Info Why are tables not taught in OW classes anymore?

[boulderjohn]

I'm glad I was taught the tables, even though most of my dive buddies have computers I still reference the tables, get a planned depth and set my watch on a countdown of that max depth and max time for a plan. Only problem with that is I don't have as much bottom time as I could going to a couple different depths but I could get a laminated tables or something to bring with me if I was concerned about that. Right now I'm more concerned about building my skills better.

In post #63 I gave the specifics of two dives I did in Cozumel in June. I will repeat those dive profiles below. I have two questions for you.

1. How much time would your tables have given you on those two dives?
2. You said, "Only problem with that is I don't have as much bottom time as I could going to a couple different depths but I could get a laminated tables or something to bring with me if I was concerned about that." Could you explain how having laminated tables with you on the dive would change that?

Here are the two dives:
These dives were done using EANx 32. Both were NDL dives--no required decompression.

Dive One
Maximum depth = 126 feet
Total dive time = 83 minutes

Surface Interval = 91 minutes

Dive Two
Maximum DEpth = 88 feet
Total dive time = 92 minutes

 

[JoeTPhilly]

In post #63 I gave the specifics of two dives I did in Cozumel in June. I will repeat those dive profiles below. I have two questions for you.

1. How much time would your tables have given you on those two dives?
2. You said, "Only problem with that is I don't have as much bottom time as I could going to a couple different depths but I could get a laminated tables or something to bring with me if I was concerned about that." Could you explain how having laminated tables with you on the dive would change that?

Here are the two dives:
These dives were done using EANx 32. Both were NDL dives--no required decompression.

Dive One
Maximum depth = 126 feet
Total dive time = 83 minutes

Surface Interval = 91 minutes

Dive Two
Maximum DEpth = 88 feet
Total dive time = 92 minutes

126 feet on 32% nitrox? Houston, we have a problem...

 

[Lorenzoid]

126 feet on 32% nitrox? Houston, we have a problem...

What if the diver spent no more than five seconds at that maximum depth?

 

[boulderjohn]

In post #63 I gave the specifics of two dives I did in Cozumel in June. I will repeat those dive profiles below. I have two questions for you.

1. How much time would your tables have given you on those two dives?
2. You said, "Only problem with that is I don't have as much bottom time as I could going to a couple different depths but I could get a laminated tables or something to bring with me if I was concerned about that." Could you explain how having laminated tables with you on the dive would change that?

Here are the two dives:
These dives were done using EANx 32. Both were NDL dives--no required decompression.

Dive One
Maximum depth = 126 feet
Total dive time = 83 minutes

Surface Interval = 91 minutes

Dive Two
Maximum DEpth = 88 feet
Total dive time = 92 minutes

I decided to help you out and answer my own questions for you, using the PADI EANx 32 tables.

Question One--plan the dives using the tables. Here is what it would ahve been like for you if you had joined us on those dives.

Dive #1 (126 feet)​

Max bottom time is 18 minutes. Of course, you will not spend 18 minutes at that depth, just as we did not. We were only below 110 for about two minutes, but that does not make any difference with tables. It would take you about 3-4 minutes to get to that depth, then another couple minutes to get to our first cruising depth of about 90 feet. At 18 minutes you would be heading to the surface, and it would take you about 3 minutes to get to safety stop depth, so let's give you a total of 25 minutes for the dive. You would then be on the boat for nearly an hour bobbing around on the surface while the rest of us were enjoying a multilevel dive among the corals.​

​

Surface Interval​

We did 91 minutes, but you would get an extra 60 minutes for the time you spent on the boat while the rest of us were diving.​

​

Dive #2 (88 feet)​

If you had gone in right at 91 minutes, your maximum bottom time would have been 27 minutes; with the full 151 minutes, it is 30. Again giving you a 7 minute total ascent, you would have been back on the boat after 37 minutes. You would again have had to spend nearly an hour on the boat while the rest of us were diving.​

​

Question Two--I have no idea how bringing laminated tables would make a difference.

 

[boulderjohn]

126 feet on 32% nitrox? Houston, we have a problem...

And what problem would that be?

That maximum depth is within the standard contingency depth of 130 feet for EANx 32. The PADI EANx 32 tables give 18 minutes at that depth.

