Do any Tec-Rec (or light deco) divers use GTR?

[rongoodman]

I've been wondering what the hell gtr is too but thought I'd be the idiot if I ask. Will someone explain what gtr is.

"GTR is similar to No Decompression Limit (NDL) in that it is the time, in minutes, that you can remain at the current depth until a direct ascent would result in surfacing with the reserve pressure remaining."

 

[Jay]

I voted No in the poll. I think you're trying to overcomplicate the concept of GTR for a small increase in utility. Safety stops don't use enough gas to worry about, unless you begin one with a near empty tank, in addition to the fact that they're optional for recreational dives. In any event, I don't see that it merits three separate threads.

Thanks for the reply. Hope it's OK if I paste the core of it into the Poll thread?

As for three threads on same topic; this question here/this thread is not the same but is related to the Poll thread. It's to a different forum section for a specific reason. It's a hypothesised flow-on question from the poll. It's a different question than the poll. Given the voting composition in the poll I don't think it was an unreasonable one.

I guess you're also referring to my thread a month back about GTS, and weaving NDL into it etc. That thread was a cluster and doomed from the start. There's no way I could clean it up (already pretty illegible post the strike-outs within the 24hr window) and succinctly ask the question that should have been asked (i.e. the Q in the poll). Sure, you can try and hit me on that one, but perhaps hit me for a cluster thread/concept (as the replies did) as opposed to a repetitive thread.

Back to something more substantive if you'd like to share your opinion on at some point; by definition Shearwater Tec or (any type of deco) divers can't use GTR until all deco stops are cleared. Other PPS related brands + SP can use GTR - to what extent and how they're used by Tec, Tec-Rec divers re GTR I don't know (exc one reply above). I see from your posts you've also got a Teric coming and are have moved from a non-AI Perdix. Assuming you're AI'ing your Teric, one aspect of my proposal in the poll was to make GTR work for single gas across all modes. Would that aspect aid the type of diving you do? Perhaps give the Teric a spin for a while and feel free to revive this thread or the Poll one and copy this paragraph into it so it has a legible flow.

 

[Diving Dubai]

GTD...

I prefer TTD (Time to Die)

In reality it's only "useful" as a guide for rec divers on a single tank, who haven't attained the experience in knowing from experience based on their depth and gas pressure, how long they have left. It can be useful as a guide for them to manage their gas vs dive time (go shallower)

For multiple tanks, the methods only monitor that tank you're breathing from and don't take into account all the gas strapped to you. It's only a rough guide

If you don't know you SAC, can't do the quick mental math on gas pressure/consumption to get your remaining time you shouldn't be engaged in non NDL diving at all

 

[boulderjohn]

I am apparently losing reading comprehension ability in my old age, because I am confused as Hell and could use some explanations.

1. Am I seeing a breakdown of divers into 3 groups--recreational, technical, and tec-rec? If so, what is tec-rec?
2. I seem to be seeing references to recreational divers doing multiple stops and needing to know if they have enough gas to do those multiple stops. Why are recreational divers doing multiple stops, except in the case of emergency (unplanned) decompression?
3. Is doing multiple planned stops on a recreational dive what is being referred to as tec-rec?
4. About 20 years ago, I purchased my first computer, a Suunto Cobra. It was air integrated, and it told me how much time I had to dive at my present gas usage rate before I hit my reserve. It also told me how long it would take me to get to the surface, given any decompression obligations I would have. It made sense to me to have the remaining gas time greater than the time required to get to the surface. What exactly is being requested that would be different from that feature?

 

[Jay]

I am apparently losing reading comprehension ability in my old age, because I am confused as Hell and could use some explanations.

