Padi Advanced OW - Deep stops??

[KenGordon]

This thread started by asking about deep stops for recreational diving. Deep stops are not indicated. No stop diving do not require any stops, regardless of algorithm chosen. Deco diving is another topic

How do you determine if a stop is required? The recent discussion was about how the GF lo affects those no stop dives. That is pertinent to anyone doing no stop dives with a GF computer.

 

[scubadada]

Hi, thanks Ken,

I have the Dive Rite Nitek Q, the GF lo does not affect the NDL, it is controlled entirely by the GF hi. I understand that results may be affected by how the algorithm is implemented.

Best, Craig

 

[KenGordon]

Hi, thanks Ken,

I have the Dive Rite Nitek Q, the GF lo does not affect the NDL, it is controlled entirely by the GF hi. I understand that results may be affected by how the algorithm is implemented.

Best, Craig

Could you try an actual square dive with it? Set a wide GF like 10/90 and see what happens in the water compared to Multideco. Do something like 16 minutes at 100 ft which most tables would call a no stop dive and then a proper ascent (no dawdling).

Dive Rite do not seem to offer planner software so I cannot try out their implementation.

 

[stuartv]

Which implementation is different? One thing put forward to support the superiority of GF computers over proprietary ones is the supposedly open nature of the algorithm. If the planners do not produce consistent results then when you dive the plan how can you expect it to line up with your dive computer?

Multi-Deco and PastoDeco both give a stop based on GF Lo. Subsurface does not. And, I ran a dive simulation on my SeaBear H3 computer. It also does not give a stop based on the GF Lo.

As far as the open nature, I again note that this fine point is only relevant for the small window during a dive where GF Hi does not dictate a stop, but GF Lo does (or would, if used in that way).

When I have a few minutes, I want to re-read Baker's paper on GF and see if his original work actually specifies this detail regarding how the algorithm is to be implemented. I also have a friend who knows and trains with Mark Powell. I think I will get my friend to ask him about his thoughts on this as well.

 

[EFX]

This thread started by asking about deep stops for recreational diving. Deep stops are not indicated. No stop diving do not require any stops, regardless of algorithm chosen. Deco diving is another topic

RGBM can call for a deep stop even though the NDL was not exceeded. I did several dives with my Mares Puck to within 5 minutes of NDL. On one of those dives the computer called for a 1 minute stop at 48 feet. I believe this is what the OP was thinking of. Deco stops are not indicated because the OP was asking in reference to AOW training. My guess is that other computers for rec diving have GF-Lo's set so high that dives within NDL won't call for deep stops. Are the GF-Lo's adjustable on any of these computers?

 

[stuartv]

RGBM can call for a deep stop even though the NDL was not exceeded. I did several dives with my Mares Puck to within 5 minutes of NDL. On one of those dives the computer called for a 1 minute stop at 48 feet. I believe this is what the OP was thinking of. Deco stops are not indicated because the OP was asking in reference to AOW training. My guess is that other computers for rec diving have GF-Lo's set so high that dives within NDL won't call for deep stops. Are the GF-Lo's adjustable on any of these computers?

The seems like a non sequitur.

"An algorithm can call for a stop even though the No Stop limit was not exceeded."

If an algorithm calls for a stop, then, by definition, hasn't the No Stop limit (aka NDL) been exceeded?

Perhaps you mean that some computers have a setting for an optional Deep Stop, which is completely outside of the computer's deco algorithm. I.e. it's not part of RGBM or Buhlmann or any other algorithm. It's just something the computer lets you do in addition to the algorithm. And it's purely optional. And, according to the latest deco theory work, actually increases the possibility of DCS (i.e. it's bad, not good).

 

[scubadada]

RGBM can call for a deep stop even though the NDL was not exceeded. I did several dives with my Mares Puck to within 5 minutes of NDL. On one of those dives the computer called for a 1 minute stop at 48 feet. I believe this is what the OP was thinking of. Deco stops are not indicated because the OP was asking in reference to AOW training. My guess is that other computers for rec diving have GF-Lo's set so high that dives within NDL won't call for deep stops. Are the GF-Lo's adjustable on any of these computers?

Many dive computers have a deep stop option that can be turned on or off. It only works for a no stop dive. The Oceanic version gives you a 2 minute stop at half the maximal depth. Just like the SS, there is no penalty for skipping the DS

 

[EFX]

The seems like a non sequitur. "An algorithm can call for a stop even though the No Stop limit was not exceeded." If an algorithm calls for a stop, then, by definition, hasn't the No Stop limit (aka NDL) been exceeded?

Perhaps you mean that some computers have a setting for an optional Deep Stop, which is completely outside of the computer's deco algorithm. I.e. it's not part of RGBM or Buhlmann or any other algorithm. It's just something the computer lets you do in addition to the algorithm. And it's purely optional. And, according to the latest deco theory work, actually increases the possibility of DCS (i.e. it's bad, not good).

Selecting deep stops on the Mares Puck is not an option. It is built into the algorithm. Here is what the user's manual says:

"To minimize the likelihood of critical bubble seed formation, in the case of decompression dives or dives close to the no-deco limit, PUCK prompts for a series of one-minute deep stops at different depths depending on the dive profile."

It appears that RGBM has created a paradoxical situation. However, keep in mind that the definition for NDL (aka No Stop Dive) was created before bubble models and notions of doing deep stops. Even the term "no stop dive" is misleading because of SS's which are just non-mandatory decompression stops.

 

[scubadada]

Selecting deep stops on the Mares Puck is not an option. It is built into the algorithm. Here is what the user's manual says:

"To minimize the likelihood of critical bubble seed formation, in the case of decompression dives or dives close to the no-deco limit, PUCK prompts for a series of one-minute deep stops at different depths depending on the dive profile."

It appears that RGBM has created a paradoxical situation. However, keep in mind that the definition for NDL (aka No Stop Dive) was created before bubble models and notions of doing deep stops. Even the term "no stop dive" is misleading because of SS's which are just non-mandatory decompression stops.

Are you penalized if you do not complete the deep stops on your Mares computer? Are you penalized if you do not do your safety stop?

As above, there is no penalty for skipping the optional deep stop or the safety stop on my Oceanic computers.

 

[EFX]

Are you penalized if you do not complete the deep stops on your Mares computer? Are you penalized if you do not do your safety stop?

As above, there is no penalty for skipping the optional deep stop or the safety stop on my Oceanic computers.

Missing deep or deco stops will lock you out of air and nitrox modes for 24 hours. It will only function as a bottom timer during that period. The algorithm is not RGBM. It is Mares-RGBM. Missing SS's does not lock you out. The manual doesn't say if you will be penalized. It makes sense that the Oceanic won't penalize you since deep stops are an option. Deep stops are mandatory for the Puck.