Practicing deco stops w/o going into deco

[Caversluis]

I would like to practice deco stops without actually going into deco. I have thought of ways to do this, and the thinking is to set my main dive computer to very conservative settings (and thus trigger deco stops), whilst keeping my backup computer at normal settings. I would keep an eye on my backup computer to avoid going into real deco.

I have considered 2 options for a 30m dive on Nitrox 32

1) Settings my Perdix to very conservative gradient factors

2) Set my Perdix to air

Any considerations, inputs or better altenatives?

For context, I have CMAS*, AOW, RD certificates and amongst others Nitrox, Deep, Drysuit, Self reliant specialities. I have logged 190 dives, mostly in cold water. For normal dives, a use a BP/W setup with twinset. For solo dives and deeper/longer dives I also carry a 40cu stage bottle. Eventually, I could see myself moving into technical diving, But for now, I just want to be prepared for a situation where I get (unplanned) into a few minutes of deco.In particular, I want to familiarise myself with my dive computer in “deco mode”. Better to practice and not need it, than not to practice and need it.

 

[Minion_Diver]

The way I practice is that I run tables for a particular dive and then go to my local quarry, stay shallow, and then run that exact profile. That way you can keep you computers setup like you normally would, but would be following the tables that you wrote down.

 

[Boarderguy]

If you're holding a 6.5m safety stop then you're already holding a deco stop. Don't over think it. Most of my deco dives clear on the way up before I hit the first stop and even then I make a safety stop anyways. Unless you're planning some serious deco your stops will be at 6.5m and maybe 3m. On your next dive to 30m just stay down until your NDL expires and watch your perdix during a normal ascent.

Edit: is your perdix set in rec or tec mode? That changes the screen you see, but still performs the same.

 

[rongoodman]

Why bother changing your computer settings? Just practice holding stops every 3 meters or so on the way up. Once you get comfortable with that, you can add some task loading, such as putting up an SMB or switching masks, in order to see if your position changes too much. Your buddy can signal you from time to time to make sure you haven't tuned him out. I don't think I'd recommend practicing gas switches or valve drills without instruction though, in order to avoid developing bad habits.

 

[VikingDives]

I would like to practice deco stops without actually going into deco. I have thought of ways to do this, and the thinking is to set my main dive computer to very conservative settings (and thus trigger deco stops), whilst keeping my backup computer at normal settings. I would keep an eye on my backup computer to avoid going into real deco.

I have considered 2 options for a 30m dive on Nitrox 32

1) Settings my Perdix to very conservative gradient factors

2) Set my Perdix to air

Any considerations, inputs or better altenatives?

For context, I have CMAS*, AOW, RD certificates and amongst others Nitrox, Deep, Drysuit, Self reliant specialities. I have logged 190 dives, mostly in cold water. For normal dives, a use a BP/W setup with twinset. For solo dives and deeper/longer dives I also carry a 40cu stage bottle. Eventually, I could see myself moving into technical diving, But for now, I just want to be prepared for a situation where I get (unplanned) into a few minutes of deco.In particular, I want to familiarise myself with my dive computer in “deco mode”. Better to practice and not need it, than not to practice and need it.

Why not just take tech training?

If you're going to continue on with your plan, I agree with @Minion_Diver, just write out a plan and follow it.

 

[Edward3c]

I would like to practice deco stops without actually going into deco. I have thought of ways to do this, and the thinking is to set my main dive computer to very conservative settings (and thus trigger deco stops), whilst keeping my backup computer at normal settings. I would keep an eye on my backup computer to avoid going into real deco.

I have considered 2 options for a 30m dive on Nitrox 32

1) Settings my Perdix to very conservative gradient factors

2) Set my Perdix to air

Any considerations, inputs or better altenatives?

For context, I have CMAS*, AOW, RD certificates and amongst others Nitrox, Deep, Drysuit, Self reliant specialities. I have logged 190 dives, mostly in cold water. For normal dives, a use a BP/W setup with twinset. For solo dives and deeper/longer dives I also carry a 40cu stage bottle. Eventually, I could see myself moving into technical diving, But for now, I just want to be prepared for a situation where I get (unplanned) into a few minutes of deco.In particular, I want to familiarise myself with my dive computer in “deco mode”. Better to practice and not need it, than not to practice and need it.

Simples. Its called plan the dive then dive the plan. Plan a dive to 33m with mandatory deco stops, but execute the dive to 20m, but follow your plan. When doing mandatory deco you should be running off a slate not relying on your computer. Were you taught how to tables?

Don't forget to do the gas calculations for the planned dive.

 

[steinbil]

I got a bunch of good recommendations in my thread about the same thing.

Here's one exercise I'm excited to try out:

Alternate: Ascent speed 30 sec per m
10m - Shoot Smb, tie it off to a rock
9m - Chill
8m - Flow Check
7m - Valve Drill
6m - Basic 4 and 5
5m - Basic 1, 2 and 3
4m - Modified S-drill
3m - S-Drill, Hover 3 min - Clean up.

 

[DiveLikeAMuppet]

You can easily practice stops on your ascent without deco. Deploy a DSMB from the bottom and pick a depth from which you want to practice stops. 21 meters might be a good one as that's typically where you would switch from your back gas to a deco gas (50 %).

• Start a timer on your computer.
• From the bottom to 21 meters, ascend at 8-10 meters a minute (your computer should beep a little and it will feel like a pretty fast and busy ride up).
• Stop at 21 meters for a minute.
• From 21 meters, on each full minute, spend 30 seconds moving 3 meters up to next stop and 30 seconds on the stop at fixed depth (neutrally buoyant, in trim). Aim at hitting the depth precisely.
• Stop at 6 meters for 3 minutes to run a safety stop.
• Ascend 1 meter a minute from 6 meters to surface (again, 30 seconds to move from e.g. 6 meters to 5 meters, 30 seconds on the stop).

This should put you through the motions if you have never done it before.

 

[gbirch]

All valid suggestions for practicing the mechanics of holding a deco stop, but the original poster also wanted to observe how his computer operates while in deco, which is not a bad thing to understand, so practicing stops achieves objective 1, but to achieve objective 2, Your suggestion of setting a very conservative GF on your computer and following that for your ascent is perfectly viable. This is a great way to observe how SurfGF, GF99, CEIL etc display on your computer in deco mode. I know that most of these you can also observe when not in deco, but taking the time to really understand all of this before you have a real ceiling is an admirable objective.

 

[BlueTrin]

one exercise that is done in GUE fundies and that I found really useful is to finish the dive like this:
- stop at 6m for a few minutes (do your safety stop if you were not in deco for example)

- now you will ascend 1m per 1m, you will signal that you will move up 1m to your buddy (make sure you briefed him that you’ll do these 1m stops)

- every time you ascend, you wait for the whole team to be stable (if everyone is quick wait for the next minute) and indicate you’ll move up 1m again

Repeat this until you are at the surface.

This is quite an useful drill because it teaches you better control, also when you’ll do deco, you lower your surfGF by 7-10% by doing this between 6m and the surface if you take 5-6m to ascend.