1. Am I seeing a breakdown of divers into 3 groups--recreational, technical, and tec-rec? If so, what is tec-rec?
2. I seem to be seeing references to recreational divers doing multiple stops and needing to know if they have enough gas to do those multiple stops. Why are recreational divers doing multiple stops, except in the case of emergency (unplanned) decompression?
3. Is doing multiple planned stops on a recreational dive what is being referred to as tec-rec?
4. About 20 years ago, I purchased my first computer, a Suunto Cobra. It was air integrated, and it told me how much time I had to dive at my present gas usage rate before I hit my reserve. It also told me how long it would take me to get to the surface, given any decompression obligations I would have. It made sense to me to have the remaining gas time greater than the time required to get to the surface. What exactly is being requested that would be different from that feature?

For Q2 & 4, if you click the Poll linked in the OP to this thread it will explain a lot and keep the topics somewhat on topic and although the votes are stacked against the poll there's only one voter there who's detailed his rationale, and one in this thread who also voted there.

For Q1 & 3. It was defined to me as "up to 15 minutes or so of real deco. (there are a lot of us)" and that was in response to me dividing divers into Tec and Rec.

 

[boulderjohn]

For Q2 & 4, if you click the Poll linked in the OP to this thread it will explain a lot and keep the topics somewhat on topic and although the votes are stacked against the poll there's only one voter there who's detailed his rationale, and one in this thread who also voted there.

For Q1 & 3. It was defined to me as "up to 15 minutes or so of real deco. (there are a lot of us)" and that was in response to me dividing divers into Tec and Rec.

To me, you are either a technical diver or a recreational diver, and if you are doing 15 minutes of deco (more than is allowed with a PADI Tec 40 certification), then you are either a trained technical diver or a recreational diver pretending to be a technical diver. The difference is very much related to the topic of this thread.

If you are planning to do decompression, then you should understand that decompression stops are different from safety stops because of the increasing danger of missing them. If you miss a safety stop, you will almost certainly be OK in terms of DCS. Every added minute of required decompression adds to the risk of DCS if you have to miss them.

So, if you are going to go into deco intentionally, you need to be very sure you have the gas required to do it. That means more, though, than having the volume of gas required in your tank. It means being sure you will have that necessary volume in case of an unforeseen emergency, such as a regulator failure. If you are breathing off of a single tank and have a nice, comfortable 1,000 PSI still there when you reach a deco stop, that will all end in a hurry if you suddenly have a regulator free flow.

That is why true technical divers do not plan deco unless they have a redundant gas source available for such an emergency.

 

[DanielRJones]

Also what about your buddy who will could also be slupring off your tank at 25l min.
I have a laminated sheet in my wet notes tells me my turn pressure for depths from 20 25 30 35 and 40m using 12l 15l and twin 12l assuming 2 divers at 25l/min with standard ascent and 5min safety stop and getting out at 30bar.
Takes me 2 seconds to look at that before a dive and know when i shoukd be off the bottom

 

[Diving Dubai]

To me, you are either a technical diver or a recreational diver, and if you are doing 15 minutes of deco (more than is allowed with a PADI Tec 40 certification), then you are either a trained technical diver or a recreational diver pretending to be a technical diver. The difference is very much related to the topic of this thread.
.

Sorry. You’re using the PADI Termanology between Rec and Tec. It’s a big world out there with many other respected agencies. Not all have the hard distinguishing line between Tec and Rec, or indeed believe in labels

BSAC for instance teach Deco as part of their second tier cert (rescue in PADI) It’s standard training. BSAC don’t use the term technical until you start trimix and or CCR

So in the BSAC world, I’ m Rec diver qualified for deco (and because of further training), accelerated deco

I do not disagree with the remainder of your post however

 

[rongoodman]

Also what about your buddy who will could also be slupring off your tank at 25l min.

THIS is the downfall of GTR, not the few bar of your reserve you might need to use for a safety stop. It would be nice if it could reflect your required minimum gas, but hard to see how it could be done in any practical sense.

 

[DanielRJones]

The safety stop in gtr on a shearwater is not as issue. You are diving a gf you dont need a safety stop. The safety is built in to the gf. If you want to have a safety stop that is up to you.
Why should a computer put in a aditional 3 min stop into its calcs that is not required.