Sharing a Dive Computer

[halocline]

Wow girl, put those fangs away. My information came straight from the mouth of the owner of my LDS.

Well, that explains why it's wrong.

 

[halocline]

simpley put, just don't use a computer for more than 1 person its the safest way of assuring that no one gets injuried etc....

This is exactly what's wrong with the whole nonsense about reliance on computers in the first place, the assumption that safety is a result of using a computer. Safety in diving is a result of intelligent, educated, informed DIVER BEHAVIOR with regards to depth/time planning and profile management.

Computers are convenient and give most divers much more bottom time without theoretically increasing risk of DCS. That's a good thing, but assuming that your computer is keeping you safe, and therefore substituting it's use for careful planning and execution, is a bad thing.

For many, many dives, computer use just does not make that much difference because the profiles are quite far from NDLs. If you want to be safe, really really safe, just dive profiles that don't even come close to NDL, and ascend very slowly.

 

[Herk_Man]

This is exactly what's wrong with the whole nonsense about reliance on computers in the first place, the assumption that safety is a result of using a computer. Safety in diving is a result of intelligent, educated, informed DIVER BEHAVIOR with regards to depth/time planning and profile management.

Computers are convenient and give most divers much more bottom time without theoretically increasing risk of DCS. That's a good thing, but assuming that your computer is keeping you safe, and therefore substituting it's use for careful planning and execution, is a bad thing.

For many, many dives, computer use just does not make that much difference because the profiles are quite far from NDLs. If you want to be safe, really really safe, just dive profiles that don't even come close to NDL, and ascend very slowly.

Matt, is that what you do?

 

[halocline]

Actually, most of my local dives are 20 ft maximum and I never use a computer for those. The one place I really enjoy diving locally is 20 ft deep, sooo....

When I dive in the caribbean I usually run my planned profiles through the wheel (I kind of enjoy the wheel) and dive with my computer. But I almost never push NDLs, have never gone into unintentional deco, and I'm very careful about slow ascents, use multi level profiles and extended stops. What's the rush? IOW, if my computer quit on almost every dive that I do, I could easily finish it with a buddy for depth and my watch for time, and maybe a 10 minute stop at 15 ft.

The FGB, where I also like to dive, is a deeper, square profile that is perfect for EAN32, and I use the computer but make nice long stops. I would not want to dive there on air.

How about you?

 

[diverrex]

This is exactly what's wrong with the whole nonsense about reliance on computers in the first place, the assumption that safety is a result of using a computer. Safety in diving is a result of intelligent, educated, informed DIVER BEHAVIOR with regards to depth/time planning and profile management.

Computers are convenient and give most divers much more bottom time without theoretically increasing risk of DCS. That's a good thing, but assuming that your computer is keeping you safe, and therefore substituting it's use for careful planning and execution, is a bad thing.

For many, many dives, computer use just does not make that much difference because the profiles are quite far from NDLs. If you want to be safe, really really safe, just dive profiles that don't even come close to NDL, and ascend very slowly.

Exactly. Two buddy divers, one with a computer and the other without, making a dive where they don't even come close to NDL are much safer than two divers both with computers diving within 1 minute of NDL.

Disclaimer to new divers: I'm not suggesting you share computers, in fact I suggest everyone have one (I use two on every dive). And as others have pointed out with the total cost of diving the extra $300 is only a small part. But as Mattboy points out don't fall into the trap that since you are using a computer you are now safe. Make sure you understand all the principles behind decompression and limits. The computer is only a tool to be used with the understanding, not a fail safe safety device.

 

[Herk_Man]

Actually, most of my local dives are 20 ft maximum and I never use a computer for those. The one place I really enjoy diving locally is 20 ft deep, sooo....

When I dive in the caribbean I usually run my planned profiles through the wheel (I kind of enjoy the wheel) and dive with my computer. But I almost never push NDLs, have never gone into unintentional deco, and I'm very careful about slow ascents, use multi level profiles and extended stops. What's the rush? IOW, if my computer quit on almost every dive that I do, I could easily finish it with a buddy for depth and my watch for time, and maybe a 10 minute stop at 15 ft.

The FGB, where I also like to dive, is a deeper, square profile that is perfect for EAN32, and I use the computer but make nice long stops. I would not want to dive there on air.

How about you?

