Logging multilevel dives with tables

[BoltSnap]

You are absolutely free to choose whichever way you want to live/dive. I have been diving for about 35 years now and I do my best to choose what would and what wouldn't make life easier and more fun for me.

Freedom of choice is great!

 

[Paladin]

Freedom of choice is great!

I agree.

The point I was trying to make is that multilevel dives can most certainly be planned using the tables in the event that one's computer decides to crap out, as anything electronic is prone to do from time to time.

True, a multilevel dive calculated using tables will be more conservative, but you won't be losing much time, especially on a single tank dive. Further, by using the information from a day's previous dives to find one's current pressure group, one can easily switch from a computer to the tables, to determine NDLs, for further dives using the tables should one's computer fail.

I have a computer and use it for its convenience. But I also use the tables. I track each dive using the tables so that I know my pressure group (on the tables) at the end of each dive. Should my computer fail, I'm ready for the switch to "old school" in a heartbeat. Having planned my dive using the tables, if my computer should fail during the dive, I can switch to my depth gauge and watch and continue the dive.

For me, the switch from computer to tables is easy and can be done with very little thought or effort. I do realize, however, that the tables are not being taught the way they were when I learned to dive back in 1965 (I was trained by an ex-Navy diver) and that most divers today are taught to rely more heavily on technology to make things easier. So, for them, giving up on the remainder of a day's diving because of computer failure makes sense. For me, a computer is merely a convenience, not a necessity. I can live with it or without it. True, I might lose a few minutes of bottom time on a multilevel dive plan using tables vs. a computer, but that's no big deal. I have plenty of tanks and plenty of time.

An example of a multilevel dive using PADI tables:

90 feet, 10 minutes.
70 feet, 10 minutes.
40 feet, 20 minutes.

Total bottom time: 40 minutes.

Final Pressure Group: P.

This is well within total NDL and leaves more time at 40 ft. if desired and air supply allows.

Since I frequently resort to my "old school" habits, if you ever come to the East Coast of the US to dive, one of those guys you may run into diving a double hose regulator, no BC, no SPG and no computer just might be me. Don't forget to wave!

Paladin

 

[Blackwood]

I have a computer and use it for its convenience. But I also use the tables. I track each dive using the tables so that I know my pressure group (on the tables) at the end of each dive. Should my computer fail, I'm ready for the switch to "old school" in a heartbeat. Having planned my dive using the tables, if my computer should fail during the dive, I can switch to my depth gauge and watch and continue the dive.

To be fair, it doesn't seem to me that you're switching from a computer to tables. Seems that you're diving planned table dives and using a computer to monitor depth and time. In my mind, those are two different things.

Unless I'm reading too much into that bolded bit and you're just running your actual profile with 0 SIT through the table after each dive.

I'd call that profile 60 feet for 40 minutes which gives me the same pressure group on the PADI table as your method. Ever thought about using average depth instead of stacked 0 SIT square dives?

 

[redacted]

CT Sean,

I am following NAUI's recommendations on SIT less than 10 minutes.

40Fathoms,

If your computer craps out, you sit out for at least 24 hours (or whatever you computer manual says that you have to do). You really can't go back and forth between tables (or Letter Groups) and computers. If you are not comfortable with that still , you should buy a second computer as a backup. What you are trying to do is not reliable, not efficient and highly error prone.

Please note that I am speaking from a "recreational" diving point of view.

Again, get a computer or two. They are dirt cheap these days. Spend your precious time U/W enjoying your dive and still be safer.

24 hours is a pretty stock answer that does a good job of covering the manufacturer's and trainer's ass but leaves the diver unnecessarily dry. You, of course, are welcome to follow and teach that rule. I'd rather use my head a little bit and maybe encroach on a gray area than unnecessarily miss dives.

 

[BoltSnap]

In all of my years of diving I have seen a person diving with a double hose regulator in OW only once. This happened in the late 80's in Rhode Island. This person had no BC, no gauges, J-Valve and shark skin suit!!!Could that have been you??

BTW, most of my diving has been in the NE US!! Diving in New England is the best!!!

 

[Paladin]

I recently spent a week on a dive trip with a bunch of other divers. There, naturally, we discussed a lot diving. One of the topics of discussion was logging multilevel dives and figuring out your profile and pressure group in appropriate tables (PADI, NAUI, you pick).

Since PADI apparently has more or less given up on The Wheel, one diver there suggested that you could log your multilevel dives by treating them as separate dives without surface intervals, e.g.:

A dive goes to 20 meters for 10 minutes.
Then ascends to 15 meters for 10 minutes.
Then ascends to 10 meters for 10 minutes.
Then goes to safety stop and surfaces.

This could be then be logged as one dive to 20 meters for 10 minutes, followed by a dive (with no surface interval) to 15 meters for 10 meters, followed by a final dive (with no surface interval) to 10 meters for 10 minutes. Then you have your final pressure group.

Is this a viable option? I've seen discussions on this around Scubaboard, but haven't been able to find a real conclusion to it.

And I know that there are many of you out there who would just say "stuff the tables, dive with computer only", but I'm old school, as are many of my dive buddies, and we prefer logging our dives and figuring them out using the tables. So while I respect your opinion on tables vs. computers, that isn't the discussion I'm looking for.

It is a viable method and was once used as a matter of course.

PADI tables:

60 ft, 10 minutes. Pressure Group B.
45 ft, 10 minutes. Pressure Group F.
30 ft, 10 minutes. Pressure Group I.

Return to Pressure Group A after 2 hour surface interval.

Hope this helps.

 

[BoltSnap]

awap,

You are right, 24 hours is somewhat a "stock" answer but it meets training organizations' recommendations and most computer manufacturers' recommendations as well. The best place for the answer is in the computer's manual as I have said in my post.

I am not sure of how you can make an informed decision otherwise by not following "industry" or computer manufacturer recommendations. I look at it this way, I'd rather stay dry for 24 hours (or even longer) than suffer DCS. This is not something to toy with or take lightly. Again, if diving is that important and staying wet is crucial, why not use two dive computers?? I do (sometimes I have 3 dive computers on me U/W).

 

[Blackwood]

PADI tables:

60 ft, 10 minutes. Pressure Group B.
45 ft, 10 minutes. Pressure Group F.
30 ft, 10 minutes. Pressure Group I.

Same. I'd call that 50 feet for 30 minutes, = I on the PADI table.

 

[Paladin]

In all of my years of diving I have seen a person diving with a double hose regulator in OW only once. This happened in the late 80's in Rhode Island. This person had no BC, no gauges, J-Valve and shark skin suit!!!Could that have been you??

BTW, most of my diving has been in the NE US!! Diving in New England is the best!!!

LOL No, but it could've been any one of a growing number of vintage equipment divers that hang around the board. I've never been diving that far north, but I've got a couple of friends up there that have invited me to dive with them. I may take them up on the invitation someday in the not too distant future.

Why don't you check out the Vintage Equipment Divers forum here on SB. You might be surprised at just how many of us there are.

 

[BoltSnap]

F.Y.I. My instructor who is still alive and is in his 80's is still diving and using a dive computer, BCD, drysuit but insists on using his old Nikon IV and really old round high volume mask. He claims that his nose is so big that only that mask would fit without causing him pain.