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View Full Version : Logging Dives Exceeding Rec Dive Tables?



JipThePeople
07-25-2007, 21:25
I log every dive I make and tonight while reviewing my log book, I ran across several dives where I had failed to enter a pressure group. My dilemma is that one of my dives was 82 ft for 29 minutes. Referencing the PADI RDP, 90ft has a max no decompression limit of 25 minutes. Since I exceed that time, what am I supposed to record as my pressure group at the end of the dive? Any feedback is greatly appreciated.

picxie
07-26-2007, 04:46
I have this problem as well. I don't worry too much about it, but I do try and fill it in with a best estimate. It's all you can do I think if you are trying to log dives using tables.

cummings66
07-26-2007, 07:36
You don't say if you're using a computer to dive or not. If using tables don't worry about it, your diving is done for the day. Look on the bottom of the chart and you'll see what I mean.
<DIV></DIV>
<DIV>If you're using a computer then log what dives the computer says and forget about the pressure groups. There is usually no way you can do multiple dives with a computer and have it come out usable in table format. So I too do not log pressure groups when I dive, but I do have an idea of what's going on based on the tables before the dive. I use tables to plan the dive, but the computer to time it and keep track of the tissue loading for O2 and N2. In other words if it says I've got 20 minutes at 100 feet then that's the max length of time I'll stay there regardless of what the computer says, but I will come up and dive shallower and do a multi level type dive.</DIV>

FishFood
07-26-2007, 09:38
You don't have to fill out everything in the log book. Just the essnetials. Date, location, max depth, water temp (or I do anyway), and bottom time. Feels like Im forgeting something?

ScubaToys Larry
07-26-2007, 09:54
Other things I tell people to put in... especially if new divers, is what suit they were wearing in what temp, and how much weight did they wear - and did they think it was right. Handy reference for the next time you are diving in those conditions.
<DIV></DIV>
<DIV>Oh yea... and what pretty fish you saw!</DIV>

medic001918
07-26-2007, 10:43
Other things I tell people to put in... especially if new divers, is what suit they were wearing in what temp, and how much weight did they wear - and did they think it was right. Handy reference for the next time you are diving in those conditions.
<DIV></DIV>
<DIV>Oh yea... and what pretty fish you saw!</DIV>
<DIV></DIV>
<DIV>Good advice.</DIV>
<DIV></DIV>
<DIV>Shane</DIV>

Dive-aholic
07-26-2007, 11:22
I log every dive I make and tonight while reviewing my log book, I ran across several dives where I had failed to enter a pressure group. My dilemma is that one of my dives was 82 ft for 29 minutes. Referencing the PADI RDP, 90ft has a max no decompression limit of 25 minutes. Since I exceed that time, what am I supposed to record as my pressure group at the end of the dive? Any feedback is greatly appreciated.
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<DIV></DIV>
<DIV>Dive tables are designed for square profiles - descend to depth, stay at that depth the entire dive, ascend from depth with safety stop at 15'. It's doubtful your dive profile ran that way. Most divers will descend to depth, hang out there for a few minutes, come up to a shallower depth, hang out there for a few minutes, etc. There's a way to figure out a pressure group based on this if you remember the times you were at each depth and what the depths were. But as many others have said, if you're diving a computer, don't worry about it. I can't remember the last time I recorded a pressure group.</DIV>

fire diver
07-26-2007, 12:15
Yep, what they all said. I have never logged a pressure group. Been diving computers from day one. Starting deco diving, that may change, but for all the rec dives so far I haven't.
<DIV></DIV>
<DIV>I actually didn't like any of the production dive logs. I made my own on the computer, so that I can print out how ever many pages I need, as I need them. Plus I can modify the pages as needed. Heres a list of what fields I have on mine (what I felt was important---YMMV)</DIV>
<DIV>dive #</DIV>
<DIV>date</DIV>
<DIV>Location</DIV>
<DIV>time and psi going in</DIV>
<DIV>SI, BT, max depth</DIV>
<DIV>time and psi on exit</DIV>
<DIV>gas mix used, MOD,O2 limits used etc.</DIV>
<DIV>Stop depths and times</DIV>
<DIV>exposure protection, tank used, #of weights</DIV>
<DIV>various water condition data</DIV>
<DIV>a comments block</DIV>
<DIV>a verifacation signature block (that has never been used)</DIV>
<DIV>previous BT, current BT, total BT to date.</DIV>
<DIV></DIV>
<DIV>FD</DIV>

JahJahwarrior
07-26-2007, 12:17
Remember, your log book is YOUR log book. It's not PADI's anymore :) If you don't want to enter something, don't enter it! Heck, not everyone even keeps a log book! (I do, and I keep it religously :) )

The tables don't apply unless you dive a completely square profile. You gear up in the parking lot and poof just appear at your chosen depth, dive until your planned time then poof you appear at your safety stop. Wait there and then poof you appear back in the parking lot or on the boat. Unfortunately, they only designed the rules for the system and never got the whole instant transportation thing working. :) Because you spent some time getting down to depth, some time coming up, etc, a "pressure group" is really very hard to define. It would be much better if we could monitor the amount of nitrogen in our blood with al ittle read out in the navel or something, and enter than int he logbook, tht's useful info. Depending on your mass and many other factors, you may have more or less N2 in your blood than someone else who dove your exact same profile right next to you. But you will both be in the same "pressure group." See how it's not really the best thing? Your computer isn't perfect, because it doesn't know your mass and body fat (different tissues release N2 at different rates) but it improves on the table concept by tracking your dive time and depth much better than a table can, and is automatically conservative, because if you stay horizontal and aren't using hands much, your comptuer should be lower than most of your body mass.

