Question on Deco for dive

[Dominantly]

So I was just wanting to pick your guy brains about a situation I had today.

I'll try to keep it short and simple. Went out with 3 other people (1 being an instructor). They were doing their deep dive to around 100', I was staying above them in visual range (60' vis). There was a small current that I was fighting so I began to get a little tired. One student (after their tasks) takes off along the bottom with the others following, I stay above about 20-30 ft but just cant keep up and get tired. I then get a bit nervous (from being winded) and begin to peel up to shallow water I watch my gauge and try to stay with the ascent bars (Gekko), I see the ceiling and dump air to try and stay there (I think I went to about 13') and then dropped down a bit once I was neutral and caught my breath/relaxed. They come up and I head over to do our stop together. we did the 3 mins and maybe a bit more as it would go back to 1, or 2 once we came up a bit (I think went dipped down and then came back to the ceiling). Then we surfaced and swam back slowly ( I had a calf cramp from my exercise).

Recap:
Max depth for me was 93' and I only dipped down that far for a brief period.
Total dive time was 19min, with a minimum of a 2-3 min decent, and a stop for at least 4 mins.
So maybe 12 mins below 60'.


My question is if I did go up to around 13' and then back down to below 15', is that harmful? Does the short time at depth affect the severity of not stopping at 15' exactly?
Any info would be appreciated.
Thank you for your time

 

[ucfdiver]

This short of a dive really falls into the "it doesn't matter" range. A 2ft fluctuation in a deco schedule isn't really a big deal IMO.

 

[Kevrumbo]

Not a problem overshooting by that small amount with a proper slow ascent rate . . .I'd be worried if I overshot while the computer was showing full ascent bars --or worse, a "rapid ascent" warning-- within that last 9m/30' to the deco stop and the surface. . .

 

[Dominantly]

Thank you for the responses.

 

[MauiScubaSteve]

So I was just wanting to pick your guy brains about a situation I had today.

I'll try to keep it short and simple. Went out with 3 other people (1 being an instructor). They were doing their deep dive to around 100', I was staying above them in visual range (60' vis). There was a small current that I was fighting so I began to get a little tired. One student (after their tasks) takes off along the bottom with the others following, I stay above about 20-30 ft but just cant keep up and get tired. I then get a bit nervous (from being winded) and begin to peel up to shallow water I watch my gauge and try to stay with the ascent bars (Gekko), I see the ceiling and dump air to try and stay there (I think I went to about 13') and then dropped down a bit once I was neutral and caught my breath/relaxed. They come up and I head over to do our stop together. we did the 3 mins and maybe a bit more as it would go back to 1, or 2 once we came up a bit (I think went dipped down and then came back to the ceiling). Then we surfaced and swam back slowly ( I had a calf cramp from my exercise).

Recap:
Max depth for me was 93' and I only dipped down that far for a brief period.
Total dive time was 19min, with a minimum of a 2-3 min decent, and a stop for at least 4 mins.
So maybe 12 mins below 60'.


My question is if I did go up to around 13' and then back down to below 15', is that harmful? Does the short time at depth affect the severity of not stopping at 15' exactly?
Any info would be appreciated.
Thank you for your time

So I was just wanting to bump this thread for a few questions and thoughts;

Who was your buddy? Is "visual range" in 60' vis how you were trained to buddy dive? Did you signal to your buddy that you would be surfacing early, alone?

Was this not the first dive of the day? If it was the first dive of the day, the PADI RDP tables I have handy show 20 minutes for max time on a 100' max depth dive (93'), so it would not have been considered a deco dive by tables.

How different is the Gekko from my Vyper? If I am within NDL's, I can end up with a Mandatory Safety Stop instead of a Recommended Safety Stop, if I violate the ascent rate. That usually would manifest itself as at least a 4 minute stop, as the Mandatory Stop time always includes the Recommended Stop time. "The total length of the Mandatory Safety Stop time depends on the seriousness of the ascent rate violation."

