Backup/redundant gauges

[TartanFrog]

I have the basic dive equipment including an air integrated console computer, back inflate BCD with integrated weights and all the other goodies to get me under the water. I won't list the brands here because that is not really important to the conversation, well at least I don't think they are.

I've been thinking about adding redundant guages but am trying to figure out what to get. I can see the need for Backup/redundant guages like the SPG, depth guage and a bottom timing device. I've spoken with lots of divers and the instructors at my LDS regarding backup/redundant equipment needs and so far everyone has differing opinions and rationale.

I've looked at getting simple SPG and depth guages and using my watch chrono as the backups. So I guess the questions I want to ask are...

What redundant guages, etc. are recommended/necessary for recreational diving?

Given that my primary guages are an air integrated console, which style of guages are recommended?

I know a lot of this will come down to personal preference, but I am trying to get a feel for what other divers do. How they deal with it.

Somehow I get this picture of a guy on the streets of a large city that slides up his sleeve and he is wearing lots of watches.

 

[CAVDVR93538]

In my opinion, the "attached" integrated computers aren't as prone to losing their ability to provide information as the wrist/transmitter type. Either case the redundant (extra just in case) gauge would be an SPG. Usually one would abort a dive when there was an equipment failure, so knowing the amount of remaining air in your tank would be helpful so you know that you are not ready to run out on your way up.

 

[Elvistheking]

I don't get this, just about every tech diver makes do with a single SPG, and 2 wrist mounted depth/timing devices, so if that is good enough for someone doing massively more complicated/dangerous dives, why do you need more than that for a rec dive? Why add more complexity, more points of failure, more cost and more effort (from dragging all these extra dangles through the water)?

 

[Culcuhain]

I have my air integrated Computer and a Citizen Hyper Aqualand dive watch. The watch shows depth and time. If your computer goes out, you know your depth and time... If you know your SAC rate, you should know about how much air you have left... plus how much air (PSI) do you use between glances at your SPG? USe those figures and you should be able to have a safe approximation of the air you have left. I would abort my dive, more than likely, but depending on the dive (ie 20 feet clear visibility shore dive and it dies in the first 5 minutes... opposed to 60 feet and been down 35 minutes...). It works for me... Plus I know my buddy's (wifes) SAC rate and I can compare her readout and have an Idea where I am at.

 

[D_B]

A low cost dive computer, or a dive watch, one that shows depth and time under water makes a good backup .. you could use just time and your depth on RDP table, but if your doing a multiple depth dive it gets hard to extrapolate that to a table
I purchased a knock off of a citizen aqualand duplex watch to back up my computer

 

[TartanFrog]

I don't get this, just about every tech diver makes do with a single SPG, and 2 wrist mounted depth/timing devices, so if that is good enough for someone doing massively more complicated/dangerous dives, why do you need more than that for a rec dive? Why add more complexity, more points of failure, more cost and more effort (from dragging all these extra dangles through the water)?

You're right! That is probably the real question. However, I keep hearing everyone talking about redundant equipment and wearing multiple computers etc. Afterall, we all carry triple redundant air sources. One of my instructors is very much into tech diving and except during classes she relies on an SPG, depth guages and watches. But then again, she has been diving for several years and has a ton of experience. Several of the other instructors do public safety diving so their viewpoint is from more of a professional level.

Just to clarify, the watch is not a dive watch that includes depth, etc. It is merely a watch that is rated to go to 200 meters. And I do keep everything tucked in and clipped.

 

[Garrobo]

You are making things more complicated than they are. I've been diving with an SPG which is 30 years old for the last 5 years. After you get some dives in you'll know about how far you can go on a tank of air either shallow or deep. That entails a 'decent' watch. Until you start diving spots like the Titanic or Andrea Dora I wouldn't worry about it. I dive with a used computer on the SPG hose and another one on my wrist. The reason for the one on my wrist is because a friend bought it for me a few years ago for helping him out with some wiring in his basement. Otherwise I wouldn't own it. Rather than sell it or let is sit around I use it although it is a pain. My dives go like this: Deep dive like 120-130 feet, 30-35 minutes bottom time start thinking about going up. Shallow reef, 30-60 feet, an hour. I can get by with a watch with that.

 

[captain]

Dives above 30' a watch and maybe an SPG, below 30' an analog SPG, an analog depth gauge, watch and two computers, one on my arm and one in my head.

 

[TSandM]

Well, I think the place to begin is to ask yourself what you would do if one of the gauges you now carry were to fail.

If my depth gauge fails, I will signal my buddy and we will proceed to end the dive. If I remain with him, I use his gauge as the reference for a reasonable ascent rate. (BTW, this is the one place where having a redundant instrument might make sense to me, and that only if one tends to dive with new or unknown buddies.) If my pressure gauge fails, I know a) what my last pressure reading was, and b) roughly what my gas consumption has been for the dive. I have also carefully maintained gas reserves according to my gas management strategy, so I know I have plenty left to exit the dive.

Taking spare gauges on an expensive, exotic trip makes sense to me. Taking them in the water for every dive doesn't.

And what do you mean by carrying triple redundant gas sources? Are you referring to the primary and backup regulator as redundant? Because they aren't, really . . .

 

[tr3a]

For recreational diving I would not worry about it.
Although others may have had different experience, in 40 years of diving I have never
had a gauge fail underwater (including some fairly extreme dives).
Just dive, gain experience then if a gauge does fail it is no big deal (assuming clear ascent to surface, ect).