GUE Rec Ascent Profile

[David Novo]

In any case, I just wanted to point out that you should consider the entire (recommended) ascent strategy if you want to compare it to any Buhlmann + GF / VPM / whatever model.

In a MDL setting, if you consider Buhlmann with GFs (with a 0 stop length at any stop, including the point where GFlo is reached), it seems to me you should just change your ascent speed at the point where GFlo is reached. If you are moving from 9m/min to 3m/min and then to 1m/min, it does not fit the pattern.

 

[wstorms]

well I don't have the GUE deco planner, but if I run Pasto with Buhlmann 20/85, 30 minutes @ 30 meter using EAN32 I get this:
12m 1 min
9m 1 min
6m 1 min
3 m 4 min

Let's assume the average depth is actually 30 meter, so we include a 1 minute stop at 15 meter to match the ascent protocol. In addition, I spread out the last minutes over the remaining ascent. Now it looks like this:
15 m 1 min
12m 1 min
9m 1 min
6m 1 min
3 m 1 min (Pasto still gives 4 minutes here)
2m 1 min
1m 1 min
0 m 1 min

Pretty spot on if you ask me. Question remains why. Is the ascent procedure made with GF20/85 in mind? Does it simply work?
For comparison: if I use GF 20/100 the 3 meter stop is only 1 minute, even without the 15 meter stop.

 

[David Novo]

well I don't have the GUE deco planner, but if I run Pasto with Buhlmann 20/85, 30 minutes @ 30 meter using EAN32 I get this:
12m 1 min
9m 1 min
6m 1 min
3 m 4 min

Let's assume the average depth is actually 30 meter, so we include a 1 minute stop at 15 meter to match the ascent protocol. In addition, I spread out the last minutes over the remaining ascent. Now it looks like this:
15 m 1 min
12m 1 min
9m 1 min
6m 1 min
3 m 1 min (Pasto still gives 4 minutes here)
2m 1 min
1m 1 min
0 m 1 min

Pretty spot on if you ask me. Question remains why. Is the ascent procedure made with GF20/85 in mind? Does it simply work?
For comparison: if I use GF 20/100 the 3 meter stop is only 1 minute, even without the 15 meter stop.

Very interesting results. I wonder if the rec ascent protocol will change with the latest research advocating higher GFlo...

 

[boulderjohn]

About a year ago, I researched NDL ascent profiles. I contacted GUE headquarters to ask about theirs, and I was assigned someone who acted as a spokesperson. Here is some of what I was told.

1. The basis for the approach is the belief that ascents should be slower in the shallower part of the ascent.
2. The basis is NOT because of a belief in a deep stops protocol for NDL dives.
3. A point half way in the ascent was chosen because it is easy to compute half.
4. Doing multiple stops forces a slower ascent rate.
5. Doing multiple stops mirrors what is done on decompressions stops and thus provides consistency.

 

[tursiops]

Very interesting results. I wonder if the rec ascent protocol will change with the latest research advocating higher GFlo...

I hope not, since NDL dives are not sensitive to the choice of GF-low.

 

[wstorms]

hmn the plot tickens...
I ran the same profile but this time using tx 30/30 as gas.
TTS for GF20/85 is 13 minutes (was 7) and for GF20/100 it is 7 minutes (as opposed to 4). Especially the 13 minutes is a lot harder to map on the ascent protocol.

 

[David Novo]

I hope not, since NDL dives are not sensitive to the choice of GF-low.

I understand your point. However if the ascent profile was linked to Buhlmann with GFs, the point at which you change your ascent speed would change with GFlo.

According to what @boulderjohn posted it is not, so it is irrelevant.

 

[arthurng311]

This is from GUE deco planner
If you strictly follow a GUE MDL ascent profile, the stops will be slightly redistributed but the total dive time will be the same:
32 mins arrive at 15m
33 mins arrive at 12m
34 mins arrive at 9m
35 mins arrive at 6m
36 mins arrive at 3m
37 mins arrive at surface

When i took fundamentals, my instructor Gideon told us the reason they use this ascent profile is because it will let us get used to ascending at multiple rates and also holding stops, which will make our pathways to tech courses easier, hope this helps.

 

[NAM001]

Interesting question, makes me wonder where other agencies got the 3 min @ 5 meter safety stop from..

Its IMO one of these one rule fits all and under the worst conditions for a brand new diver. I just used this example in another thread. You have a new diver that conforms to the rules of no deeper than 60 ft. he stays long enough to become saturated at 60 ft. or 3 atm. he then goes to 20 ft at some unkown rate. and arrives at 20 ft holding a line. hew has gone from 3 atm to about 1.5 atm or slightly less depending on unknown ascent rate. the CYA protocol is to do a safety stop to effectively alter the ascent rate form say 30 seconds to 3 or more minutes so the diver avoids problems arriving at the surface too early. I use a shearwater and the info available such as GF values allows me to control my SS time and ascent rates. most computers do not have this and again this 3 minute rule thing is really archaic from the days of watch and depth gage divers. the foundations of the stop is still good but the reasons are moot because of technology today. In other words do a SS for 3-5 minutes because you dont have the info needed to make a good decision. Now computers have that info available. Courses that taught under the premis of computers not being required has to continue this possible depth gage watch protocol. course equipment standards controls much of the course content. Is it not GUE that will not allow a shearwater teric to be used because of no access to gf settings at depth?

 

[tursiops]

Its IMO one of these one rule fits all and under the worst conditions for a brand new diver. I just used this example in another thread. You have a new diver that conforms to the rules of no deeper than 60 ft. he stays long enough to become saturated at 60 ft. or 3 atm. he then goes to 20 ft at some unkown rate. and arrives at 20 ft holding a line. hew has gone from 3 atm to about 1.5 atm or slightly less depending on unknown ascent rate. the CYA protocol is to do a safety stop to effectively alter the ascent rate form say 30 seconds to 3 or more minutes so the diver avoids problems arriving at the surface too early. I use a shearwater and the info available such as GF values allows me to control my SS time and ascent rates. most computers do not have this and again this 3 minute rule thing is really archaic from the days of watch and depth gage divers. the foundations of the stop is still good but the reasons are moot because of technology today. In other words do a SS for 3-5 minutes because you dont have the info needed to make a good decision. Now computers have that info available. Courses that taught under the premis of computers not being required has to continue this possible depth gage watch protocol. course equipment standards controls much of the course content. Is it not GUE that will not allow a shearwater teric to be used because of no access to gf settings at depth?

Most people do NOT have Shearwaters....the safety stop is still a GOOD idea.