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

[boulderjohn]

We’ve had this discussion many times in the past.
The only thing I can add that is if you decide you want to use a completely analog system with tables to back up your computer then you will need to run the tables along side your computer from the start, so that in the event your computer fails you will be able to calculate repetitive dives using pressure groups. You can’t just decide to start using tables on your next dive after a computer failure without having some clue about accumulated nitrogen load, and if your computer fails without you jotting something down on paper before hand you won’t have that.
And good luck trying to get the two systems to jive. The computer is very good at milking every drop of bottom time out of your NDL, where a table is not.

I don't think there has been any talk in this thread about continuing to dive using tables. For the people advocating having a redundant depth gauge, I don't think I have seen any reason stated as to why it is needed. I have assumed the diver will just end the dive, not revert to tables, which, as you suggest, is borderline impossible in most cases.

 

[Eric Sedletzky]

I don't think there has been any talk in this thread about continuing to dive using tables. For the people advocating having a redundant depth gauge, I don't think I have seen any reason stated as to why it is needed. I have assumed the diver will just end the dive, not revert to tables, which, as you suggest, is borderline impossible in most cases.

I’m sorry, I thought I saw something posted about it, maybe not, my bad.

We’re evacuated right now and the fire came down super close to our neighborhood and I’m a little out of it from no sleep and stress.
I’m just trying to pass some time.

 

[Hoag]

View attachment 615106
I’m sorry, I thought I saw something posted about it, maybe not, my bad.

We’re evacuated right now and the fire came down super close to our neighborhood and I’m a little out of it from no sleep and stress.
I’m just trying to pass some time.

Stay safe.

 

[halocline]

Wow Eric that looks really bad. I hope you stay safe and don't lose your stuff!

 

[Eric Sedletzky]

Wow Eric that looks really bad. I hope you stay safe and don't lose your stuff!

We’re fine.

Back to the thread:
If you want redundancy then get three identical computers. Always carry two on every dive and have one as a spare so that if and when one craps out you will still have two on the next dive. If another one craps out, I don’t know what to tell you other than dive with the last remaining one and if that one craps out then you are benched. Seems like a lot of computers crapping out though to me.

 

[Bigbella]

The only thing I can add that is if you decide you want to use a completely analog system with tables to back up your computer then you will need to run the tables along side your computer from the start, so that in the event your computer fails you will be able to calculate repetitive dives using pressure groups. You can’t just decide to start using tables on your next dive after a computer failure without having some clue about accumulated nitrogen load, and if your computer fails without you jotting something down on paper before hand you won’t have that.

No, not at all.

Provided that you knew the depth and elapsed time, before said computer failure -- say with a handy-dandy analogue gauge backup and a dive watch -- you could easily approximate the placement on the Surface Interval Time Table and the Repetitive Dive Timetable, you would fall under, with conventional tables.

Perhaps go more conservatively; a dirt simple process, even for public school.

This happened many times over the years and was quite commonplace when dive computers first hit the market. Oceanic, among others, back then, often leaked like a sieve. They replaced an old Datamax-Pro -- think brick attached to an HP hose -- three times, back in the early nineties, before I finally jumped ship.

My old, yellow, crispy plastic NAUI tables actually granted me more time at, say, 30 meters (22 minutes on a first dive) than did my old Suunto Solution, which granted a good five minutes less . . .

 

[CycleCat]

... if you decide you want to use a completely analog system with tables to back up your computer then you will need to run the tables along side your computer from the start, so that in the event your computer fails you will be able to calculate repetitive dives using pressure groups. You can’t just decide to start using tables on your next dive after a computer failure without having some clue about accumulated nitrogen load, and if your computer fails without you jotting something down on paper before hand you won’t have that.
And good luck trying to get the two systems to jive. The computer is very good at milking every drop of bottom time out of your NDL, where a table is not.

As my instructor repeated several times "Plan your dive and dive your plan." I will have referred to my dive chart and know from planned depth what my max time is. I have a dive watch and plan to set it when I enter the water. As long as I stick to my plan, even if my computer conks out I can still dive, and take a second dive, if I have a depth gauge and adhere to planned bottom time. I might get less bottom time but my day will not be ruined. Just like the old timers did it.

 

[Eric Sedletzky]

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. Most people look at their screens and just fly the computer until their NDL comes up and they end their dive. Basically, they just do what their computer tells them. If people are pushing the NDL’s right up to the Max and even touching into light deco I think this gets even more critical. Ongassing is not linear, it increases exponentially every minute that goes by past NDL’s, and worse at greater depths.
In this day and age I think it’s irresponsible to advise such practices given the heavy reliance on, and in some cases the abuse of computers.

 

[boulderjohn]

These last comments assume that the diver did not do a multi-level dive on the first dive. On many and perhaps most multi-level dives, the diver will exceed the maximum time for a dive at the maximum depth and thus make it impossible to compute using a table.

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.

 

[Jcp2]

View attachment 615106
I’m sorry, I thought I saw something posted about it, maybe not, my bad.

We’re evacuated right now and the fire came down super close to our neighborhood and I’m a little out of it from no sleep and stress.
I’m just trying to pass some time.

Hope your house is okay. We have friends evacuated out of Skyhawk because the street behind them higher in the neighborhood had houses on fire.