Queston for PADI instructors

[Sea Squirt]

This has been bugging me for a while, maybe PADI people can shed some light on it.

Why is Multilevel Dive planning not one of the mandatory modules of AOW?

I've just completed AOW, and still am not able to plan a multi-level dive, since it was not one of the specialties I chose. How is this going to be compensated for when I do DMT?

 

[Zept]

I'm not an instructor, but...

Why don't you just do the multilevel module as a one-off speciality dive? Or you could do the whole multilevel specialty (two dives), if it's something you're really interested in.


Zept

 

[The Chairman]

PADI's multi-level diving specialty revolves around the use of their wheel. It is up the student and instructor what areas you want to delve into other than the required. My instructor required that we do a multilevel, but forgot how to use the wheel. Most instructors really fumble with them. I took it upon myself to teach me how to use it. I only used it for the DM test and my NitrOx course (where I re-taught THAT instructor) but I could still deal with it. Get and watch their video... it will simplify it considerably.

Of course, I don't need no stinking tables or wheel with my Cobra by my side!!!

 

[Fishkiller]

:stupid:

but my AERIS 500AI works wonderfully for me


of course here is a question along with the fine one by Sea Squirt outside of the tec divers whose dive profiles are mulitlevel? I record my all my dives as X at Y for Z square my computer figures all the rest and we both agree on the NDL limits that each dive produces..

 

[Drew Sailbum]

A couple reasons come to mind:

1. The PADI Specialty Course is officially Multilevel and Computer Diving. Many divers don't have computers, and not all shops rent them, so equipment could be a problem for many AOW students.

2. The Wheel. Most instructors never saw one until they went through their DM and IDC. Most can't wait to never pick one up again.

 

[Se7en]

Perhaps it's because multi level diving without a computer is impractical to actually calculate, so no-one actually does it?

You can use Tables, just as well as the wheel to calculate multilevel profiles - but to get the most benefit (in terms of extended bottom time) you have to be very granular. EG 12 minutes at 32m;4 minutes at 26m;7 minutes at 19m; 10 minutes at 12m etc. And you still won't get as good a result as you would using a computer.

The issue PADI completely misses (due to the belief in non deco diving... done by flying pigs) is that at 12m, some of your tissues will be off gassing, while some will still be ongassing slowly (yeah I know Buhlman is different, let it slide for the sake fo the argument)- ie it is a deco stop for the origional 32m dive.

A computer should take this into account, tables (or the wheel, which is just another view of the information in the tables) never will.

Try running the figures on a dive day where you do a couple of deepish multilevel dives... and see how quickly you fall off the tables using a square profile, or even a basic multi level...

Fishkiller - I'd be really really really interested in seeing a square profile calculated by you that agrees with what your computer says you did on a dive. I suppose that if you dive bombed to depth, sat still, then ascended at 100% of your computers rate (and that rate mathched the rate used by your tables) then they might match - but I don't believe they ever would for a real dive.

Actually - if you had a real lame computer that calculated your dive based on maximum depth obtained, and dive time (ie mimicing the way you calculate a square profile) it would give the same result... and be completely useless as anything but a bottom timer.

Mike

 

[Fishkiller]

Originally posted by Se7en

Fishkiller - I'd be really really really interested in seeing a square profile calculated by you that agrees with what your computer says you did on a dive. I suppose that if you dive bombed to depth, sat still, then ascended at 100% of your computers rate (and that rate mathched the rate used by your tables) then they might match - but I don't believe they ever would for a real dive.

Mike

I record my all my dives as X at Y for Z square my computer figures all the rest and we both agree on the NDL limits that each dive produces..

I did not say match I said agree, my dives as recorded by my computer have yet to violate the tables NDL

hope that helps

 

[Se7en]

Originally posted by Fishkiller

I did not say match I said agree, my dives as recorded by my computer have yet to violate the tables NDL

Ah - I guess I just didn't think that you could agree without having the figures match...

Actually - how DO you agree if the figures don't match?

Hypothetical dive (actually the 2nd last one I did) was roughly;
100ft for 15 minutes
50 ft for 10 minutes
8 minutes on ascent

Now if I calculate that as a square profile: Oops - I fall off the tables...

As a Multi level using the tables;
100ft for 15 minutes (makes me J from RDP)
50 ft for 10 minutes (makes me N from RDP)
8 minutes on ascent (makes me Q from RDP)

As a Q diver, according to the tables the deepest I can go on my second dive is 70 ft for 6 minutes. Diving on a computer, I got a lot more time than this at deeper depths...
Tables and computer didn't match, nor even vaguely agree.


FWIW: I actually went to about 90 ft, for a total dive time of 40 minutes - diving on a wall for my second dive - and didn't get close to requiring a stop...

I may been unusual in diving on walls often, but almost all the boat diving I do violates the tables...

Mike

 

[UKPhil]

We used the wheel on the deep diver specialty and it was actually a worthwile exercise. The numbers weren't too far off my Vyper (set to conservative mode) and if nothing else, it forced us to PLAN the dive, which is not a bad habit for deeper dives.

Phil

 

[The Chairman]

Work these out...

1st dive...
34% EANx to 98ft (EAD=73ft) for 36minutes. SIT= 1:01

2nd dive...
32% EANx to 85 ft (EAD=68ft) for 33 minutes. SIT=1:39

3rd dive...
Air to 81 ft for 29 minutes

According to the tables, I should be in a DCS coma, but this was allowed by my Cobra. The second dive brought me within a couple of minutes of incuring a deco obligation. EAD is "Equal air depth" and its a way to calculate the specific Nitrogen times when using NitrOx. I was having way too much fun to deal with the wheel... Thank goodness for computers!!!