In this case, the dive was at the Devil's throat, a coral swim through we entered at 95 feet, plunged to 126, exited, and then began an immediate ascent.

No problem.

 

[Eric Sedletzky]

And what problem would that be?

That maximum depth is within the standard contingency depth of 130 feet for EANx 32. The PADI EANx 32 tables give 18 minutes at that depth.

In this case, the dive was at the Devil's throat, a coral swim through we entered at 95 feet, plunged to 126, exited, and then began an immediate ascent.

No problem.

Looks to me like on 32% at 130’ you are at PP 1.56. At that depth for 2 minutes I don’t see a problem.

 

[Lorenzoid]

Looks to me like on 32% at 130’ you are at PP 1.56. At that depth for 2 minutes I don’t see a problem.

That was my guess, too, as to what @JoeTPhilly was getting at: the possibility of too high a PPO2 causing oxygen toxicity. If that's what he was getting at, perhaps he neglected to consider the time component of ox tox? A mere two minutes at a PPO2 of 1.56 isn't going to cause toxing.

 

[cgblake]

You said, "Only problem with that is I don't have as much bottom time as I could going to a couple different depths but I could get a laminated tables or something to bring with me if I was concerned about that." Could you explain how having laminated tables with you on the dive would change that?

If I had the tables it would be my assumption that as I went up in depth I could spend more time at that depth. Assuming that I was just going up I would be fine and not riding the NDL and staying on the tables. If I went up and down then I would have to check and see whether that would be possible.
For example, on standard air(I don't have a nitrox cert yet) I do a standard OW dive to 60ft. Putting in a contingency because my buoyancy is bad/pretty fish/i made a mistake/something I look at the table for 70ft meaning the maximum amount of time i have is 40 mins. Theoretically(I think) If i went up say to 40ft I could get an extra 40 mins of bottom time. Of course I would run out of air but that is what I meant. If I am wrong please correct me, ill attach a picture to show what I mean.

**This isn't advice this is an assumption, I don't know if this would work properly or not.

 

[rob.mwpropane]

If I had the tables it would be my assumption that as I went up in depth I could spend more time at that depth. Assuming that I was just going up I would be fine and not riding the NDL and staying on the tables. If I went up and down then I would have to check and see whether that would be possible.
For example, on standard air(I don't have a nitrox cert yet) I do a standard OW dive to 60ft. Putting in a contingency because my buoyancy is bad/pretty fish/i made a mistake/something I look at the table for 70ft meaning the maximum amount of time i have is 40 mins. Theoretically(I think) If i went up say to 40ft I could get an extra 40 mins of bottom time. Of course I would run out of air but that is what I meant. If I am wrong please correct me, ill attach a picture to show what I mean.

**This isn't advice this is an assumption, I don't know if this would work properly or not.

Wtf? Why do that to yourself? 1/2 your dive would be spent working out the math, lol.

Get a cheap used computer, plan your dive, and go enjoy those fish!

 

[tursiops]

If I had the tables it would be my assumption that as I went up in depth I could spend more time at that depth. Assuming that I was just going up I would be fine and not riding the NDL and staying on the tables. If I went up and down then I would have to check and see whether that would be possible.
For example, on standard air(I don't have a nitrox cert yet) I do a standard OW dive to 60ft. Putting in a contingency because my buoyancy is bad/pretty fish/i made a mistake/something I look at the table for 70ft meaning the maximum amount of time i have is 40 mins. Theoretically(I think) If i went up say to 40ft I could get an extra 40 mins of bottom time. Of course I would run out of air but that is what I meant. If I am wrong please correct me, ill attach a picture to show what I mean.

**This isn't advice this is an assumption, I don't know if this would work properly or not.

Unfortunately, the tables do not have the information to let you do what you are talking about. Once you've been to (say) 63 ft, then you are committed to the 70 ft NDL (40 mins on an RDP), no matter what depth you dive at above 70 ft during the dive. Yes, if you went up to (say) 40 ft for most of your dive, you would be on-gassing less nitrogen, but the tables do not have the info to tell you anything other than NDL=40 mins, because you went to 63 ft. that's the problem with tables and their assumption of square profiles; if you ar actually diving a multiple levels, you are taking on less nitrogen than assumed by the table, but the table does not tell you how to manage that.