Navy Deco Table Question

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Carl_F

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Scuba Instructor
Divemaster
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Location
Seneca, SC
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500 - 999
Working through the TDI Deco Procedures book in preparation for the class at the end of January. A question occurred to me reading the explanation of the deco tables.

For a repetitive dive, deco or NDL, can you use the residual nitrogen group to get the residual nitrogen time and apply that RNT to the subsequent dive? Again, either as a deco dive or NDL dive?

Thanks!!!

Carl
 
uhhh that's how you do dive tables...
residiual nitrogen time-RNT
+ actual dive time-ADT
= total nitrogen time TNT

take that and cross reference to the decompression table and you have your deco times for repetitive diving... If you are up in the Greenville area, there is a buddy of mine up here who is quite well read on deco theory and I'm not half bad either and we'd be more than happy to work with you on any questions you have.
 
Thanks! I suspected as much but didn't want to assume it also applied to the deco tables.

I'm over in Seneca west of Clemson so reasonably close to you. I'll drop a line with other questions as they arise! Most of he others I have at the moment are related specifically to how the instructor plans on conducting the class. (Taking it during a trip to the Caribbean in January ... gotta love warm water!!)
 
Carl

Think about it this way::: you make a first dive and hit ndl. you do a short surface interval and get back 20 minutes.. then you do a second dive for an 40 minutes and end up 20 min past ndl. I am guessing the root of your question was how can you do a repedative dive and not do a deco on the first to get up do the si and then a second dive and then doing all the deco at one time. Its a strange scenereo on the surface but looking deeper into the question its how most divers get into unintended deco requirements. The thought reinforces the idea that the surface interval is to prevent such an event.
The tables just need to know how much nitrogen time you have regardless on how you aquired the obligation.
 
Carl

Think about it this way::: you make a first dive and hit ndl. you do a short surface interval and get back 20 minutes.. then you do a second dive for an 40 minutes and end up 20 min past ndl. I am guessing the root of your question was how can you do a repedative dive and not do a deco on the first to get up do the si and then a second dive and then doing all the deco at one time. Its a strange scenereo on the surface but looking deeper into the question its how most divers get into unintended deco requirements. The thought reinforces the idea that the surface interval is to prevent such an event.
The tables just need to know how much nitrogen time you have regardless on how you aquired the obligation.

Thanks. The question was just trying to validate RNT could be used with deco tables for repetitive dives. I didn't see in the TDI book that specifically discussed it. It makes sense but every assumption I make is a likely error.
 
Honestly I would be surprised if you even use those tables during the course. If I were a betting man, I would bet on the instructor having you use V-planner, I-deco, Baltic Deco Planner or some other technology based deco planner. you can load the software onto your phone and Viola....You have accurate, user adjustable tables that don't require even half a brain to operate properly.
 
In my IANTD advanced Nitrox course we used tables. They are a tool every tecnical diver should be aquainted with
 
They are a tool every tecnical diver should be aquainted with

Software based planners are far superior to hard tables. In fact they are tables, merely custom generated ones that also calculate gas plans.
 
Software based planners are far superior to hard tables. In fact they are tables, merely custom generated ones that also calculate gas plans.

I make my students use both multideco (vplanner but with the option for buhlman/gf) and navy tables. I also make them use the naui technical diver worksheet to learn how to calculate gas needs manually.
 
https://www.shearwater.com/products/teric/
http://cavediveflorida.com/Rum_House.htm

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