An Experiment

[wedivebc]

You can use the tables this way as a multilevel. I used to teach it to my AOW students. You just have to remember to add your ascent time between levels to the deeper depth so you 10 minutes at 100ft should be 11 minutes if it takes a minute to get to 70ft, make sense?

 

[gcbryan]

I made the original post saying that 25 minutes of deco was indicated. The original scenario was much different than this one. The 25 minutes did seem too much but it was late at night.

I checked my results the next morning and saw that I had made a mistake punching in the numbers and posted to that effect. V-planner did allow that profile. The scenario was close enough that I wouldn't have done it as it involved more "riding the computer".

I've sure your method works or comes pretty close. I do similar things in my head and use a computer just as a check. Whether you use a computer or a table and whether it's "allowed" or not it's still good to understand what's going on.

It's much better (in my opinion) to do your deeper time and move up an atmosphere at least before the next part of your multilevel profile. It's better to spend more time in the shallow segment of that profile after you have been deep.

As I recall the original scenario was more like 90fsw 10, 70fsw 20, 50fsw, 20. It turned out that you could do it. I wouldn't however. I would prefer something more like 100fsw 15,50fsw 5, 30fsw 15 or whatever.

You current scenario is no problem without doing any more than just glancing at it. You have 10 at 100fsw and 10 at 70fsw and all the rest is at 40fsw and shallower. If you can do 20 at 100fsw then of course you can do 10 at 100fsw and 10 at 70fsw and you can stay virtually all day once you get in the 30-40fsw range.

 

[The Chairman]

vpm vs Buhlmann aka mend and bend algorithms....why do you think everyone is so tired when they dive air to the edge of NDL, and feel so much less tired when they switch to nitrox for the same dives

Answer: They're as bent as you can get without going beyond sub-clinical symptoms.

Pyle (deep) stops are the solution for me when I do recreational dives. 3 minutes at half of my depth and a full 5 minutes at my shallow stop keeps the sleepy/dragged through the bushes feeling away, whether I am on air or NitrOx. It's good stuff.

BTW, whenever I have cut my own tables using vPlanner of MVPlan, my Veo 250s follow along really well. I thought I would be locked out, but it was cool.

 

[gcbryan]

Pyle (deep) stops are the solution for me when I do recreational dives. 3 minutes at half of my depth and a full 5 minutes at my shallow stop keeps the sleepy/dragged through the bushes feeling away, whether I am on air or NitrOx. It's good stuff.

BTW, whenever I have cut my own tables using vPlanner of MVPlan, my Veo 250s follow along really well. I thought I would be locked out, but it was cool.

I agree, it's more how you shape your ascent than the fact that you brushed the NDL's that keeps that tired feeling at bay.

 

[iztok]

Now this thread got me to start Suunto Dive Planner and enter some numbers for some potential dive sequence.

I realized that I don't have a clue how to read dive plan at all. Things that I can't remember from my classes (I have PADI) are OTU, CNS, END and probably other stuff.

I don't even know if this was covered in the classes at all. (We did table planning.)

Can someone point me to the right direction to learn about this?

 

[boulderjohn]

Now this thread got me to start Suunto Dive Planner and enter some numbers for some potential dive sequence.

I realized that I don't have a clue how to read dive plan at all. Things that I can't remember from my classes (I have PADI) are OTU, CNS, END and probably other stuff.

I don't even know if this was covered in the classes at all. (We did table planning.)

Can someone point me to the right direction to learn about this?

The things you are talking about are not covered in basic OW classes. They do not relate to normal air diving within recreational limits. .

 

[iztok]

The things you are talking about are not covered in basic OW classes. They do not relate to normal air diving within recreational limits. .

Ah, good 'coz I would be upset if I forgot it so soon!

So for my recreational planning as long as my dive plan doesn't go below the max depth for nitrox mixture and it doesn't say "deco" I should not worry about those other numbers?

 

[boulderjohn]

Ah, good 'coz I would be upset if I forgot it so soon!

So for my recreational planning as long as my dive plan doesn't go below the max depth for nitrox mixture and it doesn't say "deco" I should not worry about those other numbers?

I was talking about basic OW.

If you are nitrox certified, you should know CNS (central nervous system oxygen toxicity). You should know that is a threat if you exceed your MOD (Maximum Operating Depth).

You should also be aware of Oxygen Toxicity Units, but for normal recreational diving, it is not a concern. You would have to be doing a whole lot of diving with high oxygen levels before that became something to worry about. You will probably never come anywhere close unless you get into technical diving and start breathing pure O2.

If you do get into technical diving, you will want to control nitrogen narcosis by using a mixture of gases that includes helium. By limiting the amount of nitrogen in your system, you can dive deeper and keep an Equivalent Narcotic Depth equal to a much shallower dive.

 

[Kern]

In the past, I have only used V-Planner for decompression dives. Not long ago I fed a number of square profiles that would be within NDLs on any dive table into the program. In each one, V-Planner required surprisingly substantial deco stops.

I find that puzzling.

In Haldanian models you are allowing tissue tension to build not just to supper saturation, but past it to critical supersaturation or "M" values, to prevent the formation of bubbles. Bubble models assume you already have free phase gas before this point & attempts to keep these bubbles below some critical volume. The way I see it, the bubble model will not allow the tissue tension to build to the level of an Haldanian model & will require a different shape to the ascent profile. It will therefore be quite conservative in comparison for deeper N/MDL square profile dives but evens out over a multi level profile. (Feel free to correct.)

In other words, if you wan't to go deeper, but stay within N/MDL, make them multi level & if you want to do sub 30 mt square profile dives stick with staged deco.

I do not believe a computer like the X-1 that uses V-Planner is representative of the PDCs that are used by 95% of the divers who use computers (Suunto, Uwatec, Aeris, Oceanic, Sherwood, etc.)

Why not John?

 

[boulderjohn]

I It will therefore be quite conservative in comparison for deeper N/MDL square profile dives but evens out over a multi level profile. (Feel free to correct.)

In other words, if you wan't to go deeper, but stay within N/MDL, make them multi level & if you want to do sub 30 mt square profile dives stick with staged deco.

Originally Posted by boulderjohn View Post
I do not believe a computer like the X-1 that uses V-Planner is representative of the PDCs that are used by 95% of the divers who use computers (Suunto, Uwatec, Aeris, Oceanic, Sherwood, etc.)

Why not John?

My reference was to square profiles, where the difference, as I said before and as you seem to agree, is extreme. More common dive computers do not require extended decompression stops on NDL dives, as V-Planner (and thus the X-1) will.

I don't know about your contention that they even out in multilevel dives. I would have to test it.