Do I really need a computer?

[Sordello]

Wow! the black art of diving!!! something magical and misunderstood. Not a worthy subject to discuss. The RDP is setup to be safe under the worst case conditions. The computers are likely to use the same formulas that are setup by PADI. So whats the difference. I am going to go out on a limb and say that it is likely that the dive computer that anyone is using is not using any different math that is found on a RDP. Why risk the lawsuit if someone is suffering DCS because of using the computer.
Does any one here know if a dive computer uses different calculations from a RDP to determine nitrogen in the blood. Likely not, because it would leave the programmer subject to lawsuits.

 

[Rafael]

I will say no you do not need one but it is really nice to have one i have a cobra is very nice yes is not cheap but my dives are longer and i feel better having one, think about getting one after you use it a couple time you will love it.

 

[Randy43068]

Wow! the black art of diving!!! something magical and misunderstood. Not a worthy subject to discuss. The RDP is setup to be safe under the worst case conditions. The computers are likely to use the same formulas that are setup by PADI. So whats the difference. I am going to go out on a limb and say that it is likely that the dive computer that anyone is using is not using any different math that is found on a RDP. Why risk the lawsuit if someone is suffering DCS because of using the computer.
Does any one here know if a dive computer uses different calculations from a RDP to determine nitrogen in the blood. Likely not, because it would leave the programmer subject to lawsuits.

All tables include three parts: 1) no-decompression time limits; 2) surface interval times; 3) residual nitrogen times.

How they arrive at the above 3 things is a little different for different computers.
A computer program commonly known as an algorthm keeps the diver updated with "calculated" not measured information. Some use RGBM, some use Haldane, some use Buhlmann, or even the modified Buhlmann. (It's early and I'm on my first cup of coffee so forgive me if I've forgotten a few of them.) So while similar computers do in fact use different algorithms than the RDP. As you might have concluded some computers are more consertative than others are. I can't remember the make or model but some have been recalled because they weren't making the calculatiions properly, and many divers who were using them got bent. It took a lawsuit to get 'em off of the market. The magazine Undercurrent has a few articles about it.

Hope this helps your understanding of the things.

Incidentally, I'm spending my money on dive trips, and more training instead of a dive computer. It's a nice gee-wiz thing, but not really needed.
(and forgive my disjointed writing. It's early... remember the coffee thing? I need more)

 

[cnctina]

Did anyone mention that most dive charters put time limits on your dives so they can keep their charters on time. Not much good to have 10 more minutes of botom time left on your computer if you have to be back to the boat now.

 

[Cold_Under_Here]

Wow! the black art of diving!!! something magical and misunderstood. Not a worthy subject to discuss. The RDP is setup to be safe under the worst case conditions. The computers are likely to use the same formulas that are setup by PADI. So whats the difference. I am going to go out on a limb and say that it is likely that the dive computer that anyone is using is not using any different math that is found on a RDP. Why risk the lawsuit if someone is suffering DCS because of using the computer.
Does any one here know if a dive computer uses different calculations from a RDP to determine nitrogen in the blood. Likely not, because it would leave the programmer subject to lawsuits.

Computers and tables do indeed vary in gas models: (previously stated) Reduced Gradient Bubble Modelling, Haldane, Buhlmann...some (ie RGBM) take into account bubble size in the blood, whereas other models model only gas absorption and offgasing....etc

You can pick the model you use with tables...I can use PADI tables or RGBM NAUI tables if I wish....they use different gas models, have varying bottom times, and different stops (safety and or deep stop).

 

[Sordello]

Has anyone here used the electronic PADI RDP calculator. It will do metric calculations and is a bit cheaper than buying another wheel. I will not give up using the wheel just for one reason. I would not want to be seen fumbling around when asked to use it to figure out the NDL for the second dive of a day.

 

[rls]

I have never used a dive computer before.
I have always used my PADI dive tables and my PADI repetative dive workslate.
One nice thing about the workslate is that you fill out a "contingincy planning " section on the botom of the workslate in the event you marginally exceede your planned dive depth and adjust your DC stop time.
That said , the other day I went on a dive to Catalina, the ships captian said all should have dive computers ready,we (me and buddy) did no thave computers so we just kept quiet.
A note of tradegy that day as well: One of the lady divers had a heart attack and died right before everyone after her first dive. She was 100 lbs overweight, large gut and type-II diabetic,........she should have not been diving at all!!!!
I wonder if she planned her death, I know the captian was worried and anger at the same time over the event. Her husband seemed very sad but didnt realy seem to cry much??????

Party-on!

 

[sff]

This has been an interesting thread. Enough that I thought I would respond to it. First, my qualifications to comment. I have over 1,700 dives, of which all but the first 100 have been on a computer. I was one of the first in the world to use a dive computer, because I was one of the first to buy an EDGE (the first commercial computer which I bought in 1984). Which I still own to this day. I currently dive a SmartCom, for reasons not relevant to this thread.

NO. You don't need a dive computer.

If your diving is simple. If you don't dive much. If you dive very conservatively. If your air consumption is bad. If you never do multi-day diving. If these are true statements, then you won't miss a computer.

But for me, a computer is an absolute necessity. In fact, such a necessity that I dive with a small backup computer just in case my regular computer malfunctioned. Which it did once (using an ORCA Phoenix).

I can't imagine diving without a computer. I'm quite capable of figuring out multilevel diving using the tables. I'm a physician who use to be chamber certified in a previous career. And I don't give up using my brain diving with a computer. But the point is that I don't want to figure out dive tables. The computer frees me to concentrate on other things. And it allows me to dive any profile I want without having to determine it a priori and follow it slavishly. And since moving into nitrox, using a computer is even more freeing. And finally, they are not safer, but they do allow you to extend bottom time safely. People who haven't used a computer don't know what they are missing. I remember having conversations like this in the late 80s when only a few people had computers. I didn't realize that things hadn't changed.

But let's look at the economics of computers. They are not that expensive. $300 or so gets you a good one. But look at it realistically. If all you do is dive locally you may not need one. But a good computer will last years and can end up costing far less than a dollar a dive. Especially if you dive a lot. Which makes them even more valuable.

Yes, you don't need a dive computer. But I won't dive without one. And if we ever go on a dive together. That's fine. You can dive without a computer. Just don't complain having to wait for me up on the boat. Take care,

 

[Sordello]

A note of tradegy that day as well: One of the lady divers had a heart attack and died right before everyone after her first dive. She was 100 lbs overweight, large gut and type-II diabetic,........she should have not been diving at all!!!!
I wonder if she planned her death, I know the captian was worried and anger at the same time over the event. Her husband seemed very sad but didnt realy seem to cry much??????

Don't be suprised by the lack of crying. My wife passed away 4 years ago - on this day - from cancer while in my arms. I didn't cry for a long time and often woke up in the morning thinking it was all a mistake and Rina would be here with me.

 

[Goose75]

Don't be suprised by the lack of crying. My wife passed away 4 years ago - on this day - from cancer while in my arms. I didn't cry for a long time and often woke up in the morning thinking it was all a mistake and Rina would be here with me.

Shock, disbelief, disability to comprehend and the disire to think of everyone except yourself all play a part. My sister was lost when I was thirteen and I was unable to cry at my own grief for a long time. Strong emotional responses (whether anger, grief, etc) hit me after my mind comes to grips with the reality of what has happened.

I agree with Sordello, the husbands response may have been perfectly normal.