Need help to master dive tables

[bosshogg357]

Can someone please direct me on where I can find a good explanation of how to use the Padi dive tables. Any help is appreciated. I purchased a computer, but I want to really master the tables. Thanks,
Brad

 

[ScubaFreak]

Hi boss hogg,

Scubatoys.com does a great table teacher. Its free to Scubaboard members, just send them an email via the website, or a private message through this forum.

Good luck, and welcome to the board.

Scubafreak

 

[mixdiver]

The extra book that comes with a new padi ow crew pack is the best place to start. Did you get a new table? Have you started your class?

 

[bosshogg357]

I was certified a very long time ago. I am now trying to re-learn the skills. I downloaded the tables. I just purchased a dive computer and I am trying to put this all together for my next dive. I want to know how use my Gekko for my next dive trip and what I will be needing to look out for.

It looks like the gekko automatically goes into safety stop mode. However, after we have surfaced, I don't know what to ask so that I am safe for the next dive on a two tank dive. I was in Playa last year, and the group all had computers. When we surfaced they were very concerned that we not enter the water until a designated amount of time had passed. I am trying to figure out what they needed to know from the DM and how it applied to the next dive we all were taking. I want to be able to rely on my own knowledge and not the DM, if I can help it.
Any help is greatly appreciated,
Brad

 

[H2Andy]

However, after we have surfaced, I don't know what to ask so
that I am safe for the next dive on a two tank dive.

you have all the information you need in your computer. read your manual,
and figure out how to bring the NDL's for the various depths. the computer
will re-calcualte these automatically every minute.

for example, after ten minutes out of the water, you should be able to access
a screen that tells you your maximum time at various depths. it will look
something like:

20 - 5:40
30 - 4:20
40 - 3:10
50 - 2: 05
60 - 1:10
70 - :30
80 - :14
90 - OO

or something like that. meaning that, for example, at that moment, you could
dive to 60 feet for 1:10

as your surface interval increases, you will see that your bottom times at
those various depths increase as well.

does this make sense?

(also, i would STRONGLY urge you to learn how to completely use your computer
and tables, and understand why and how they do what they do before diving
with them, for your own safety)

 

[Marek K]

I was in Playa last year, and the group all had computers. When we surfaced they were very concerned that we not enter the water until a designated amount of time had passed.

Hi Brad--

Yeah, what H2Andy said... you need to refresh yourself on the tables, and you need to thoroughly study your computer's user's manual.

What those guys last year were doing was, during the surface interval their computers were telling them that, after the first dive, they could now stay at x depth for y minutes... basically scrolling through Table 3, except their computers were updating that information all the time based on how much SI time had gone by. The divers apparently knew what depth they were expecting to dive to, and how long they wanted to stay; they were waiting for their computers to tell them that enough SI time had gone by to do so.

I'm not familiar with the Gekko... does it have any simulation modes? Problem is, with many computers, when you're learning how they work, the only thing you can simulate before you dive is scrolling through the initial NDLs... you won't see how that information actually updates during your SI, what happens on the actual screen when you reach your safety stop depth, and you certainly won't see what happens when it goes into emergency decompression mode (not that there's any excuse for that happening).

How long ago were you initially certified? I had a 13-year break from diving prior to last year, when I sat in on my son's OWD course. Very useful... a lot of stuff had changed -- equipment, procedures... and I wasn't diving with a computer in 1991, either! In fact, I was using the old PADI tables, before the RDP...

I found last year, after studying my computer's manual, that everything that was going on on my computer in the water was pretty obvious... depth, NDL time remaining, nitrogen loading indicator, ascent speed indicator, safety stop information... I just hope I can figure it our if I ever find myself in a *gulp* emergency deco situation.

--Marek

 

[boulderjohn]

It looks like the gekko automatically goes into safety stop mode. However, after we have surfaced, I don't know what to ask so that I am safe for the next dive on a two tank dive.

It will be very difficult for you to mix the tables and the computer. In a multi-level dive, your computer might give you much more time than the tables will allow, and the pressure group that the table gives you will not accurately reflect your actual situation.

H2Andy told you the basic idea. I am not familiar with your particular computer, but maybe I can help you know where to look by describing what I do on my computers.

On my Suunto Cobra, I can press one of the buttons to go into the PLAN mode. I can then scroll through various depths, and it tells me how much bottom time I would have if I started then. Of course, that assumes that I will be at that depth the entire time. If I do a multi-level dive with the planned depth as my maximum, I will get more time than the planner told me.

On my Uwatec Alladin Prime, two clicks of the right button gets me to the Dive Plan function, and it works about the same as the Cobra.

In your manual, look for the word PLAN somewhere. It's actually pretty easy.

 

[bosshogg357]

My Computer is a Suunto Gekko. It does have the plan button as you described. I have not used that function as of yet. My girlfriend got certified last year and she has since misplaced the manual from Padi. I am trying to avoid having to buy it, if possible. I downloaded that shareware program and was using it to reacquaint myself.

I also have the new computer that I am learning to use. I have studied the manual, but I have not yet made it to the plan stage. I am getting used to all the functions as we speak.

By looking at the dive tables I saw that the free program I downloaded gives the 2nd dive in a repetitive dive sequence. I just didn't see how it fitted together with the first dive if I didn't know how long the 2nd dive would be. I assumed I could ask the DM what depth we would be going too. However, I felt that he may be off a little bit and I just wanted to know exactly what I needed to ask him so that I can compute my own bottom time, etc. When that group got very serious about not re-entering the water until a designated time had elapsed, I just didn't know if they knew the bottom time or depth or both or they were averaging etc.

I want to have it down cold for my trip coming up shortly.

As always, any additional help is greatly appreciated.
Brad
P.S. After looking at the program, it asked me on a repetitive dive if I wanted to stay down for 15 minutes at 75 feet then I had to be in Pressure group C. This is where I am stuck now. What is it that I need to know about this? I see where I would follow the table to get what pressure group I need to be in. However, what does this tell me and what table do I look at once I have this informaiton. Do I ask the DM how deep, how much time will be down, etc etc. Or, do I just use my computer while I am down and go up to my safety stop when my computer says and not follow along with the rest of the group? This is where I am at the moment. Thanks for your help.
Brad

 

[bosshogg357]

On my Suunto Cobra, I can press one of the buttons to go into the PLAN mode............If I do a multi-level dive with the planned depth as my maximum, I will get more time than the planner told me.

Ok. So, I see that I don't have simulation mode. It does not appear that I will be able to dive before our trip. When in the boat, prior to our second dive do I ask the DM the following:
1. how deep are we going to be?
2. For how long is this dive planned (our 2nd of the day)

After getting this info, do I then click plan and see how long the computer says I will be allowed to stay at that depth assuming I was to be at that depth the entire time? THen when I don't stay at that depth the entire time, the computer will tell me while underwater how long I have left before I go to safety stop?

Thanks,
Brad

 

[mike_s]

Take the Nitrox course. It spends a lot of time on the tables.