GUE lost deco bottle procedure

[colablikje]

Hi, I would like to understand how the GUE procedure works when one team members has lost his deco bottle and it is time to perform deco.
As I understand, teammates then share their deco bottle with the diver who lost his deco bottle, but I am not clear as to how this is done. Let's say you need to do 10 minutes of deco. Do you then share a bottle for 5 minutes and then switch with the other teammate? That might work, but then the team would have to stay 15 minutes until each has had 10 minutes at a deco bottle. Or perhaps you switch after 2 or 3 minutes?
So, I would like to know how it is decided when to switch (after 2 minutes? 3 minutes? 5 minutes?) and whether that is standardized or not.

 

[CptTightPants21]

It depends on the dive, team size, and which bottle was lost/broken.

If the 50% bottle was lost:
Team of 2
Maintain schedule with each diver breathing 50% at alternating stops. Diver 1 @ 70, 50, 30, Diver 2 at 60 and 40
At 20ft stop either switch to 100% and increase deco time 1.5x or if 50% is only deco gas, alternate 50% between divers every 5 min and double 20ft stop time so that each diver spends the initial planned deco time actually breathing 50%

With team of 3
Same procedure, but now you have two different buddies providing 50% and each diver is only missing every third stop

If 100% bottle is lost,
Share O2 in 5 min intervals, extend stop time 1.5x. If you have 50% bottle, breathe 50% when not on the 100%

 

[michael-fisch]

I have always taught next deeper gas twice as long, and switch the right gas between the divers.
Boils down to:
Diver 1 right gas, Diver 2 next deeper gas for 2/3 of the stop time
switch right gas
Diver 1 next deeper gas, Diver 2 right gas for 2/3 of the stop time
ascent to next stop and continue.

Deco time and gas requirements increase by 1/3 compared to everything working out perfectly, and all of you should be able to get out of the water healthy.
Padding the ascent times from the last stop cannot hurt and should be done if possible, but are probably not necessary.

Michael

 

[colablikje]

If 100% bottle is lost,
Share O2 in 5 min intervals, extend stop time 1.5x. If you have 50% bottle, breathe 50% when not on the 100%

Is that 5 minute standard, or do you refer to "5" because that is half of 10. So, if you had a 6 minute stop @20, would you then use 3 minute intervals, for example?

 

[CptTightPants21]

Is that 5 minute standard, or do you refer to "5" because that is half of 10. So, if you had a 6 minute stop @20, would you then use 3 minute intervals, for example?

Intervals of 5 is the norm, easier to multiply, easier to utilize while planning, and easier to keep track of.. Although if it was only 6 min or if it was the last 6 from a deco of say 16 min I would wrap up and do the full 6. No reason to get cute with 1 min.

 

[rjack321]

If the 50% bottle was lost:
Team of 2
Maintain schedule with each diver breathing 50% at alternating stops. Diver 1 @ 70, 50, 30, Diver 2 at 60 and 40
At 20ft stop either switch to 100% and increase deco time 1.5x or if 50% is only deco gas, alternate 50% between divers every 5 min and double 20ft stop time so that each diver spends the initial planned deco time actually breathing 50%

Who taught you this? 20mins of deco - whooopdie do.
45mins of 50% time and you only did the equivalent of about 30mins or worse if you are on 15/55 for half the stops. You're breaking some significant ceilings.

This is not how my Tech1 was taught - at all. However that was long ago and the current protocol I am not privy to. (I was taught that you both do 1.5x of the time at each stop but with 1/2 of that time on backgas which roughly counts for half as much deco as the 50% So if its supposed to be a 4min stop we do 6 total with 3 on 50% and 3 on backgas. The 3 backgas mins count as 1.5mins of deco gas time plus the original 3mins of 50% so you "did" 4.5 mins of deco. Otherwise you are blowing off stops, maybe no big deal for short decos but it doesnt scale up at all)

 

[lermontov]

It depends on the dive, team size, and which bottle was lost/broken.


Maintain schedule with each diver breathing 50% at alternating stops. Diver 1 @ 70, 50, 30, Diver 2 at 60 and 40

Is this the GUE protocol?

 

[CptTightPants21]

Who taught you this? 20mins of deco - whooopdie do.
45mins of 50% time and you only did the equivalent of about 30mins or worse if you are on 15/55 for half the stops. You're breaking some significant ceilings.

This is not how my Tech1 was taught - at all. However that was long ago and the current protocol I am not privy to. (I was taught that you both do 1.5x of the time at each stop but with 1/2 of that time on backgas which roughly counts for half as much deco as the 50% So if its supposed to be a 4min stop we do 6 total with 3 on 50% and 3 on backgas. The 3 backgas mins count as 1.5mins of deco gas time plus the original 3mins of 50% so you "did" 4.5 mins of deco. Otherwise you are blowing off stops, maybe no big deal for short decos but it doesnt scale up at all)

It is in the current SOP (v3) and how I was taught in my Tech 1.
Do you also do modified Deco Planner with the smooth stop schedule? It appears that the standard has shifted from spending more time at depth to getting shallower and spending more time on the pure O2.

It depends on the dive parameters, but it would be a pretty big dive to get to 45 min of 50%. - 9s on Mod DP.

I ran a few scenarios just to play. I run 50/80 GF and would need to do a dive to to 225ft (67.5m) for 40 min to get around those numbers with a bottle of O2 and 50%, but the bottom gas and even the O2 cuft numbers were massive. I use a .7 SAC bottom rate and a .6 deco SAC rate for planning. Bottom gas requirements would have been around 250-310 cuft plus - 50-60cuft each deco tanks just on plan with no account for reserve--run times and deco would have been slightly longer if using 20/85.

Dropping the planned dive time to 30-35 min alleviated a bunch of the pressure, but adding a third deco gas of 35/25 shaved 20-25 min off of deco and made the reserve gas calculations much more palatable. Doing both moved the 50% time into the 30-35 min range (7s)--It made the distribution of the stops more equal and you are switching between 35% O2 and 50% instead of 15% and 50%

Basically what I am saying is that your scenario isn't practical. If you want to do a dive with 15/55 and rack up ~45 min of 50%. Deco times and gas reserves will dictate a third deco gas. If you plan on doing that dive with just 50% and 100% then your bottom time will be in the 25-28 min range and the time spent on 50% will be in the 25 min rage and you make up the deco difference by spending more time on pure O2.

 

[PfcAJ]

I'm a fan of "share the gas and extend stops 1.5x."

I agree with rjack, maintaining the same ascent schedule but not breathing the deco gas the for the same amount of time isn't good and doesn't scale. CptTightPants is right that it is tough to get 45mins of 50%, but its not unheard of. I'll get numbers close to that (40mins on 50%, 50mins on 100%) in the ocean, and deco times way past that in caves, even with a 35/25 deco bottle.

 

[rjack321]

If we do a 25min dive at 240 with 50/80 GF I get 29mins on 50% and 39mins on O2.
Your way:
Diver1 does 3+5+11 = 19mins
Diver2 does 3+7 = 10mins

Diver2 is basically doing 1/3rd as much 50% as required, that's bad news. Personally I'd be bent at the 20ft stop and now I'm doing IWR for that O2 time. Since we only plan for "1 major failure" we both have plenty of backgas and there's really no good reason I see to rush through the 50% stops with diver2 essentially skipping 3 of the 5.