Depth Gauge and bottom timer only?

[black1]

Hello all, im new to DIR way of diving and philosophy but very interested in it and have been reading alot about it. I noticed something that i thought i would ask here for those that are DIR divers and that is i see in photos and on the GUE site many divers who use only what looks like a bottom timer and depth gauge, is this correct and if so why. Do you use a computer air/nitrox/gauge or would you go more by simply a gauge setting in such a computer and tables calculations ahead of time. This is just an observation i noticed and could very possibly be completel wrong about this, tahnk you in advance for your clarification.

 

[coldsmoke]

There are several threads in here that discuss this and I would suggest searching for a little more info, but as a general rule there are two reasons why computers are not used.

1. They are not necessary. The calculations are easy enough to do in your head. Plus the bottom timer is more flexible as your diving progresses.
2. You are not trusting something that you might not have a complete understanding of how it gets to the information that it's presenting to you.


Here's a link to some information that you might find informative while you're learning the basics of DIR.
Equipment Configuration | Global Underwater Explorers

Hunter

 

[black1]

Thank you and yes i did find plenty posts on bottom timer and depth gauge, but not a whole lot on the best way to understand using only a bottom timer and depth gauge, can someone direct me to a site that explains using only a depth gauge and bottom timer?

 

[rjack321]

Thank you and yes i did find plenty posts on bottom timer and depth gauge, but not a whole lot on the best way to understand using only a bottom timer and depth gauge, can someone direct me to a site that explains using only a depth gauge and bottom timer?

Lots of good stuff here although some of it's a bit dated.

Recreationally most of us use a memorized table or the "120 rule" and multilevel in our heads. Don't worry about how the deco planning stuff works yet, with <25 dives that's a ways off.

 

[black1]

Perfect thank you this is all i need for now, have a great day.

 

[Mr Carcharodon]

black1,

Rather than using tables, or a computer, it is possible to use a simple set of rules to calculate your decompression obligation based on your bottom time and average depth. The rules only work within a range of depths and times and there are a number of other things to understand like standard gasses, ascent rates and ascent profile etc. It is not a complicated approach but you need to understand it completely before using it or you could hurt yourself. This approach is often called "deco on the fly", or "ratio deco". The basics of this are covered by the introductory classes that GUE and UTD teach. UTD has a class specifically about this: Groups - Unified Team Diving

 

[black1]

Yes thank you, i want to learn this as best as i can and be very proficient at determining such things,may i ask if this class is helpful for recreational 130fsw limit diving as well were there is not a requirement for deco stops (i know all diving is deco diving) but always completing a safety stop at 15ft for 3 min? I have many dives in the 100ft range and yes i did do deco stops in intervals at different depths before the 15ft safety stop but it was my instructor who planned them, i would like to know the reasons why and how to do them myself, is this the best class for me, have you taken this particular class? thanks for all your help.

 

[rjack321]

Yes thank you, i want to learn this as best as i can and be very proficient at determining such things,may i ask if this class is helpful for recreational 130fsw limit diving as well were there is not a requirement for deco stops (i know all diving is deco diving) but always completing a safety stop at 15ft for 3 min? I have many dives in the 100ft range and yes i did do deco stops in intervals at different depths before the 15ft safety stop but it was my instructor who planned them, i would like to know the reasons why and how to do them myself, is this the best class for me, have you taken this particular class? thanks for all your help.

It won't teach you all the skills and judgment needed to do staged decompression dives.

It will improve your theoretical understanding of decompression.

 

[Mr Carcharodon]

Yes thank you, i want to learn this as best as i can and be very proficient at determining such things,may i ask if this class is helpful for recreational 130fsw limit diving as well were there is not a requirement for deco stops (i know all diving is deco diving) but always completing a safety stop at 15ft for 3 min? I have many dives in the 100ft range and yes i did do deco stops in intervals at different depths before the 15ft safety stop but it was my instructor who planned them, i would like to know the reasons why and how to do them myself, is this the best class for me, have you taken this particular class? thanks for all your help.

black1,

Yes ratio deco applies to recreational dives under 130 fsw. Within a recreational context it will require an ascent to half max depth and then stops at 10' intervals to the surface. For 100 fsw dives this is rather different than ascending to 15 fsw and hanging there for 3 minutes. Ratio deco applies some of what has been learned from bubble models to eliminate the inert gas you have absorbed on the dive more quickly than would be the case on a more classical Haldanian ascent. And ratio deco tells you what to do if you run over your NDL. There is no one size fits all decompression approach. So for example it will give you a plan for what to do if you have DCS risk factors like being cold, or being physically stressed, during your dive. The other side of this coin is to have a solid handle on how much gas you need. There are links to gas management on this site.

Incidentally I have not taken the UTD ratio deco course on line so I do not know if this is a good course or not. But I did take RD with Andrew G. and it was a blast. So I expect the on line course is OK. It may be oriented to a tech audience however.

And again do not try to learn everything here. Please do get all the details. Still it is really a simple system, certainly no less safe than blindly following a black box on your wrist.

 

[TSandM]

black1, if you are seriously interested in this approach to diving, I would highly recommend taking either GUE Fundamentals or UTD Essentials. Both will present an organized and rational approach to ascent strategies for recreation range diving. The approach involves keeping careful mental track of your bottom time profile, and deciding on an average depth and a decompression schedule based on that. Most of us, while we were learning to do this, continued to run a computer in computer mode as a crosscheck, until we developed enough confidence in our facility with the calculations to discard the computer. We did not simply jettison it one day.