deco buddy

[JeffG]

Jeff is a man of few keystrokes thats how he racks up over 3600 posts

Thats right. That and the water cooler.


BTW...What did the guys do in real life? (Ie the scenario that prompted this thread)

 

[wedivebc]

Thats right. That and the water cooler.


BTW...What did the guys do in real life? (Ie the scenario that prompted this thread)

I was on the boat when this happened (yes in real life) I only (barely) knew one of the participants and I was with another team of people I knew and we finished our dive together thank you.
When they came up and were unconcerned about the tardy team member since he was going to bwe 10-15minutes longer I went and had lunch on the boat. After I finished I noticed he was still down there after 20 minutes so I went to keep him company. He indicated he had gone through both his and his buddy's deco gas and was on back gas so I got my 50% from the boat and gave it to him. After 5 min or so I wrote on a slate "how long?" He was shaking so bad that he could not reply to which I suggested he surface and take O2 on the boat.
I knew the dive profile and I was sure he had cleared deco based on time he spent at depth so he agreed. I had to help him out of his rig in the water because he was so cold.
Yes he was riding his VR3 on this dive, and had screwed up inputting the enriched O2 gas so I guess the computer thought he had done all the deco on back gas.
I was not going to state this publicly for fear of embarrasing anyone but I feel there is a lesson to be learned here and why shouldn't all share the lesson learned.
I am of the school that you do anything you can to help your buddy short of endangering yourself. My dive buddys know that and if I am diving with someone new I usually cover these what ifs, pre dive. Saves a lot of confusion in the water.

 

[Soggy]

The best lesson there is know your schedule and don't depend on a piece of plastic to feed it to you. If you want to use the plastic to potentially get you out of the watera few minutes faster, fine, but plan your dive and dive your plan. If the computer isn't displaying logical information, assume it is fooked and do your planned schedule.

 

[Diver0001]

First of all, if your buddy runs out of deco gas (and has to switch to a back gas deco contingency), and you continue your deco with your planned gas, you will not be at the same depths at the same time. You would not be able to hand off your deco gas unless you descended back down to his deco level. You do not want to be doing that.....

--Matt

This would depend a lot on the gas and the depth. Assuming a technical nitrox dive using 50% as deco gas you'd need to do something extraordinary to get different ascents deeper than 12 metres using 50% or 32%. Moreover, once you're in the shallow zone (9m and shallower) you can extend your stops for as long as you like without incurring any additional deco. In other words, in that context if your buddy needed to deco out on backgas you would be able to do it on 50% and maintain the same depths and times as your buddy for the whole ascent. Of course you would be clean earlier than your buddy but that would just give you the opportunity to share whatever deco gas you had. If you were using O2 to deco this only gets simplified further.

Without crunching the numbers, it seems pretty obvious to me that the same thing applies to any gas you use to achieve accelerated deco. As long as your MODs are deep enough I can't see why you would get in trouble using a faster gas on a slower schedule..... do you have an example where this doesn't work?

R..

 

[Diver0001]

I was on the boat when this happened (yes in real life) I only (barely) knew one of the participants and I was with another team of people I knew and we finished our dive together thank you.
When they came up and were unconcerned about the tardy team member since he was going to bwe 10-15minutes longer I went and had lunch on the boat. After I finished I noticed he was still down there after 20 minutes so I went to keep him company. He indicated he had gone through both his and his buddy's deco gas and was on back gas so I got my 50% from the boat and gave it to him. After 5 min or so I wrote on a slate "how long?" He was shaking so bad that he could not reply to which I suggested he surface and take O2 on the boat.
I knew the dive profile and I was sure he had cleared deco based on time he spent at depth so he agreed. I had to help him out of his rig in the water because he was so cold.
Yes he was riding his VR3 on this dive, and had screwed up inputting the enriched O2 gas so I guess the computer thought he had done all the deco on back gas.
I was not going to state this publicly for fear of embarrasing anyone but I feel there is a lesson to be learned here and why shouldn't all share the lesson learned.
I am of the school that you do anything you can to help your buddy short of endangering yourself. My dive buddys know that and if I am diving with someone new I usually cover these what ifs, pre dive. Saves a lot of confusion in the water.

A few things cross my mind upon reading this.

- First and foremost, I hope *every* boat has a Dave like you on board.
- His buddies were irresponsible, lazy, inattentive clowns. I can only hope that they watched you save their friend and feel deeply deeply ashamed of their actions. I hope they choose to learn from this experience .....
- My feeling about the mistake made by the diver in question is ambiguous. On the one hand I hope it freaked him out enough that he learned his lesson and on the other hand I can empathize with him doing tonnes of extra deco and playing it safe. It also irritates me. He must be trained for the kind of diving he's doing but he's not following his training and there is a *reason* that we are trained to go about this a certain way.... Third (or fourth), I personally don't agree with diving the computer and certainly not with *riding* the computer on a deco dive. The computer is at best a backup and at worst a distraction. To ride the computer on a deco dive is an unforgivable sin. I know there is a new generation of divers who are too "plugged in" to trust the tables but if he's going to make tek dives he needs to do better.

I'm curious. What happened (or was said) once you got back on the boat?

R..

 

[wedivebc]

I'm curious. What happened (or was said) once you got back on the boat?

R..

I made my thoughts on this known back on the boat. I am hoping this thread will have an impact as well since I will be suggesting the parties involved read it.

 

[matt_unique]

This would depend a lot on the gas and the depth. Assuming a technical nitrox dive using 50% as deco gas you'd need to do something extraordinary to get different ascents deeper than 12 metres using 50% or 32%. Moreover, once you're in the shallow zone (9m and shallower) you can extend your stops for as long as you like without incurring any additional deco. In other words, in that context if your buddy needed to deco out on backgas you would be able to do it on 50% and maintain the same depths and times as your buddy for the whole ascent. Of course you would be clean earlier than your buddy but that would just give you the opportunity to share whatever deco gas you had. If you were using O2 to deco this only gets simplified further.

Without crunching the numbers, it seems pretty obvious to me that the same thing applies to any gas you use to achieve accelerated deco. As long as your MODs are deep enough I can't see why you would get in trouble using a faster gas on a slower schedule..... do you have an example where this doesn't work?

R..

When you refer to "different ascents" above, are you referring to depth or time? The required depths would be the same but the times would vary based on the gas of course. Assuming both divers were using the same back gas, had the same max depth, time, etc.

I don't disagree...longer deco stops on gas with a higher 02 content than your backgas will not result in added DCS risk unless the water temp poses a risk. You could certainly choose to extend your stop times or choose to make ballpark calculations on the fly in sharing your deco gas to stay with your buddy if this was your preference.

--Matt

 

[Diver0001]

When you refer to "different ascents" above, are you referring to depth or time? The required depths would be the same but the times would vary based on the gas of course. Assuming both divers were using the same back gas, had the same max depth, time, etc.

I don't disagree...longer deco stops on gas with a higher 02 content than your backgas will not result in added DCS risk unless the water temp poses a risk. You could certainly choose to extend your stop times or choose to make ballpark calculations on the fly in sharing your deco gas to stay with your buddy if this was your preference.

--Matt

Sounds like you got the gist of what I meant.

R..

 

[CJ-62]

As another diver on the same boat, different team (no major issues with my dives that day), there was a fact or two that did not get sorted out until later.

While the diver, "Chilly", did miss switching gases on his computer and over stayed his welcome, his computer displayed deco information for the switch he never made and counted down time for his backgas. Restated, the VR3 he was using displayed 15 minutes countdown at his last deco stop but was ticking off 1 "computer" minute for every 4 real minutes.

He was not really riding his computer, but was trusting it to display the passage of time correctly. He did not utilize secondary means of time control or trust his gas usage to indicate that more than 5 minutes had elapsed since his buddy surfaced and the support diver (BTW, great job Dave) showed up.

The dive profile had been discussed between the team using a laptop based deco planner, but at depth the affected diver had gone slightly deeper (the planned depth) than the other. The buddy had a drysuit leak that assisted in his decision to exit the water promptly. Additionally one diver used a Nitek HE while the other used the VR3. This slight delta in profile and computer allowed the first diver to exit thinking the second was a minute or two behind him. This was a repetitive dive/multi-day scenario which lent itself to trying to keep the computers happy (another thread in itself).

I am not contending that the dive team didn't make mistakes, or that room for improvement does not exist. I only offer these additional facts to show how:
1. It is never as simple as it seems.
2. Small issues cascade into problems of ever increasing magnitude.
3. Never trust any single system/component for your survival. (Environmental protection is an exception for me, I never bring along an extra drysuit on my dives, but I got one in the truck!)
4. At some point you may have to ignore your gauges and go with your head.

Respectfully submitted.
"Cannonball Diver"

 

[Diver0001]

so CJ are you saying that his computer actually failed?

R..