That last quote is from my manual. The manual seems to indicate that 10 m/min is acceptable, even short periods reaching 12 m/min are not penalized, but faster than 12 m/min or continuously above 10 m/min are violations. Those numbers are accompanied by 33 ft and 39 ft respectively, in parens.

For a Mandatory Stop due to ascent rate violation, the "Ceiling" is 3 m (10'), with a "Floor" of 6 m (20').

"If you let your No Deco Time become 0, the No Deco Time on your computer will be replaced by an ASC Time notation and the Max Depth will be replaced by a Ceiling notation."

"Rather than require you to make stops at fixed depths, the dive computer lets you decompress within a range of depths (Continuous Decompression)."

ASC Time is the minimum amount of time needed to reach the surface in a decompression dive, and includes all of the following;

-time needed to ascend to ceiling at 33'/min.
-time needed at ceiling
-time needed at Mandatory Stop (if needed).
-time of recommended safety stop.
-time needed to reach the surface after ceiling and safety stop requirements have been removed.

The Ceiling Zone is the optimal decompression stop zone, and is defined as between the minimum ceiling and 1.8 m (6') below the minimum ceiling (10' - 16').

A final question is, why exactly did you need to "catch your breath/relax" after you got neutral at the Safety Stop?

I really think this post could have easily been in the Beginning Divers forum, probably belongs in Basic Scuba Discussions, would only be in Advanced Diving Discussions using PADI's definition of advanced and definitely does not belong in Technical Diving.

 

[Mr Carcharodon]

Depth and time are the two main things to keep track of. Depth variation of a few feet makes little difference. I'd suggest pausing at 30 and 20 feet to slow you down which shoud help with the overshoots. But remember you were well within Ndl so you could have skipped the stop. Be well, have fun diving.

 

[TSandM]

Almost no one can hold a stop absolutely exactly. Most of us will vary up and down a foot or two. Nothing in decompression theory is precise enough to make that kind of variation significant. Rick Murchison puts it best: Decompression theory is measuring with a micrometer, marking with chalk, and cutting with an axe.

GUE, whose standards are as high as anybody's, permits a 3' total deviation in depth for a midwater stop for their technical divers.

If you were stressed, nearly blew a stop, and managed to keep your total depth fluctuation to 2', you are doing much better than I could, even a couple of years ago.

 

[Dominantly]

Thank you all for taking the time to comment.

halemano- This was the very first dive of the day. Quite a few things went wrong with the buddy portion, and I now have a new program because of it. There were 4 of us, with no buddies specifically layed out prior to. When I dive, I am on my buddy very tightly, but the other divers in the group tend to be a bit more loose, and not as "aware". After the two new divers took off (the 3rd not new diver following) I was caught by surprise as I Assumed we would be regrouping and heading to a shallow reef area vs staying in the deep area with just sand. After them resting and my poor choice of kicking above them (To video their training) vs resting myself, I got a little winded. So when they took off I was tired and tried to follow for a second, when I got a bit dizzy. I had some deciding to do very quickly. In my head the options went like this:
Kick swiftly after them at depth and see where the dizzy leads me
Stop and rest while they haul off at depth, hoping they look back to notice fairly quickly
Or begin a slow banana peel up from them, staying on their bubbles, to an area I felt more comfortable being solo (closer to the surface). I also knew that if they looked back and didn't see me, they would realize something wasn't normal and would start their ascent as well.
So I had alot on my mind, watching them, watching ascent rate on computer and depth, and controlling breathing. The water clarity was so good, I could see them below when I was at 30 feet and they would have been around 90.
As for the final question, I was actually catching my breath and relaxing on the peel up, by the time I was at 30 feet I was controlled (minus a superbly dry throat), after a min there I was at 100%.


I'm back in the gym now, gotta make sure that cardio is top notch, if for nothing more then surface swims. :cross: