"I'm so conservative..."

[Dogbowl]

FWIW, I sold that computer after that one trip.

Hahaha, I was gonna ask, but you beat me to it, so did you toss that computer in the garbage...

Was it a Suunto?

 

[scubadada]

@Hoag

How did you end up with an unplanned deco obligation of 5-10 minutes? That's a bit more than just a trivial overstay at depth.

 

[Hoag]

Hahaha, I was gonna ask, but you beat me to it, so did you toss that computer in the garbage...

Was it a Suunto?

Yes it was.

 

[Hoag]

@Hoag

How did you end up with an unplanned deco obligation of 5-10 minutes? That's a bit more than just a trivial overstay at depth.

I prefaced my comment with "IIRC". I could very easily be remembering the specific time wrong. It was a long time ago.

 

[dmaziuk]

Hahaha, I was gonna ask, but you beat me to it, so did you toss that computer in the garbage...

So now if you dive the exact same sequence, end up with exact same tissue loading, and your new computer says you are not yet in deco, and that makes you OK, right? I mean, it's not the actual gas in your tissues, it's the numbers on computer screen that matter, correct?

 

[Hoag]

So now if you dive the exact same sequence, end up with exact same tissue loading, and your new computer says you are not yet in deco, and that makes you OK, right? I mean, it's not the actual gas in your tissues, it's the numbers on computer screen that matter, correct?

No, of course it is the actual tissue loading that is important. However, this particular computer was so dramatically more conservative that it was virtually unusable if I was planning on doing 4 dives per day. All the computer will do is display what it calculates as based on the algorithms that it has been programmed with. In this case, I was willing to accept the risk associated with a computer with a slightly more liberal algorithm.

 

[boulderjohn]

. Before the dive, did you and your buddy explicitly agree to dive within rec limits, i.e. no deco, and/or was it a boat rule? If the answer to either is yes, then he purposefully violated one or both of the agreements. If the answer is no, he may of simply been diving his usual "conservatve" profile. The wisdom of doing so has already been extensively discussed.

The dive was what is called a "double dip"--two dives on the ame wreck. There were some people doing one deco dive instead, so people were pretty much on their own for what they were doing. I assumed from the fact that he had a single tank, no redundant gas, and no deco gas that he was doing an NDL dive. A trained deco diver would not do a deco dive with that equipment.

 

[scubadada]

The dive was what is called a "double dip"--two dives on the ame wreck. There were some people doing one deco dive instead, so people were pretty much on their own for what they were doing. I assumed from the fact that he had a single tank, no redundant gas, and no deco gas that he was doing an NDL dive. A trained deco diver would not do a deco dive with that equipment.

On all double dips I have done, the options were explicitly 2 recreational dives (no deco) or 1 technical dive.

 

[Lorenzoid]

Seems there's a practical lesson to be learned here: Don't assume the dive plan is to remain strictly within NDLs, but rather explicitly go over that with your buddy. Even if the boat's briefing indicates that it's "no deco" for you, make sure your buddy understands what that means. You could go a step further and agree to use hand signals to advise your buddy of how much no-deco time you have left. I do this by pointing to my computer with an index finger and tracing a circle (like the hand of a clock), and then signing a number. You could agree to let each other know when you get within, say, three minutes of your NDL. First one to approach NDL controls when both buddies begin ascending.

And of course if you happen to have the same computer or same algorithm--and I see a LOT of rec divers with Shearwaters--you could agree on the same gradient factors (or equivalently in Rec mode, conservatism setting).

 

[KenGordon]

No, because a basic assumption of recreational diving is that you always have immediate access to the surface.

At 40m you do not have immediate access to the surface.

Consider the relative risks. Being out of gas, and unable to get more from a buddy, at 40m is a very bad place. Having a deco obligation and being at risk of running out at 6m (assuming the mystery diver had no gas plan) is not as bad.

The issue is not the deco, it is not having a proper gas plan, communicating that with the buddy and sticking together.