Help with Homwork Please

[phxcamera]

Hi All,

Long time mostly silent lurker here. Signed up for the PADI AOW class next month, and have been studying each of the Adventure Dive sections in the book. (Haven't decided which ones to do, so learn 'em all!)

A quick question from the Altitude Diving Section that I answered incorrectly. I'm still scratching my head on this, and would love for someone to help me out on this.

Here is the question:

You wish to dive to an actual depth of 24meters/80feet one hour after arriving from sea level to an altitude of 1382meters / 4532 feet. What is your no decompression limit? What is your no decompression limit if you wait 6 hours before making the dive?

Answers:
a) 11 minutes, 29 minutes
b) 5 minutes, 20 minutes
c) 12 minutes, 20 minutes

Here is my logic for choosing answer C.

Based on altitude tables for theoretical depths, 80 feet @ 4532 feet altitude = 96 feet, on RDP table = 100 feet rounded deep

Based on altitude of 4532 (rounded up to 5000') that makes me a J diver on the RDP tables. After 1 hour SI, I get to C diver pressure group.

A C diver's no deco limit at a theoretical 100ft is 12 minutes on side 2 of the RDP tables.

I agree on the second part of the question. After 6 hours, you are an A diver, and can simply look at the no deco time for the 100' theoretical depth in part 1 of the tables, which is 20 minutes.

The answer in the book is B. It says your no deco time after a 1 hour SI at 4532' is only 5 minutes.

This is working off the tables, not wheel, maybe that's the difference?

Any help would be greatly appreciated. This is a great board!

Thanks!

Chad

 

[Ferrara]

Sorry you didn't get an answer you sooner. Took a quick look at it just now. You are correct in that going from sea level to 5000 ft puts you in group J. you are also correct that after an hour you are in C giving you an adjusted NDL of 12 min. So... you are correct!

Now here is what padi did it wrong! They skipped the 1 hour surface interval. Note: that as a J diver going to 100 ft you have an NDL of 5 min.

Hope it helps

 

[devjr]

I agree.

 

[phxcamera]

Ferrara/Devjr,

Thanks for the clarification. Always easier to figure out any "errors" on the net amongst resident experts than in a deco chamber

Chad