Perdix "Adaptive" Safety Stop - What's the purpose.

[Roy_W]

Can anyone explain the point of the adaptive Safety Stop option.

Recently I had a dive to 32m for a total of 34minutes, it was a square profile wreck dive.. This was my first dive of this kind with the Perdrix.

I had an initial Deco Stop at 6m for 2 minutes followed by 3m for 3minutes stop ; my Perdrix is set to Medium conservation, so a 40/85 GF. After the mandatory Deco Stop completion the Perdrix then displayed a 5 minute Safety Stop....

I understand that in ADAPT Safety Stop mode any dive below 30m will result in this 5 minute SS but how do you treat this information ? What's the point of the Safety Stop being Adaptive if the only change is the fact that below 30m it changes from 3 to 5 minutes ?

I must admit that it adds a little stress to the final 3m ascent when that SS is flashing yellow even after having completed your mandatory stop...

In fact after reading this I would probably have had the same thoughts if I had set the SS to 1, 3, 5 or adaptive...

Maybe my question should have been , do you follow the computers advice to do a safety stop "after" the completion of the mandatory or do you just ignore it...

It's a semi-newb question as I am only beginning to do dives which require mandatory decos.

Cheers

 

[KenGordon]

Longer and deeper dives lead to more bends. Add some extra deco time, over and above what the model calls for, and you will improve that a bit. A three minute stop for a 20m dive helps a bit, a five minute one for 35m will be a help.

Models are only models. An extra stop isn’t going to hurt.

 

[Jack Hammer]

5 mins deco for a square profiled 34 minute dive at 32m sounds a little light, unless you are doing deco on O2. The 5 minute safety "padding" sounds like a good idea.

 

[RVBldr]

Anytime I'm below 100' my safety stop is 5 min, even if there's no deco, and if doing a deco dive, I'll normally add a 5 min SS, I'm not in that big of a hurry to get out normally and it drops the Surface GF by a decent amount. If doing deco dives, you might want to be running that in TEC mode rather then REC. Tec will clear deco, then start a count up for how long you've been clear of deco. If you haven't already taken a class, TDI Advanced Nitrox/Deco procedures or a like class might be worth it to keep from bending yourself.

 

[Norwegian Cave Diver]

Your "TTS" Time to Surface - should remove any stress and give you a clear indication as to when you are on the surface.

 

[Roy_W]

5 mins deco for a square profiled 34 minute dive at 32m sounds a little light, unless you are doing deco on O2. The 5 minute safety "padding" sounds like a good idea.

Hi Jack,

Sorry, I may have worded thing a little bit incoherently... 34 Minutes was the total dive length, we actually spent about 18 minutes at 32m..The divemaster set us the limit that the first person to reach 5 minutes mandatory deco was the signal to ascend.


Norwegian Cave Diver
I just realised that Shearwater Desktop actually stores the TTS throughout the dive so I can share the profile with you and the TTS.

At around the 18 minutes mark the TTS was 11 minutes which I believe would be the sum of 1minute at 6m + 5 minutes at 3m + the time to surface ~4 minutes + another mysterious value...

At the 28 minute mark the deco are finished , I am around 3m deep and the TTS still has 6minutes remaining..

We can see at the end of the that all decos and even a large part of the safety stop were completed so I am not too worried about the duration but it now leads me to believe that the Shearwater is counting the Safety Stop as part of the TTS.

 

[TheCoolBeans]

The Shearwater doesn’t count the safety stop time as part of the TTS (at least not in OCtec mode)

Safety Stops are optional
Ceiling stops are mandatory

Try the OCtec mode as others suggested.
It’s a lot clearer when you’ve completed mandatory stops and are now ‘deco clear’ and it will start counting up the mins:secs since deco cleared so it’s easy to see when you’ve completed your safety stops too.

 

[Roy_W]

I just realised that it's not easy to read the values in the little squares so I will republish them on order.

As you can see at the 28 minute mark the TTS reads 6 minutes and yet the mandatory Deco's are complete and I am only at 3.5m, it's listing the TTS at 6 minutes and this is why I believe that it is including the Safety Stop in the TTS.

( The mandatory Deco drops to 3 minutes at 3m around the 24 minute mark, I didn't include the image as I don't think its necessary.)

 

[Roy_W]

The Shearwater doesn’t count the safety stop time as part of the TTS (at least not in OCtec mode)

Try the OCtec mode as others suggested.
It’s a lot clearer when you’ve completed mandatory stops and are now ‘deco clear’ and it will start counting up the mins:secs since deco cleared so it’s easy to see when you’ve completed your safety stops too.

Ok, I will start to read up on the OC Tec mode and give it a try...

 

[rongoodman]

I'm a little confused as to why you're combining mandatory deco with safety stops. They're two different things for two different types of dive.