slackercruster
Contributor
Pretty much all resort recreational dives are worked out for no decompression. Why do divers wear computers for such dives? I'm not for or against it. Just never used one, so what is the benefit for no deco diving?
Are dive computers overkill for most recreational divers?
- Thread starter slackercruster
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BioLogic
Contributor
One, I wear one because making sure I'm diving safe is my job, not the job of some resort people I don't even know.
Two, the resort people plan each dive as no deco, but how many dives can you make with the surface intervals provided? How soon after they put you back on shore are you ok to drive to altitude to see the cool volcano? The resort people couldn't tell me all of that, but I can get it from my dive records, and checking the computer is more convenient than working the problem out by hand.
Three, I don't think I'd be comfortable fifty feet down without knowing where my nitrogen status stood. I could use a bottom timer... if I had one. Or I can look at my NDL limit on the computer and see that I've got plenty of time left. I don't want to be swimming around without keeping track -- it would be like going without an SPG and expecting/hoping somebody else would end the dive before I ran out of air.
Four, if something does not go according to plan, I am keeping track of where I am and can react appropriately.
Five, I can look at my profiles afterwards and learn from them. What was my ascent rate, exactly where was the thermocline (ok, that's a local freshwater thing, but still), was I spot on when I thought I was maintaining constant depth? How deep was that school of fish fry I spent ten minutes just hovering and watching?
I am no tech geek, but I'll keep the dive computer, thanks.
Two, the resort people plan each dive as no deco, but how many dives can you make with the surface intervals provided? How soon after they put you back on shore are you ok to drive to altitude to see the cool volcano? The resort people couldn't tell me all of that, but I can get it from my dive records, and checking the computer is more convenient than working the problem out by hand.
Three, I don't think I'd be comfortable fifty feet down without knowing where my nitrogen status stood. I could use a bottom timer... if I had one. Or I can look at my NDL limit on the computer and see that I've got plenty of time left. I don't want to be swimming around without keeping track -- it would be like going without an SPG and expecting/hoping somebody else would end the dive before I ran out of air.
Four, if something does not go according to plan, I am keeping track of where I am and can react appropriately.
Five, I can look at my profiles afterwards and learn from them. What was my ascent rate, exactly where was the thermocline (ok, that's a local freshwater thing, but still), was I spot on when I thought I was maintaining constant depth? How deep was that school of fish fry I spent ten minutes just hovering and watching?
I am no tech geek, but I'll keep the dive computer, thanks.
pafindr
Contributor
Usually when you dive you are not at a constant depth.
Diving using standard table, such as PADI's RDP, you will get a bottom time of 25min at 90ft.
Since your depth can change due to buoyancy, bottom characteristics, etc. a computer will take that change and recalculate your bottom time.
Say if you're diving a wreck that is 90ft to the sand and you only spend 2mins at that depth. Then you come up to 80ft to check something out and stay there. Your computer will recalculate giving you more bottom time.
Diving using standard table, such as PADI's RDP, you will get a bottom time of 25min at 90ft.
Since your depth can change due to buoyancy, bottom characteristics, etc. a computer will take that change and recalculate your bottom time.
Say if you're diving a wreck that is 90ft to the sand and you only spend 2mins at that depth. Then you come up to 80ft to check something out and stay there. Your computer will recalculate giving you more bottom time.
some of the charter people for deep dives (even ones where you wont go much past 100') wont even take you out without one, but if all your doing is 2 shallow reef dives a day then IMO its a little overkill, but these days you can get an inexpensive one ($200) thats not much more than the cost of a decent dive watch...
Sasquatch
Contributor
I like the software that I loaded on my home computer as it allows me to download the dives, graph them out, add details about buddies, conditions and locations and then I print it out and snap it into my dive log for a detailed history.
Overkill? No.
Overkill? No.
Overkill? Not really.
Expensive? For the most part.
Absolutely necessary? No.
In reality, dive shops will sell new divers on the virtues of a computer and most new divers will buy one. But really, so what? If using a computer makes a diver more aware, terrific. If it helps them dive a little more safely, I'm good with that as well.
Once the new diver crosses over to experienced diver, and spends more time reading and figuring out the advantages and dis-advantages of using a computer, they will make the decision to keep using one or not.
For me, I like and use mine.
Expensive? For the most part.
Absolutely necessary? No.
In reality, dive shops will sell new divers on the virtues of a computer and most new divers will buy one. But really, so what? If using a computer makes a diver more aware, terrific. If it helps them dive a little more safely, I'm good with that as well.
