How would you do this dive ...

[MXGratefulDiver]

What we were taught when we did the deco stuff during Rec Triox (which I think is basically the deco stuff for T1) was to start with Decoplanner (he didn't discuss what gradient factor settings). Add the deep stops, pad the stops at gas switches (O2 window) and adjust the shallow stops for surface factors.

It looked so much like the exercises we did last weekend in the Ratio deco seminar that it left me wanting to run some profiles both ways and see just how different the answers would be.

That's what we did at the ratio deco workshop Scott hosted prior to our Trimix class ... we had laptops with Decoplanner and V-planner on them, and we'd run profiles on each using various conservancy factors. Decoplanner is definitely a closer "fit" to the ratio deco profile ... V-planner seems to skimp on the deep stops, even with a conservatism factor of +2.

I had read somewhere that GUE had switched from trying to make a sigmoid curve out of each segment to doing the stops as linear stops, but we were taught, as I said, to add to the gas switch stops.

That's consistent with my conversations with some of the local GUE tech guys ...

... Bob (Grateful Diver)

 

[rjack321]

What we were taught when we did the deco stuff during Rec Triox (which I think is basically the deco stuff for T1) was to start with Decoplanner (he didn't discuss what gradient factor settings). Add the deep stops, pad the stops at gas switches (O2 window) and adjust the shallow stops for surface factors.

30/85 was standard 3 years ago. But that was before the VPM + Buhlmann version of decoplanner came out. I don't know if GUE still has a "reference algorithm" or not. Based on what I've heard from various buddies over the last year or 2, the general deal is:
Take 30/85 buhlmann
Take VPM
Take the RD rules
Take deep stop rules
Take experience
Take environment

Mix well while adding a pinch of voodoo and poof a schedule.

Some of us end up weighting some of those factors a bit more than others based on era and instructor. I end up discussing and agreeing on general schedules even with longtime buddies pre-dive, its part of GUE EDGE afterall

 

[ScubaAndDreams]

Richard ... pretty much the type of info I'm looking for ... not procedure so much as thought process.

Monkseal ... what do you mean by this?

It seems to suggest something I'm sure you didn't mean (EAN50 switch at 120). Everything else you posted is very compatible with what I was taught ...

... Bob (Grateful Diver)

He means that half of the time he has on the Nitrox 50 bottle/segment (70-30ft) he does in the 120-80 segment on backgas/a 120 bottle (35/25).

So if he had 10 mins in the 70-30 segment (however you want to distribute that..(S curve vs linear) then he does 5 mins in the 120-80 segment.

 

[amascuba]

Richard ... pretty much the type of info I'm looking for ... not procedure so much as thought process.

Monkseal ... what do you mean by this?

It seems to suggest something I'm sure you didn't mean (EAN50 switch at 120). Everything else you posted is very compatible with what I was taught ...

... Bob (Grateful Diver)

I believe he was referring to taking half of his deco time for the 70-30 ft stops and moving the time to the 120-80ft stops.

Such as taking 20 minutes for the 70 - 30ft stops and taking 10 minutes of that and distributing it across the 120-80 ft stops. The 50% switch still occurs at 70ft.

 

[rjack321]

I believe he was referring to taking half of his deco time for the 70-30 ft stops and moving the time to the 120-80ft stops.

Such as taking 20 minutes for the 70 - 30ft stops and taking 10 minutes of that and distributing it across the 120-80 ft stops. The 50% switch still occurs at 70ft.

Ack no. Deep stops are not established by removing time from the 50% time. Never, ever - at least not by GUE or other DIR-like instructors that I know.

 

[amascuba]

Ack no. Deep stops are not established by removing time from the 50% time. Never, ever - at least not by GUE or other DIR-like instructors that I know.

I wouldn't take away time from the 50% segment, but that's how I interpreted what Monkseal was saying.

 

[rjack321]

I'm only T1 but this is the way I was taught to establish deep stops. Doesn't exactly apply to Bob's example dive...

30ft per min up to 75% of depth
75 to 50% of depth 1 min per 10ft
50% of depth 3 min per 10ft

Except on a 160ft dive don't bother with a 3 min deep stop at 80ft, just keep on going to the 50% bottle.

In practice this has evolved to:
1) 30ft/min up to 2 ATAs above the bottom, round down 10ft
2) 1 min deep stops per 10ft up to 50% of depth
3) 2 min deep stop(s) at 50% of depth (assuming 50% deco time is <30 mins which it is)
4) switch

 

[rjack321]

I wouldn't take away time from the 50% segment, but that's how I interpreted what Monkseal was saying.

Monkseal typically has great english but I agree its a bit confusing.

 

[JeffG]

I wouldn't take away time from the 50% segment, but that's how I interpreted what Monkseal was saying.

Which wouldn't make any sense, from a decompression viewpoint.

 

[MXGratefulDiver]

He means that half of the time he has on the Nitrox 50 bottle/segment (70-30ft) he does in the 120-80 segment on backgas/a 120 bottle (35/25).

So if he had 10 mins in the 70-30 segment (however you want to distribute that..(S curve vs linear) then he does 5 mins in the 120-80 segment.

Ah ... got it. That makes sense.

... Bob (Grateful Diver)