Are you suggesting that if one of the computer fails under water you and your wife could rely on the other computer for the remaining of the dive?
Sharing a dive computer....
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I have the luxury(?) of diving the same 20 or so sites repeatedly, some of which I dive weekly (this is a side benefit(?) of living on an island). One of the most fascinating pieces of "gear" I own is my copy of V-Planner (this is is proprietary dive planning soft-wear for our new divers). I toss in different profiles for my frequent 20 spots and see what my deco obligation is (or isn't). I do this mostly because I'm a math geek, but it's proved helpful as I've slowly developed a good sense of what different profiles at each of these sites requires. For me this means I'm comfortable in a pinch diving with only a watch (cheap G-Shock as mentioned earlier in this thread) and a manual depth gauge. I prefer to dive with my diver computer in bottom timer mode, but since sometimes it manages to fall out of my dive bag as I'm packing for work it makes me feel a lot safer diving "old-school."
What's the point of all that? Well, I guess I'd encourage the OP or anyone else who's interested in understanding how different variables effect their profiles to invest in some deco-planning software (which at an average cost of about 80.00 USD is cheaper then a dive computer) and some wet-notes and start to play along. Along with Mark Powell's Deco For Divers its given me a more solid understanding of decompression, especially in the context of no-mandatory stop recreational diving.
Michael
What's the point of all that? Well, I guess I'd encourage the OP or anyone else who's interested in understanding how different variables effect their profiles to invest in some deco-planning software (which at an average cost of about 80.00 USD is cheaper then a dive computer) and some wet-notes and start to play along. Along with Mark Powell's Deco For Divers its given me a more solid understanding of decompression, especially in the context of no-mandatory stop recreational diving.
Michael
DaleC
Contributor
Awap hit the nail on the head for me. On some known dives I would go with no depth gauge, watch or computer. I know how long my tank lasts and that's enough. On other more challenging dives I would not go without them.
The other thing is that it seems many divers use a computer to push the NDL limits and thus, worry about the slight variations between divers. If two divers are following a conservative dive plan they wouldn't have to micro manage their profiles to the same degree. Fortunately, I dive enough that I don't need to squeeze every last ounce out of every dive.
But, I would also agree, it's not a "Plan A" kind of idea.
The other thing is that it seems many divers use a computer to push the NDL limits and thus, worry about the slight variations between divers. If two divers are following a conservative dive plan they wouldn't have to micro manage their profiles to the same degree. Fortunately, I dive enough that I don't need to squeeze every last ounce out of every dive.
But, I would also agree, it's not a "Plan A" kind of idea.
Yeah, because DCS never happens....
Devon, you read it the way you wanted to which was quite different from what I had in mind based on my interpretation of Rhone Man's intervention.
RonFrank
Contributor
Most people responding to this act as if they are discussing a specific profile which they are not.
If one is doing 20' dives (LBTS comes to mind) having a computer and tracking NDL is rather worthless unless one is doing 3 hour+ dives. That just does not happen under normal conditions.
If diving to 120' on EAN32 and pushing NDL's one best be paying attention to the puter.
Then again I have buddies who use BT's only and like to do everything using tables. That's not me but I understand where they are coming from....
If one is doing 20' dives (LBTS comes to mind) having a computer and tracking NDL is rather worthless unless one is doing 3 hour+ dives. That just does not happen under normal conditions.
If diving to 120' on EAN32 and pushing NDL's one best be paying attention to the puter.
Then again I have buddies who use BT's only and like to do everything using tables. That's not me but I understand where they are coming from....
Interesting . . . Understand the sharing of computer as "bad" . . .
To throw in another variable, what if the non-computer diver had a backup timer and depth gauge? Is it still absolutely "no" to sharing the computer, given that both would know what the dive plan is?
See, the problem now is that most agencies do not teach the tables. While most of the old schoolers (I hate that term) would know how to revert to a tables profile and most of us old schoolers have the tables and a deco computer in our brains and track our dives even if we have a computer along for the ride, does the buddy in the OPs example have this ability? I doubt it. I am not saying it is hard to do but only that most divers today simply have no training or real experience diving the tables or any other type of dive planning that does not rely on a computer as the central tool.
And, it is really somewhat difficult to dive tables and a computer in a buddy team. It can become confusing with the table diver usually the limiting factor.
