Logging dives--pressure groups and computers?

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

johntclever

Registered
Messages
26
Reaction score
0
Location
NW Arkansas
# of dives
0 - 24
I purchased a dive computer (Atom 3.1) to help me keep track of the interesting information about my dive (temp, air consumption, dive profile, etc)...but I have a question about pressure groups...

Since the computer calculates calculates my nitrogen absorption rate, surface interval, etc...do I need to log my pressure group from the RDP (the same way I would without a computer)...or is there something different I should be including in that section?

I am fine with dive software but I want to make sure I have a paper log since I'd like to be able to get our Master Diver cert in a couple of years--and will need to be able to 'prove' at least 60 dives.

Thanks!
-John
 
a log doesn't necessarily have to contain beginning or ending pressure groups (or just because its on the page, doesn't mean you need to fill it in).........
 
I recommend that you use your tables to calculate pressure groups for the next few dives. Both for practice and to show yourself how much more dive time your computer allows you over the tables.

Then, just ignore it.

Your computer doesn't use pressure groups, so they are really relevant for computer dives.
 
Thanks so much for your quick replies! Definitely want to keep comfortable with the RDP...just in case I have a failure...
 
Thanks so much for your quick replies! Definitely want to keep comfortable with the RDP...just in case I have a failure...

You need to think this through on different paths:

1. Went to dive, and PDC was not functioning. Plan and execute dive(s) with tables

2. PDC craps on or between dives... What do you do?
 
As rhwestfall was hinting at, if you use tables based on the full dive time at your max depth you may find yourself supposedly exceeding no-decompression limits after a few dives, whereas the reality (which dive computers do their calculations from) is that you are sometimes at a variety of different depths and thus have less nitrogen loading than the max-depth tables would have suggested. So keeping in practice with tables is good for keeping you thinking and planning your dives, but if doing multiple dives per day it will limit you - and if you didn't carefully log dive 1 and then your computer craps out you are lacking the information needed to plan subsequent dives according to tables.

I use an air-integrated computer (Suunto Cobra 3) because I like seeing how my surface air consumption (SAC) changes with experience, water temperature, people trying to spear me, and so on. On dive vacations, I also strap on a Suunto Zoop as a backup that runs the same calculations as the Cobra 3. That way, if one computer craps out the other one has my diving history and I can keep diving within computer limits rather than having to cut dives short or end the dive day due to table limits.

When it comes to logs, after about dive 30 I switched to using MacDive on my laptop, with synchronization to the Dive Log app on my iPhone. That way my log is always in my pocket for anyone to see. However, nobody's ever asked to examine my dive log; usually they just want to know your certifications (and they want to see the C-card). They also usually ask you to write down in their waiver form your most recent dive (or, on California charters, most recent cold water dive), and deepest dive, and since you sign off on the form they assume you're telling the truth.
 
A backup comp sounds like a good idea...I have an atomic 3.1 now so I'll probably need to find one from Oceanic to make sure I have the same tables/calculations.

I think I'll also keep spare batteries in my dry bag (for both the computer and transmitter--just in case I end up at a location and have a low batt situation.

The app sounds like a good idea. I am trying out Dive Log and MacDive on my laptop to figure out which one I like better and then get the full version that connects to the app/cloud.
 
OP -- one bit of information -- at least in "PADI Land" (and since you referenced the RDP, I think I can assume you have a PADI cert) a paper log is not required to show how many dives you may have. I log every dive but haven't done a paper one in years. For some of my certs (instructor level) I have had to show my log and the printouts have been just fine.

In fact, to my belief, an electronic log is far better than a paper one.

Re the RDP and computer. Yup, best bet is to get a backup computer IF you are truly worried about having your computer malfunction while on vacation/dive trip. Switching back and forth between tables (whether written tables or electronic like the eRDPml) and a dive computer just doesn't work very well.
 
I think it best not to calculate the actual pressure groups prior to your dive computer failing. That way if it fails, there is no way to know for sure if the rest of your dive day is done, and you can bask in blissful ignorance until you do the actual calculations:wink:
 
OP -- one bit of information -- at least in "PADI Land" (and since you referenced the RDP, I think I can assume you have a PADI cert) a paper log is not required to show how many dives you may have. I log every dive but haven't done a paper one in years. For some of my certs (instructor level) I have had to show my log and the printouts have been just fine.

In fact, to my belief, an electronic log is far better than a paper one.

Have you used them in interactions with PADI itself? Instructors can do what they want, but I would love to see PADI give specifics on what 'counts' for log books for PADI itself. (I am trying to think of when I ever needed to show a log book to anyone, or logs of any kind, and I am drawing a complete blank.)

Actually I would like to see PADI just stop including those outdated paper log book products in the crew packs, so people would start keeping logs that were actually for their own benefit, instead of being worried about questions like the one in the OP. What does the pressure group matter after the days worth of diving when the log books are being written? At that point, the need for even thinking about pressure groups is long gone. It's because we use the outdated paper log book that the question can even be asked.
 
https://www.shearwater.com/products/swift/

Back
Top Bottom