Tables question (PADI tables) could apply to all i guess

[Marek K]

I need to be in bed
Ber :lilbunny:

Then go...

to...

bed.

Oh, maybe you did already.

Hope you get better. All four of us in the family just got over a killer two- or three-week-long head cold. Right in the middle of our annual week-long ski trip to Austria. Bummer.

Yes, we all skied anyway. Bummer.

--Marek

 

[Ber Rabbit]

Wish I could, I'm at work now and I have to teach a class tonight. Maybe the scuba will flush this garbage out of my head, if it weren't for my great staff there would be no way I could get through class tonight.
Ber :lilbunny:

 

[amascuba]

But back to N@rco$i$'s (oh, that looks weird) original question...

I think the reason that the (PADI and SSI, anyway) procedures are that "bottom time" starts when your descent starts, and ends when your direct ascent starts, is that it doesn't require beginning students to have to calculate ascent rates in order to figure out when they have to start their ascents.

Otherwise, it would be like the silly guidance to "be back on the boat with 500 psi."

--Marek

SSI does have guidence on ascent rates. SSI states that your ascent rate should be 30 feet a minute. That is buried in the open water book somewhere. I can probably go look is up and give a direct quote from it if needed.

 

[amascuba]

I found an SSI table.
Depth NAUI NDL SSI NDL
40 130 130
50 80 70
60 55 50
70 45 40
80 35 30
90 25 25
100 22 20
110 15 15
120 12 10
130 8 5

OK, not exactly 3 minutes (can't think when I'm sick) but NAUI isn't giving you more dive time than SSI, they just expect you to stop your clock in a different place. I need to be in bed
Ber :lilbunny:

What SSI did was take the Navy NDL tables and make them a little more conservative. I've read exactly what they did to make therir tables somewhere. I think it's in the DiveCon manual.

 

[Ber Rabbit]

NAUI did the same thing

 

[Ber Rabbit]

I have another set of dive tables called the "Michigan Dive Tables" those are the ones I originally learned to dive with.
Ber :lilbunny:

 

[dbg40]

Do any computers work this way? Where you enter a plan, and the computer guides your dive. This would be a sort of electronic slate. How would it handles departures from the plan?
Interesting device.

Can't answer for all computers, but my Prime lets me dive in eather mode. I can enter my dive plan, and have it remind me, or just go in dumb, and let it do the work for me.
If I let the computer do the work, I plan it before hand anyway (depending on the dive) that way there is a backup incase the computer fails.

 

[Marek K]

SSI does have guidence on ascent rates.

Sorry, I was sloppy in what I wrote... the discussion was about when "bottom time" begins, and particularly ends; and Ber pointed out that NAUI defines bottom time as ending when the diver reaches the surface again. By "calculate ascent rates," I meant that this requires a new student to figure out how long it's going to take them to surface, based on depth and (hopefully known and controlled) ascent rate -- then subtract that time-to-ascend from allowable bottom time, so they know when to start their ascent.

Not rocket science, certainly; and a good exercise. But PADI's and SSI's definitions make it simpler -- and are really just other approximations.

And that may help explain the slight differences between the NAUI NDL times, and the slightly-shorter SSI times.

But probably not... PADI's depth-vs.-NDL curve sort of intertwines around the two other agencies'. Which means that NAUI's tables, when taken together with their definition of end of bottom time, make their procedures slightly more conservative.

Yes?

--Marek

 

[amascuba]

Sorry, I was sloppy in what I wrote... the discussion was about when "bottom time" begins, and particularly ends; and Ber pointed out that NAUI defines bottom time as ending when the diver reaches the surface again. By "calculate ascent rates," I meant that this requires a new student to figure out how long it's going to take them to surface, based on depth and (hopefully known and controlled) ascent rate -- then subtract that time-to-ascend from allowable bottom time, so they know when to start their ascent.

Not rocket science, certainly; and a good exercise. But PADI's and SSI's definitions make it simpler -- and are really just other approximations.

And that may help explain the slight differences between the NAUI NDL times, and the slightly-shorter SSI times.

But probably not... PADI's depth-vs.-NDL curve sort of intertwines around the two other agencies'. Which means that NAUI's tables, when taken together with their definition of end of bottom time, make their procedures slightly more conservative.

Yes?

--Marek

ahh. Thanks for the explanation.

 

[Ber Rabbit]

It's like everyone has copyrighted their stuff so every agency works hard to come up with a new way to say the same thing LOL! There are only so many mathematical models available :biggrin:
Ber :lilbunny: