Cosimo_Zaretti
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It seems my sense of humour is a little abrasive. I have replaced my response with this kitten.
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Nitrox without dive computer?
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LowDrag
Contributor
This is listed at the top of this forum...you may want to read it again and then again once more:
Please note: This forum has special rules. This forum is intended to be a very friendly, "flame free zone" where divers of any skill level may ask questions about basic scuba topics without fear of being accosted. Please show respect and courtesy at all times. Remember that the inquirer is looking for answers that they can understand. This is a learning zone and consequently, any off-topic or overly harsh responses will be removed.
To the OP...as suggested, your wife's life is more valuable than a $200 - $300 computer. I hope you will listen to other posters on this thread and get her to dive with a computer. Good luck and safe diving.
Simply put I wouldn't dive without a computer anytime or allow anyone to dive with me under those conditions. Either they understand what they are doing, or dive with someone else. The only exception to this is new diver asking for help, knowledge and experience. I could have babied my wife when we did tech deco and extended range, but I refused to and ensured she learned and had the knowledge, no sympathy. I value her life and mine and to do less could and would put us both at significant risk.
If your wife is OK with tables and "understands them" then no issue, however if she is looking for a free ride because she can't be bothered learning or doesn't really want to pick up the knowledge, the do both of you a real favour...........................DON'T Do the course with her, and leave her on air, however she would still have to use air tables so same issue.
Do you have to baby her now, work out all the dives, times etc? My assumption is that currently you both use tables only???????
A significant risk is, what happens if you lose each other, she stays down looking and exceeds her NDL, how will she know this and how will she recover from it? You have to assume Murphy will strike, and he will. How would you feel if something bad happened, would you be happy then that you saved a few hundred dollars? I only would if it was my ex wife (not really but it makes me smile thought). You cannot assume all will be well. Assume and plan for the worst.
We both use exactly the same computers (ProPlus 2 and Petrel each). So no matter what style we dive (rec or tech) we have similar profiles but not always the same. Its also a good check against each other too and we use the most conservative profile throughout the dive.
If your wife is OK with tables and "understands them" then no issue, however if she is looking for a free ride because she can't be bothered learning or doesn't really want to pick up the knowledge, the do both of you a real favour...........................DON'T Do the course with her, and leave her on air, however she would still have to use air tables so same issue.
Do you have to baby her now, work out all the dives, times etc? My assumption is that currently you both use tables only???????
A significant risk is, what happens if you lose each other, she stays down looking and exceeds her NDL, how will she know this and how will she recover from it? You have to assume Murphy will strike, and he will. How would you feel if something bad happened, would you be happy then that you saved a few hundred dollars? I only would if it was my ex wife (not really but it makes me smile thought). You cannot assume all will be well. Assume and plan for the worst.
We both use exactly the same computers (ProPlus 2 and Petrel each). So no matter what style we dive (rec or tech) we have similar profiles but not always the same. Its also a good check against each other too and we use the most conservative profile throughout the dive.
LowDrag
Contributor
It seems my sense of humour is a little abrasive. I have replaced my response with this kitten.
G'Day mate...nice retraction. Thank you
I have seen this a couple of times. The husband gets the computer and the wife tags along. I haven't been able to understand it. If you are both divers, using Nitrox, you should both have computers. I would think both computers should be equal in capabilities and use similar algorithms. Yes a couple hundred dollars is a lot of money but for the safety of my wife I would want something for her of equal capabilities and compatible with what I am using.
If you're diving off a boat that caters to vacation-type divers, they sometimes ask as part of a gear check if everyone has a computer. Your wife will either have to answer that she has a computer or some other reasonable reply, such as "I'm diving tables." If she's diving tables while you're diving a computer, you will compute substantially different amounts of no-deco time from each other, and you will have to be careful to end the dive based on the lesser of each of your computed no-deco times (mostly likely it will be hers if she is diving tables). It will minimize complications if BOTH of you dive with a computer.
There are even threads on SB where someone asked whether there is an advantage for both buddies to have the SAME computer. Mixed responses on that question, but you should be getting the point here. Save yourself some hassle and get a computer for each of you. Almost all computers are Nitrox capable these days, so you will have the option of setting the computer for Nitrox or air as you may wish for a particular dive.
It seems like the "Nitrox" aspect of your question is a red herring, as your question is not really about Nitrox but more about the prospect of you relying on a computer for computing your no-deco time while your wife is relying on a table for computing her no-deco time. If that's really the crux of the matter, then it makes no difference whether you are setting your computer for Nitrox or air mode while your wife is selecting either her Nitrox or air table.
I hope your question is not simply whether it's okay for a diver to use nothing at all to compute no-deco time but rather rely on his buddy's computation. That is NEVER okay. Each diver needs to compute his own no-deco time for each dive, whether it's by means of tables or a computer. We were all taught that in OW class.
There are even threads on SB where someone asked whether there is an advantage for both buddies to have the SAME computer. Mixed responses on that question, but you should be getting the point here. Save yourself some hassle and get a computer for each of you. Almost all computers are Nitrox capable these days, so you will have the option of setting the computer for Nitrox or air as you may wish for a particular dive.
It seems like the "Nitrox" aspect of your question is a red herring, as your question is not really about Nitrox but more about the prospect of you relying on a computer for computing your no-deco time while your wife is relying on a table for computing her no-deco time. If that's really the crux of the matter, then it makes no difference whether you are setting your computer for Nitrox or air mode while your wife is selecting either her Nitrox or air table.
I hope your question is not simply whether it's okay for a diver to use nothing at all to compute no-deco time but rather rely on his buddy's computation. That is NEVER okay. Each diver needs to compute his own no-deco time for each dive, whether it's by means of tables or a computer. We were all taught that in OW class.
Damselfish
Contributor
The question is, why "she has no interest in wearing or carrying a separate dive computer aside from the usual SPG"? Need to know that before figuring out what the best next step is.
Of course she can dive Nitrox on tables, but that pretty much restricts both of you to Nitrox table profiles, similar to how you are presumably diving now. In some cases that will be good enough, in others a big loss of potential bottom time. 2 divers sharing a computer could be done in theory but is widely considered bad practice. It still doesn't hurt to take the class. Perhaps after taking the class she will change her mind.
Of course she can dive Nitrox on tables, but that pretty much restricts both of you to Nitrox table profiles, similar to how you are presumably diving now. In some cases that will be good enough, in others a big loss of potential bottom time. 2 divers sharing a computer could be done in theory but is widely considered bad practice. It still doesn't hurt to take the class. Perhaps after taking the class she will change her mind.
Basic instruments are an spg, depth gauge and a watch with which you plan your dive using tables and calculate end pressure group etc
Next step up is using a computer, I bought one for my daughter when she did her Nitrox course several years ago, I would not be wanting to buddy up with somebody using air when I am using Nitrox.
Next step up is using a computer, I bought one for my daughter when she did her Nitrox course several years ago, I would not be wanting to buddy up with somebody using air when I am using Nitrox.
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Adobo
Contributor
I know tons of divers that use just a bottom timer and a depth gauge to dive nitrox. Heck, even dive trimix and multi deco gases using just a bottom timer and depth gauge.
The thing about diving without a computer is that you will have to use more of your brains, not less of it. You will have to mentally track what your no deco limits are on any and every dive. Meaning, just because they brief you that the dive is to 100 ft doesn't mean you will actually do a dive to 100ft. You might bottom out at 85 ft and average 70ft for the duration of the bottom portion of the dive. No deco limits (as you know) are different for 100 ft to 85 ft. And from 85 ft to 70 ft.
I have dived during numerous family vacations. Multiple days, multi level dives. I've never found anyone who has actually stayed down longer than me just because they use a computer and I don't. I have found a few who could stay down longer due to better SAC rates.
And by the way, I question this notion that dive computers give you more bottom time. Dive computers work on models, they do not physically monitor your individual status. Dive computers are more precise in calculating and tracking your actual depths during a dive and determining the theoritical inert gas load. However, typical dive computers don't know if you are feeling cold or if you are dehydrated of if you consumed alcohol (which people seem to do during vacations). Computers also don't know your body type/composition or your current fitness level. Things that are all considered factors in a diver's pre-disposition to DCS. So to me, computers are more precise. Not necessarily more accurate.
But again, not using a computer is a path to more involved dive management. If your wife wants to use the computer between her ears to manage her no deco times, then no computer is perfectly valid way to do that. If you wife is wanting to lessen the thinking/mental task loading that is involved in diving, a computer is a better way to go.
Nitrox tables work for planning dives without a computer, and I use them in planning dives and defining pressure groups after as part of keeping all my skills current. However, what is said above is true:
1. 2 people diving off one computer is a no no
2. Computers maximize bottom time by making an unlimited number of multi-level dive calculations as you dive
3. Most if not all new computers have a nitrox programmable mode.
4. Individual dive computers are the norm for every diver these days, and some boats REQUIRE each have to have their own computer.
What has not been said is that there are still advantages to diving nitrox without a computer, including enhanced bottom time when using an RDP vs the DSAT nitrox tables, reduced nitrogen absorption for same depth /time dives vs the same dive on air, and for me, less fatigue factor.
If you wife dives a lot, she should have her own computer.
DivemasterDnnis
1. 2 people diving off one computer is a no no
2. Computers maximize bottom time by making an unlimited number of multi-level dive calculations as you dive
3. Most if not all new computers have a nitrox programmable mode.
4. Individual dive computers are the norm for every diver these days, and some boats REQUIRE each have to have their own computer.
What has not been said is that there are still advantages to diving nitrox without a computer, including enhanced bottom time when using an RDP vs the DSAT nitrox tables, reduced nitrogen absorption for same depth /time dives vs the same dive on air, and for me, less fatigue factor.
If you wife dives a lot, she should have her own computer.
DivemasterDnnis
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