Computer vs tables

[gcbryan]

I agree it's all about thinking regardless of whether you use a computer or table to go along with that thinking.

On a related note...if you dive frequently you will probably develop a fairly consistent dive profile which you will use from dive site to dive site. If you do this you will notice that your average depth will be fairly consistent from dive to dive.

This makes it easy to know what you should be doing underwater and your computer just serves to confirm this.

Most of my dives are to 120 fsw for just a few minutes with a little time at 65 fsw or so and quite a while at 35 fsw and shallower. As long as there is something to see at 120 fsw at a particular site I generally follow this profile. If the site is not that deep or there is nothing to see then perhaps I'll only go down to 60 fsw.

If it's 60 fsw or less there is very little to plan as I can stay 60 minutes even using a square profile (table). If it's deeper I treat it like my standard profile which I know well by now.

The computer, gauge mode or not is just to tell me what I already know.

The argument doesn't really have to be whether to use a computer or not. Just learn enough to test yourself from time to time to see if you come up with the same or more conservative info as the computer.

 

[Pumpkin King]

Huh? Gotta keep track of the nitrogen.

Unless I'm wrong, that's all the basic tables track. I'm using the RDP with the repetitive dive table on the back.

 

[RS]

Hi Stag,

I don't get your ?. Am I missing something??

On repetitive dives residual nitrogen will shorten the NDL time so you can't plan a repetitive dive as 0:00 SI. That's what pressure groups are for. All tables are designed to account for descent and ascent (and surface intervals). You just get the bottom time by timing begin of descent to begin of ascent. But the table recommendations assume you are compressing and decompressing within the limits given on the table.

 

[TSandM]

Gray, you're so right. The vast majority of my diving locally is done at only a few sites, and the profiles are so familiar to me that I could do them without a depth gauge if I had to

The place where it gets more important is with repetitive dive, repetitive day trips. Then you really have to start thinking about what you're doing. Travelling and doing dives outside of your accustomed profiles requires some careful thought, too.

 

[Garrobo]

I'm in the same boat as Mark01. All my diving is two morning dives (sometimes the one o'clock dives if a bunch of wusses cancel because of waves or something), deepest first, half hour between dives and shallow dive last. Sometimes a night dive too if we can get enough adventurous soles. If we're gonna do a second 'deep' dive, nothing over about 100 feet, one hour SI. This scenario worked the first day and all subsequent days. All you need is a memory. The computer is nice because it monitors your ascent, captures your dives for later entry into your log book, tells you when you can fly, what time it is, temp of water and so on. Beats the hell out of messing around with old Navy WWII tables. If computer goes out just remember: Two minute stop at 50 and 30 feet and a 3 minute at 15. Problem solved.

 

[RS]

post deleted

 

[SteveAD]

Hi Stag,

I don't get your ?. Am I missing something??

On repetitive dives residual nitrogen will shorten the NDL time so you can't plan a repetitive dive as 0:00 SI. That's what pressure groups are for. All tables are designed to account for descent and ascent (and surface intervals). You just get the bottom time by timing begin of descent to begin of ascent. But the table recommendations assume you are compressing and decompressing within the limits given on the table.

I'm pretty sure the 0 surface interval being referenced is to use conventional tables to plan multilevel dives, planning the various depths as separate dives with no surface interval. I've played with the theory and got very similar profiles between PADIs Wheel RDP (which is designed for multilevel calcs) and the squre RDP using 0 surface interval.

 

[bperrybap]

Actually, I've been delighted to compare my personal depth averaging to what my gauge comes up with for an average depth for the dive. I've never been more than five feet off. But it takes work to be that CONSCIOUS of your dive. You have to check depth and time every five minutes, and remember what you saw, and keep a running tally. I used my computer as a computer for almost a year after I started DIR diving, before I felt confident enough to put it in gauge mode.

If the GUE/DIR method of tracking NDL is more conservative than the computer,
(which is what I think you said in an earlier post) why put the computer in gauge mode?
Especially when doing NoDECO diving on unfamiliar sites?

Why not keep it enabled and simply ignore the NDL stuff and use it as a backup
to your mental calculations in case you make a mistake?


--- bill

 

[RS]

Oh that makes sense then. I thought he meant repetitive dives. Thx

Is that where you use the BT at depth A to get a pressure group, then use the RNT for depth B to see NDL at that depth?

 

[RS]

If the GUE/DIR method of tracking NDL is more conservative than the computer,
(which is what I think you said in an earlier post) why put the computer in gauge mode?
Especially when doing NoDECO diving on unfamiliar sites?

Why not keep it enabled and simply ignore the NDL stuff and use it as a backup
to your mental calculations in case you make a mistake?


--- bill

I'd guess that most folks do this with the backup computer in their pocket.