Overshooting NDL and mandatory deco stops

[Blackcrusader]

Respectfully disagree. Many recreational divers do not understand GFs, I didn't before tech training, and I don't think that means that they shouldn't be diving.

Shearwater computers are awesome for many reasons. They have rock solid construction, they have incredibly visible and well organized displays, you can replace the battery easily in the field, and the company provides amazing technical support. Why wouldn't a recreational diver want one of these if they could afford it? A Shearwater, on the other hand, is a terrific dive computer for anyone, even someone who never does more than shallow reef diving within NDLs.

I am not a tec diver. However I was BSAC qualified in sports diving in the 1980's where every dive was a planned deco dive on air. Single tanks. All dives planned on paper first and we brought tables and cards to write on for deco dives. No computers back then. I only do recreational diving now and replaced my Suunto with a Shearwater Perdix. I did not want to have the AI function. I have a cressi2 digital console.

I have done a lot of research on gradient factors and dive with my computer in OC TEC mode. Which means I am responsible for clearing safety stops. The Perdix is not a babysitter. I bought it due to its easy to read screen especially for night dives and low vis dives, also because I do not wear a watch so wasn't interested in the Teric. I do a lot of repeat dives, do in a 12 days of diving I would normally have 36 - 42 dives logged. 3 day dives and some night dives. The Shearwater is much better for divers doing these types of continuous diving as you can see your CNS and other information at hand. I have had one dive in the last 850 dives where I was with an instructor who deliberately went 10 mins past NDL on a 32m dive. I was not happy about it however I was better on air than she was and we both safely did our stops and finished the dive with both of us with more than 80 bar. I have been on dives with many PADI instructors who ignore NDL. I now just stay above NDL and leave them up to their own devices, many are solo certified but they dive with me then think they being solo certified means they can do what they want regardless of their dive buddy not being solo certified.

Fantastic thing is the latest firmware clearly tells you DECO CLEARED when you need to clear deco.

Anyone who says a Shearwater Perdix is not for recreational divers is wrong in my humble opinion.

 

[Blackcrusader]

The default of the system is 30/70. The system provides several settings that are more aggressive than the default. Don’t use the system until you understand how it works�
"

This is the default in my Perdix.

 

[Blackcrusader]

Personally, if I overstayed my NDL by more than 5 minutes, I'd spend the rest of my tank at safety stop depth, surface with some 10-ish bar (~150 psi) left and then ask for the O2 bottle when I got back on the boat. And I'd be looking out for any DCI symptoms.

If I did that I would be in the water for a long long time.

 

[Blackcrusader]

Maybe "aggressive" wasn't the most accurate term, but how about:
...being at 80 feet with only 1075 psi and a 3 minute deco obligation, and then lollygagging another 16 minutes to get to 40 feet?
...and then being at 41 feet with 375 psi and STILL having a 2-min deco obligation?

Thank you for sharing this profile! Really! We were all younger and dumber at one point in our lives. I'll presume your pucker factor was also pretty high when you hit 375?? Nice SAC rate, tho!

Here's me at 25m for 25m mins and 5 mins to zero NDL. 12l tank with 200 bar start. 150 bar after 25 minutes at 25m. It is up to the diver to pay attention to air depth NDL and if they have a good dive buddy that dive buddy might also monitor them and make sure they have enough air. I often dive with people who are no so good on air and bring them up 10m or less to make sure they can finish an hours dive safely rather than them doing only 40 minutes dive because they stayed too deep ( their NDL not an issue ) with their consumption.

 

[Mike1967]

This is the default in my Perdix.

I think someone might have played with it, that's not default

 

[Blackcrusader]

I think someone might have played with it, that's not default

Yes what I meant is it is the default set now in my Perdix in OC TEC mode.
As you can also see I set the safety stop to 6m. Generally I am at 5m taking photos or videos on reefs if I can for the last 10 - 15 minutes of my dive and I often come up with deco cleared show plus 10 minutes or more.

I like to do lots of diving when on dive vacations. Most dives in one vacation was 58 dives....
Mostly I do 35 - 40 dives minimum per dive vacation and I do several a year. 2019 was bit rough I did a total of 14 weeks lol

 

[Mike1967]

Yes what I meant is it is the default set now in my Perdix in OC TEC mode.

Ah ok, we obviously have different definitions of 'default' lol

 

[Blackcrusader]

Ah ok, we obviously have different definitions of 'default' lol

yes sorry for that confusion. I actually did RTFM several times and again with the new firmware updates. So I made changes that suit me. It's my default setup

 

[mafi]

12l tank with 200 bar start. 150 bar after 25 minutes at 25m.

6.85L / min

Dude, your SAC is impressive :-D

 

[Mike1967]

6.85L / min

Hmm