well, as did we all, that he didn't really owe a twenty minute deco obligation. But if you don't have the training and this is what your computer is saying to you, and you realize you don't have the gas to do the time, you are in a world of hurt.

I agree that some computers like Suunto don't seem to be practical for doing deco diving, however there are other computers that do seem to be able to do it pretty well... Or I wouldn't be here. I've followed computers for deco dives up to maybe 30 minutes or so, that is the max I will ever probably do with a single primary tank. I have had reasonably good luck with Oceanic computers over the years and we used skinny dipers for many years too, although those computers were bad because they never told you your deco time- they just told you where to stop and when your stop was over, but never how long it was.

I'm not sure exactly how you distinguish recreational computers from others?

 

[Dirty-Dog]

I am not familiar Stinger, but if it has the same algorithm as the Cobra and others that are not designated DS (deep Stop), then you piled up more required deco time during the 5 minutes you were at 40 feet.

I did indeed. That's why I owed 10 minutes at 15. But again, I knew what was happening, what to do about it, and that I had more than enough gas to deal with it. Even without a card, going into light deco isn't the end of the world. And, despite what another poster has recommended, it's not something that requires punishment. Although obviously, if I'd blown off the deco obligation, either through lack of gas or lack of understanding, then [video=youtube;kNwbjcuQUv8]http://www.youtube.com/watch?v=kNwbjcuQUv8[/video] would have been appropriate.

Been there once.

Did: YOU, WATCH ME, tap dive computer, Signal CEILING above my head, then YOU, STOP (both hands). It worked.

It's amazing how well we can make ourselves understood, even if we don't have a specific signal.