So I sometimes bother with a pressure group, but if I "blew the table" then I don't, and ifI don't hav ea table handy when entering info in the book, I don't. :)

Queen
07-26-2007, 12:31
Remember, your log book is YOUR log book. It's not PADI's anymore :) If you don't want to enter something, don't enter it! Heck, not everyone even keeps a log book! (I do, and I keep it religously :) ) ...



That's me, after a few hundred dives I stopped keeping a log book. It got really redundant so when my log got ruined in a basement flood I just never bother to get a new one.

JahJahwarrior
07-26-2007, 13:45
^The main reason I log dives is for # and time spent underwater :) Other than that, the only reason I have it is if I got bent, maybe it would tell them what Iw as doing underwater. But unless you enter it in right away, it won't help :) (only useful for like, skin bends that you dn't notice until a few hours after the dive.

CompuDude
07-30-2007, 15:29
I log every dive. I note the things that will be helpful to ME down the road.

For me, the most important things in my log are location, depth, water temp and gear used (tank, exposure protection (incl DS undergarments), BC and weight). This lets me know what I used last time, when I return to a site I haven't dove for 6 months: What water temps to expect, how deep I'll be going and if I should dive wet or dry. When I switch among various configurations, I know how much lead to put in my pocket weight belt. If I play with things, and it helps one way or the other I'll note that also.

After the important stuff is logged, I add in fun stuff. Sometimes I want to know who I dove with last time I went to a given spot, so buddy name is important to me (when applicable). Anything unusual, and perhaps a general description of the topography (big kelp forest, sand dive, lots of rocky structure, cool swim-thru at 55', things like that) can be helpful, again, for consulting on a return trip. So can things like "terrible vis, perhaps 3', so avoid at low tide". Or "Huge crevice with lot of lobsters... come back when season opens!"

It all depends on how much variety there is in your diving, and how much you play with gear configurations. If I always dove the same three sites in the same gear setup, I might not be as interested in maintaining a log.

cummings66
07-30-2007, 15:44
The tables don't apply unless you dive a completely square profile. You gear up in the parking lot and poof just appear at your chosen depth, dive until your planned time then poof you appear at your safety stop. Wait there and then poof you appear back in the parking lot or on the boat.

I suspect it was never explained to you how tables work. They are built with an assumption of a standard rate and in fact that rate is printed on the tables, for some anyways. Mine says up to 60 fpm.

You are right that it's not straight up and down, but then it was never meant to be that way.

Tables are not exact in terms of on or off gassing and it does depend in part on how fast you go up or down. But on average it works well. If a person wants more bottom time they either get a computer or buy the wheel and dive multi level dives.

I suppose one other option which I don't grasp yet is how DIR divers do it. They have these generic rules which tell you where to stop and how long, but you get to modify them at whim based on what you feel you did or need. That's the part I don't grasp. They claim it works. I know it does for many. How? I've got no Earthly idea because not one of them can explain to me what the rules are.

Until then I'll either use a computer or the tables.

dmdoss
08-01-2007, 22:55
I guess my computer made me lazy, i dont keep a log book anymore.

thesmoothdome
08-01-2007, 22:59
I guess my computer made me lazy, i dont keep a log book anymore.

Log book? what is this log book you speak of? LOL...just kidding folks. I know I've used that one a few times now. Seriously, now that I have a pc download cable, I just keep them on my pc .

BSea
08-01-2007, 23:07
Remember, your log book is YOUR log book. It's not PADI's anymore :) If you don't want to enter something, don't enter it! Heck, not everyone even keeps a log book! (I do, and I keep it religously :) ) ...



That's me, after a few hundred dives I stopped keeping a log book. It got really redundant so when my log got ruined in a basement flood I just never bother to get a new one.

I started out keeping a basic logbook, then I went for about 15 years without logging a dive. Now I log every dive. I also make notes & drawings of what the dive area was like. I have so many dives from the early years that was nothing more than the basic info. Looking back, I don't even remember some of those dives. So now I go out of my way to note something unique about everydive.

ScubyDoo
08-01-2007, 23:19
Hmmm? Nobody has answered your question thus far. They have danced around it. To answer your question...if you go strictly by the tables, you would have to log an ending pressure group of "Z". According to the tables, you busted your NDL by 4 minutes..which dicates a mandatory 8 min. decompression stop at 15 feet, and a minimum surface interval of 6 hours before your next dive.

Now to agree with everyone else....you probably didnt stay at max depth the entire dive, and thus you probably didnt exceed your NDL at all.