N
DevonDiver
N/A
4 pieces of information that are critical for every diver:
1) Depth
2) Time
3) Gas
4) NDL
Does it matter how you get that information? No. You just have to have it.
Depth can be gained from a variety of sources; computers, depth gauges, knowledge of the dive site...even from marked lines. It is not feasible to accurately estimate depth by visual, or other, indicators.
Time can be gained from several sources; computers, watches and other gauges. It's not feasible to accurately measure time over the space of a dive by counting.
Gas can be gained from either an SPG or J-valve. Knowledge of your air consumption, used to predict gas use over time isn't the same as knowledge of your actual gas status...and doesn't mitigate against certain risks, such as; gas leak, accelerated SAC etc.
NDL can be gained from a dive computer, tables, desktop/laptop software or mental calculation (i.e Ratio Deco). All are valid, providing the diver follows the correct procedures, plans the dive and follows the plan.
Other information, such as; ascent speed, no-fly time, emergency deco etc aren't critical; but they do help to further mitigate against risk and add convenience. All of this information is available to divers, without reliance on a dive computer. A computer just adds convenience and can reduce task loading.
Every agency and most experienced divers will recommend that every diver has independent access to that information. The logic behind that recommendation is that it allows each diver to mitigate against a range of foreseeable scenarios; the primary risk being that of buddy separation.
Sharing a dive computer essentially puts one diver into the role of 'trust me'... where they are completely reliant on a buddy to provide that critical dive information. It's impossible for that diver to plan or track a dive on their own. It doesn't add risk, but it does fail to mitigate against potential risks that have been proven to exist.
1) Depth
2) Time
3) Gas
4) NDL
Does it matter how you get that information? No. You just have to have it.
Depth can be gained from a variety of sources; computers, depth gauges, knowledge of the dive site...even from marked lines. It is not feasible to accurately estimate depth by visual, or other, indicators.
Time can be gained from several sources; computers, watches and other gauges. It's not feasible to accurately measure time over the space of a dive by counting.
Gas can be gained from either an SPG or J-valve. Knowledge of your air consumption, used to predict gas use over time isn't the same as knowledge of your actual gas status...and doesn't mitigate against certain risks, such as; gas leak, accelerated SAC etc.
NDL can be gained from a dive computer, tables, desktop/laptop software or mental calculation (i.e Ratio Deco). All are valid, providing the diver follows the correct procedures, plans the dive and follows the plan.
Other information, such as; ascent speed, no-fly time, emergency deco etc aren't critical; but they do help to further mitigate against risk and add convenience. All of this information is available to divers, without reliance on a dive computer. A computer just adds convenience and can reduce task loading.
Every agency and most experienced divers will recommend that every diver has independent access to that information. The logic behind that recommendation is that it allows each diver to mitigate against a range of foreseeable scenarios; the primary risk being that of buddy separation.
Sharing a dive computer essentially puts one diver into the role of 'trust me'... where they are completely reliant on a buddy to provide that critical dive information. It's impossible for that diver to plan or track a dive on their own. It doesn't add risk, but it does fail to mitigate against potential risks that have been proven to exist.
No, it's not. I would say that, in the majority of the dives I do in a year, my buddy and I could trade computers and nothing untoward would ensue. We stay together -- that means almost within kicking distance -- without stress or hassle. This was my whole point that if buddies stay where they ought to be, their profiles won't be different enough to impact the risk of DCS to any significant degree at all.
As someone else said, there are profiles that are so benign that you could do them WITHOUT a gauge at all . . . for me, anything that is 60 feet or less at home, on my habitual 32%, will run me low on gas before decompression is an issue. Edmonds Underwater Park, with a max depth of 40 feet, is a place where I'll get seriously hypothermic before I am short on gas OR no deco time.
Novice divers are advised not to share a computer, because they don't share a profile. Trained divers can nearly map out a price profile if they want to do so.
buton
Contributor
Since I am new to this and safety is a big issue, I though my wife and I could do this but saving money to buy just 1 computer for both does not worth it my life does not cost 300 usd. We already bought regulators and we are waiting til next month to buy our computers...
Good for you!!!
Don't forget to look around for used computers. As people work their way through training and take on ever-more technical and challenging dives, or are just gadget geeks :blush:, good used computers come up for sale. Even a good solid Tec computer like the ScubaPro Uwatec 2G is pretty darned inexpensive, and will take you a long way.
Fair warning - I'm a Uwatec fan but have no business nor financial interests in the company. Just love them!
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