New divers and computers

[spectrum]

I hit the problem of being off tables on my 3rd dive after cert, which was also my first boat dive. Even as a real airhog, a multilevel dive of 35 minutes to 65' max, followed by another dive an hour later is off the charts. The rental reg set included a computer, for just this reason.

Then it was appropriate for your diving, everyone needs make their own decisions. For the many new divers doing shore dives to 40 feet there may be different priorities. Many divers do not have access to affordable boating or the desire to enter deeper water. That's all I'm saying.

Pete

 

[scubatexastony]

your safety stop and accent from it in your total bottom time. NAUI says you don't have to include that in calculating your total bottom time. Thinking outloud....

 

[wheelietaco]

Why not use both. Plan using tables then compare with your computer. Follow your plan with the tables and use the computer for ascent rates, bottom time, temp, depth, and if need be deco. Tables leave a margin of safety in there, and it is your health and maybe your life we are talking about. You can choose what you want to do. Push the limits a bit or stay a bit off of them.

 

[jeckyll]

Leaving alone the "off the tables" comment for a moment, are you planning on doing some shore diving? I have found that most of our dives here are 'checkmark' profile dives (mostly because we make them so). If I was to try and use the RDP for these dives I should be bent like a pretzel.
For instance: Dive to 105 fsw in cold water (for RDP add 10 feet to total depth for safety, making it 115 fsw). Dive lasted 35 minutes. Two hour SI and dive to 58 fsw for 47 minutes. Now, dive one had a avg depth of 50 feet, dive two had an average of 32 feet. Both had significantly more than 3 minutes at < 20 feet. Perfectly safe and we actually never got within single digits of NDL _and_ I was diving Saftey Factor 1 (i.e. added conservatism).

If you are planning to do nothing but square profiles then tables are fine, but they will not help you much if you do shore dives with completely non-square profiles (i.e. checkmark shape).

Just my $0.02

Bjorn

 

[jeckyll]

....
*edit*
I know that the tables say you can spend 20minutes at100', and my computer says 30 minutes at 100'. just smart on what you do.

What computer do you dive that gives you 30 minutes at 100'?

 

[Amberjack]

Subatexastony - I actually think we did count our safety stop and ascent from there into the total bottom time. So, another measure of conservatism there - good point.

Bjorn - I think there could definitely be shore dives in my future if I start diving locally. Another good point.

 

[wheelietaco]

Sorry my bad was looking at the wrong depth. Genesis react pro

 

[1_T_Submariner]

Good discussion. I think it is important to know the tables but, the computer will increase you bottom time. A backup is a good Idea too.

 

[halocline]

I feel like a computer is a real benefit for a new diver as it helps to track ascent rate much more accurately than an analogue depth guage. DCS in a new diver diving single tanks (AL80 for example) is much more likely to be caused by poor ascent control than by excessive bottom time; you'll simply run out of gas before you can go too far into deco, ASSUMING your depth is within reason for a new diver and your surface intervals are nice and long. But, it's very easy for a new diver to blow the ascents, and a computer alarm telling you to slow down is very helpful in this case.

Sure, sure, sure, let's all learn the tables, whatever. By far the biggest and most important skill new divers have to learn is to control their profiles, especially ascent rate and profile. Computers can really help this. So can bottom timers with ascent rate indicators and alarms, but why not get a computer? To be honest, once you've gotten some experience, you'll be paying much more attention to the depth/ascent rate/bottom time displays on the computer and less to NDL anyway. That's because you will have developed the ability to plan and dive profiles which don't cause NDL complaints from most computers, and you'll be more interested in the actual dive data rather than the theoretical deco model.

 

[PaulChristenson]

You ARE joking, aren't you? Clearly this was a case of a multilevel dive that was in reality conservative, even though when calculated using square profiles on the tables was a few minutes into deco.

I'm not advocating ignoring tables, relying upon someone else to do the deco tracking, or using someone elses computer, but OTOH, the situation described doesn't call for O2.

Yes I was joking...

but it appears that my computer burped...and the rest of my message is gone:huhu:

No after the O2 question

No comment about if you get a computer...make sure you spring for one that does at least one nitrox gas option


and no signature either...Geez

Paul in VT