If you dove with a computer that allows you to upload data to your PC, it will likely give you an "average depth". I use the average depth in conjunction with the tables to determine my ending pressure groups.

dmdoss
08-01-2007, 23:26
I guess my computer made me lazy, i dont keep a log book anymore.

Log book? what is this log book you speak of? LOL...just kidding folks. I know I've used that one a few times now. Seriously, now that I have a pc download cable, I just keep them on my pc .


yep, that cable made my life easier.

ScubyDoo
08-01-2007, 23:32
"So what if my mask is on my forehead."

LOL.. If you were one of my students I would scold you. That being said...I see all manner of so called professional divers, marine biologists, etc., on television doing the same thing. I'm often amazed at the poor dive training of supposed experts I see on television.

ScubyDoo
08-01-2007, 23:45
I guess my computer made me lazy, i dont keep a log book anymore.

Log book? what is this log book you speak of? LOL...just kidding folks. I know I've used that one a few times now. Seriously, now that I have a pc download cable, I just keep them on my pc .


yep, that cable made my life easier.

True, dive computers can make you lazy. One purpose of logbooks however is that you can go back and see what weight you were wearing, what suit you were wearing, what you saw, etc. Its more than just recording your dive profile and pressure groups. If you return to dive the same sites regularly (as I do in Cozumel), its nice to be able to review your previous notes so that you can know what to expect and what to look for on a particular site. I log EVERY dive, albeit sometimes after the fact due to the luxury of the dive computer. I keep my written dive log, as well as the dive log generated from my dive computer...which allows me to print out all data associated with the dive.

CompuDude
08-02-2007, 01:31
"So what if my mask is on my forehead."

LOL.. If you were one of my students I would scold you. That being said...I see all manner of so called professional divers, marine biologists, etc., on television doing the same thing. I'm often amazed at the poor dive training of supposed experts I see on television.
Off topic, of course... but I disagree with that little gem of dive training. So do a lot of other people, apparently. I don't do MOF. But everytime I specifically put my mask elsewhere, I groan internally at the absurdity.

*shrug*

ScubyDoo
08-02-2007, 02:07
I know that putting your mask on your forehead is a small detail that most people prefer to overlook and as you consider "absurd". There are many dive details that tend to be micro managed. That being said, is it not true that most divers in distress push their masks to their forehead?? The system is set up so that rescue personnel can easlily identify divers in distress. If everyone shoves their masks to their forehead..it becomes a more difficult proposition.

Queen
08-02-2007, 05:35
"So what if my mask is on my forehead."

LOL.. If you were one of my students I would scold you. That being said...I see all manner of so called professional divers, marine biologists, etc., on television doing the same thing. I'm often amazed at the poor dive training of supposed experts I see on television.
Many of us were trained before it became fashionable to teach "no mask on the forehead". Just because the next generation of divers has chosen to embrace different things doesn't make the previous generation wrong or poorly trained. :icon_rolleyes:

Queen
08-02-2007, 06:10
"So what if my mask is on my forehead."

LOL.. If you were one of my students I would scold you. That being said...I see all manner of so called professional divers, marine biologists, etc., on television doing the same thing. I'm often amazed at the poor dive training of supposed experts I see on television.
Off topic, of course... but I disagree with that little gem of dive training. So do a lot of other people, apparently. I don't do MOF. But everytime I specifically put my mask elsewhere, I groan internally at the absurdity.

*shrug*

So true. Since there are so many people who still MOF routinely I think it's time for the agencies to stop teaching new divers NOT to do it. As has been said so many times, a distressed diver is usually the one splashing about in panic...not the diver with MOF who is calmly floating at the surface.

CompuDude
08-02-2007, 12:24
I know that putting your mask on your forehead is a small detail that most people prefer to overlook and as you consider "absurd". There are many dive details that tend to be micro managed. That being said, is it not true that most divers in distress push their masks to their forehead?? The system is set up so that rescue personnel can easlily identify divers in distress. If everyone shoves their masks to their forehead..it becomes a more difficult proposition.
I was going to go into a long explanation, but there's no sense flogging the dead horse. Queen summed it up.

I'll note that MOF is FAR from the most obvious sign of a diver in distress. It's on minor thing among many, and gets far too much emphasis.

Foo2
08-02-2007, 13:46
F.Y.I. there is a WHOLE MOF thread here (http://forum.scubatoys.com/showthread.php?t=930):smiley2:

TxHockeyGuy
08-02-2007, 14:02
Wait, I thought this was a thread about logging your dives. How did this go to MOF?

http://www.scubaboard.com/images/smilies/deadhorse.gif

plot
08-02-2007, 17:58
my divelog only has a few basic things, date, location, dive length, max depth, temperature, and vis.

doesnt have a place for all the table crap and SAC calcs and whatever else. I'd throw away my logbook if I had to fill all of that out every time

CompuDude
08-02-2007, 18:27
my divelog only has a few basic things, date, location, dive length, max depth, temperature, and vis.

doesnt have a place for all the table crap and SAC calcs and whatever else. I'd throw away my logbook if I had to fill all of that out every time
All that crap is optional, whether there is a place for it or not.

*shrug* My computer logs the hard stuff. I just type in notes, vis, etc.