Once the new diver crosses over to experienced diver, and spends more time reading and figuring out the advantages and dis-advantages of using a computer, they will make the decision to keep using one or not.
For me, I like and use mine.
diver 85
Contributor
answer to question: NO...get about 50% more BT if nothing else....
HBO MD
Contributor
I guess it's akin to saying that curtain air bags are overkill ; you may not need them at that moment, but it's reassuring to have them available.
Part of the challenge has been that the Navy tables were never really designed for multiples days of multiple dives. Add to that the intense diving profiles which sport divers embark upon while on vacation, the additional confounder that few divers carry tables with them while diving or no longer have a sound grasp of the tables, and computers are in fact a useful tool. There's no question that computers have advanced substantially since the old Hans Haas Deco Brain. This has been in the face of ongoing evolution of the tables; from square profiles through to multi level etc. The latest ones even have the capacity to incorporate heart rate, rate of air consumption into a more personalized physioloically based profile ; and hence their safety benefit.
Are there potential problems with them? Absolutely. Since with all electronics they may fail and hence this raises the issue of redundancy. Additionally, some divers feel they may embark upon a loosely structured plan as the computer will guide them through deco etc safely. This is not the case. Even curtain air bags will not protect you if you drive recklessly.
In any event, I feel that the capacity to tailor the level of conservatism, to address a more physiological profile, to maintain a detailed profile over many days definitely contributes to overall safety. And anything that enhances safety is worthwhile in my eyes.
Part of the challenge has been that the Navy tables were never really designed for multiples days of multiple dives. Add to that the intense diving profiles which sport divers embark upon while on vacation, the additional confounder that few divers carry tables with them while diving or no longer have a sound grasp of the tables, and computers are in fact a useful tool. There's no question that computers have advanced substantially since the old Hans Haas Deco Brain. This has been in the face of ongoing evolution of the tables; from square profiles through to multi level etc. The latest ones even have the capacity to incorporate heart rate, rate of air consumption into a more personalized physioloically based profile ; and hence their safety benefit.
Are there potential problems with them? Absolutely. Since with all electronics they may fail and hence this raises the issue of redundancy. Additionally, some divers feel they may embark upon a loosely structured plan as the computer will guide them through deco etc safely. This is not the case. Even curtain air bags will not protect you if you drive recklessly.
In any event, I feel that the capacity to tailor the level of conservatism, to address a more physiological profile, to maintain a detailed profile over many days definitely contributes to overall safety. And anything that enhances safety is worthwhile in my eyes.
vladimir
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I have done as many as 50 dives on one dive trip. If you string together enough no-decompression dives, guess what you get--a ceiling. That's what I need a computer for--repetitive dives in Papua New Guinea.
Computers are convenient and as has been mentioned before, continually re-calculate your nitrogen/oxygen exposure based on your current depth as opposed to tables which give you a calculation based on maximum depth (or multilevel, depending on what you were taught - IE the PADI wheel or eRDP ML or whatever). This can make a HUGE difference in bottom time. One wreck I used to dive sat in exactly 30 metres of water - by the rules of the RDP this means 20 minutes until you reach your NDL. However the wreck rises to a depth of about 14 metres, therefore it's perfectly possible to make a 50 minute dive on that ship if you multilevel carefully and are good with your air - no math required to tell you that's 30 minutes extra under the water thanks to your computer!
Are the essential for recreational diving? No
Are they useful? Yes
Are the safer? No.
The suunto Gekko - a fine, basic computer, will set you back between $200 - $300 depending on where you live. Many models of computer have computations based on research beyond the level of dive tables (the Reduced Gradient Bubble Model, for example) and therefore in some respects are more conservative than some tables. Most computers however will allow you to do dives that are not necessarily good for you - for example you might do a dive to 30 metres, go back up to 10 and if you descend again the computer will just keep ticking, even though we know 'sawtooth' profiles are bad things.
Use them, enjoy them, don't rely on them simply because they are computers.
Cheers
C.
Are the essential for recreational diving? No
Are they useful? Yes
Are the safer? No.
The suunto Gekko - a fine, basic computer, will set you back between $200 - $300 depending on where you live. Many models of computer have computations based on research beyond the level of dive tables (the Reduced Gradient Bubble Model, for example) and therefore in some respects are more conservative than some tables. Most computers however will allow you to do dives that are not necessarily good for you - for example you might do a dive to 30 metres, go back up to 10 and if you descend again the computer will just keep ticking, even though we know 'sawtooth' profiles are bad things.
Use them, enjoy them, don't rely on them simply because they are computers.
Cheers
C.
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