How important is a depth gauge as part of a reg set?

[boulderjohn]

I was about to tell a story from nearly a quarter century ago, and just for grins I got out my very first log book for accurate information. I had been OW certified earlier in the year and then taken a trip to Cozumel, where I immediately did the AOW certification. For the deep dive in that class, they loaned me a computer. For the rest of the trip, I planned to use my tables. On my first dive after the AOW certification, on the Santa Rosa wall, the DM led our group to 90 feet maximum depth, using air, after which we gradually got shallower. We surfaced with a total time of 38 minutes.

As we sat on the boat for our surface interval, I whipped out my tables and started to do my calculations to prepare for the next dive. When I saw that we had exceeded maximum time by about 40%, I was perplexed. I had no idea what to do. I looked up and saw that the other divers on the boat were watching me with amusement. One of them pointed to my tables and said, "It makes a reasonably good Frisbee."

I bought my first computer immediately after that trip. That incident remains the only time in my life I have seen someone try to use tables outside of training.

 

[Bigbella]

I have trouble believing that most people in this computer age will/would keep mental track of accurate depth and time well enough to transfer it over to a table system and not miss a beat.

That may be partially true, for the intellectually lazy; but any knowledge of what to do, once "the lights go out" is potentially valuable -- and quite common, not too long ago.I was shocked that I had to show an adult male how to operate a dirt-simple camping stove (his damn thing), during one of the NorCal PG&E outages. Some time ago, an idiot tried to steal my five-speed truck, near Potrero Hill in San Francisco, not far from the projects. I arrived on site, to see him incapable of leaving my parking spot; kept killing the engine; just couldn't do stick.

Ran until the cops nabbed him, a block or two away (he survived). No skills; everyone laughed . . .

 

[CycleCat]

I have trouble believing that most people in this computer age will/would keep mental track of accurate depth and time well enough to transfer it over to a table system and not miss a beat.

I don't have a cell phone. I have never had a cell phone. I can do this!

I'll dive the computer, but if it craps out, I'll immediately operate as if my entire dive was at my deepest level and adjust accordingly.

 

[Eric Sedletzky]

I don't have a cell phone. I have never had a cell phone. I can do this!

I'll dive the computer, but if it craps out, I'll immediately operate as if my entire dive was at my deepest level and adjust accordingly.

How many minutes did you spend at your deepest level? And how many minutes did you spend at all the other levels, because those times will take time away from your deepest level. Do you remember all these depths accurately? Are you a mathematical genius that knows the proper formula to calculate how all those different depths and how they add up?
What do you think DAN would tell you, or any other hyperbaric professional?

 

[boulderjohn]

I just opened my log book and see that my first dive of the day on 5/8/18 in the German Channel in Palau was to a maximum depth of 92 feet for 67 minutes run time using EANx 32. My second dive that day came about an hour later, and it was to 59 feet. Use any table you want and tell me my maximum bottom time for that dive.

Please -- use your EAN-32 table (I don't have one on hand). Plot your first dive depth, rounding up to 70 minutes. Determine your service interval time table. Follow your "hour" interval to the repetitive dive timetable (Table Two); find your letter grouping (Table Three). Check the value for 60 feet, for the time allotment. It's as big as life . . .

Thanks for the instructions--after teaching tables to hundreds of students, I have the system down, but I will follow your instructions step by step.

Plot your first dive depth, rounding up to 70 minutes. I am not sure what you mean, because I don't know how to round depth to minutes. I will use normal table procedures and round the depth (92 feet) to 100 feet.

You left out the second step, which is figuring your pressure group: Well, I have a problem. On the EANx 32 tables, my maximum time at 100 feet is 30 minutes, but I was down for 70. That means I am not on the table any more. I have exceeded my maximum time by more than 100%.

You left out the next step, which is what to do after you have exceeded NDL by more than 5 minutes: According to the tables, I should have done a 15 minute emergency decompression stop and then stayed out of the water for at least 24 hours. Since I didn't do the 15-minute stop, the normal procedure is to go on oxygen and be monitored for signs of DCS.

Do you have any more instructions for me. I am a little confused as to what to do. I hate to seem so dense, but I really don't know how to do it with those steps missing.

 

[Bigbella]

Thanks for the instructions--after teaching tables to hundreds of students, I have the system down, but I will follow your instructions step by step.

Like I said, I didn't have a EAN-32 table on hand; was going from apparently faulty memory; and mis-typed some crap on my little phone. Only had an air table in my bag.

Mea culpa . . .

 

[boulderjohn]

Like I said, I didn't have a EAN-32 table on hand; was going from apparently faulty memory; and mis-typed some crap on my little phone. Only had an air table in my bag.

Mea culpa . . .

So, how do I plot the next dive if the tables give me a maximum time of 30 minutes and I spent 69?

 

[Eric Sedletzky]

So, how do I plot the next dive if the tables give me a maximum time of 30 minutes and I spent 69?

My best guess is we’ll have to hear once again how to tweak tables to “depth average” - just like a computer!

 

[Bigbella]

So, how do I plot the next dive if the tables give me a maximum time of 30 minutes and I spent 69?

Looks like you're going to sit one out and go snorkeling, heh, heh, heh (which we did with folks who intentionally to unintentionally violated their dive computers or tables, years ago . . .

 

[boulderjohn]

Looks like you're going to sit one out and go snorkeling, heh, heh, heh (which we did with folks who intentionally to unintentionally violated their dive computers, years ago . . .

In other words, you are saying that if you do a multi-level dive and, as a normal result, exceed maximum time on tables, you cannot use the tables to plot a second dive.