I'm new to the computer diving thing. Had always used tables before. I typically don't go below 60 feet just because the colors start to go away there and most places I've dove haven't been any deeper. So I know that with as long as it takes me to suck down an 80, if I do a safety stop and don't ascend faster than my bubbles, I'm ok. I do take my tables with me though in case I have a computer die on me. Then I can look at my max depth and figure out my SI based on a square dive profile. I don't dive often enough to do anything extreme so most of my stuff is conservative and not pushing any limits.

 

[jbtut]

1. There's no possible way that a diver who stays at a shallower depth than another diver for an entire dive will take on more nitrogen. (Save for exceedingly unusual circumsances where currents might cause one area of water to be denser than another or something similar)
2. Bottom time limits and profiles are based on accumulation and dissipation of nitrogen
3. Therefore the profile and resulting nitrogen levels of the diver who stays higher than the individual with a computer will always be diving a more conservative profile.
4. Therefore if the computer wearer is always lower/deeper, and neither diver surfaces too quickly, there should be no problem with two people using one computer, as the non-user will always be safer than the computer wearer.

5. What a particular dive agency says or doesn't say has zero bearing on whether something is safe or not. It may very well be good advice, but physics and physiology determine whether something is safe or not.

That said, I generally reference my ascent rate based on my computer. Moreover my computer alarms me if I start to rise too quickly which does happen occasionally when I'm preoccupied taking pictures of something and might start to follow it along a wall and end up tracking upward. Second it is a very handy way to measure the safety stop. It's all automated.

While I think two people could share a computer in theory, that would require the second diver to spend a lot of time paying attention to his or her buddy and that would make the diving less enjoyable. Additionally if the non-computer diver does make a mistake and lose track of the computer diver they have no idea whether they are safe or not. Moreover most experienced divers have computers. It's likely to be the newer divers that would want to share one.

For those reasons I don't think I would want to share one. And my wife and I both have one so it probably isn't going to occur unless someone else goes with. And if they want to try to stay above me and trust my computer, I really don't care. However, I would not trust someone else's computer.

 

[NCadiver]

jbtut since you did not provide any parameter if I am diving nitrox and you are diving air you are going to absorb more nitrogen them I will even though you are above me.

Currents do not change the density of water. Depth and time are the main factor on nitrogen absorption you may want to re-read your o/w book and take a class on deep diving or the advance class.


Dive agencies have put in a lot of time and money in to make the sport safe and fun, so they know a lot more about diving then you do. You need to get more diving experience and knowledge before giving advice out on safety.

This is from SDI, Netdoc you may want to re-read the SDI Instructor manual.
Steve, SDI/TDI HQ
Dive Industry Professional
SDI Standards are very clear: Each diver MUST wear a personal dive computer. The ONLY exception noted is a discovery scuba.

Sharing a computer is against just about every industry standard I can think of.

FYI, I just spoke with our V-P Training, Sean Harrison, and after he stopped choking on his inhaled coffee, he confirmed the standards for me. No ambivalence at all.
__________________

Best Regards,
Steve Lewis
Marketing & Communications Director
SDI/TDI/ERDI
steve.lewis@tdisdi.com International Training :: Home :: :: English

 

[diverrex]

Sharing a computer is against just about every industry standard I can think of.

.
__________________

Best Regards,
Steve Lewis
Marketing & Communications Director
SDI/TDI/ERDI
steve.lewis@tdisdi.com International Training :: Home :: :: English

This is what is wrong about so much education and training these days, in all fields. They would rather you learn simple statements and apply them in some knee jerk gospel fashion in all circumstances than really developing a deeper understanding of the facts and situations and be able to intelligently apply your knowledge across a range of differing circumstances.

Makes me want to run out and share my buddy's computer on a 30' 50 minute dive, just for the fun of it. Oh what a scuba rebel I must be.

For the record I'll repeat that I wear two dive computers on all my dives. I just think that the admonition "never ever share a dive computer" is a little silly.

 

[fisheater]

This is what is wrong about so much education and training these days, in all fields. They would rather you learn simple statements and apply them in some knee jerk gospel fashion in all circumstances than really developing a deeper understanding of the facts and situations and be able to intelligently apply your knowledge across a range of differing circumstances.

Gotta start someplace!

We don't teach our kids to drive while eating, changing the radio and fiddling with a GPS nav system. But we do it.