Very clever marketing :-)

[Rainer]

Great response

For minimal deco diving, I agree that MOD is really my only operational concern. And thanks to DIR's standardized gasses and standardized MODs, there seems to be ridiculously little to worry about. Dive 32% to 100'. Dive 30/30 to 120'. Don't worry about 130' until Tech 1, which should be years from now--if ever.

I was really just curious. Trust me on this one: If I'm not willing to "pose" by wearing doubles I don't need, I won't be posing by wearing a trimix and CCR-capable dive computer either. The only actionable issue for me right now is that I am planning a trip South in a few months and I want to dive in the same configuration I'll be taking to GUE-F.

I already own a Suunto Gecko, which does not have a gauge mode. It probably won't lock me out if I stick to minimal deco dives, so I imagine can use it. I bought a bungee boot for it (see above). That being said, my wife doesn't own a computer, so I was vaguely thinking of buying myself a bottom timer/depth gauge and handing the Gecko down.

I also have the mechanical depth gauge that came in my now-discarded console. I was wondering about fashioning a boot for that and bungee-ing it to my arm. So swining to the other extreme from using a computer in gauge mode, what about using a depth gauge and timing the dive with the rotating bezel on an old-fashioned dive watch?

The failure mode on the watch is obviously failing to reset the bezel to "zero" when entering the water. I wasn't sure about the depth gauge. Is it accurate enough to work the one minute ascents?

In preparation for GUE-F, I sold my Gekko for exactly what it cost me to buy a used Vyper (Gekko+gauge mode) in great shape from TDS. You could consider doing the same. I recently picked up a gently used Uwatec BT on TDS for $100. A used Vytec DS on TDS for $250 (with DSS boot). Deals are out there. Sell the Gekko and pick up what you want.

 

[Gombessa]

Also, I wouldn't worry too much about the battery on the Uwatec BTs. They're designed to last something like 10 years; chances are you'll have upgraded or replaced it by then (and if not, $200 every 10 years isn't exactly a bad value).

 

[John_B]

If I were you I'd just get the Tec2G and be done with it.

The numbers on the display are just a tad smaller than I'd like but its not a huge deal, and the primary display in (gasp!) computer mode includes current depth, dive time, "no-stop"/NDL time, CNS O₂%/ascent rate and max depth, plus the little N2 loading bar graph over on the right. So everything you need on one screen and then some.

What I'd do if I were you (in fact, what I did) is to run your computer in computer mode (MB level set to L0 or L1) before you take the class, but instead of diving to the NDL number follow your depth/time to your dive plan. After several dives you'll begin to get a feel for the fact that diving your plan with an EAN32 table is conservative compared to what the computer will generate as an NDL for a multi-level dive. Confidence inspiring, IMO. I also found the variable ascent rate alarm on the Tec2G to be very enlightening , YMMV.

Plus, once you do get that puppy in gauge mode you'll get the stopwatch display that replaces the "no stop"/NDL number on the primary display, and switchable max. depth/avg. depth (resettable, OBTW).

FWIW, the Tec2G also has a reset function if needed -- in the menus instead of being a button, virtually every setting that is hard coded in other dive computers is user configurable in the Tec2G.

Lots to like about this computer/gauge, IMO.

John_B

 

[RTodd]

If I were you I'd just get the Tec2G and be done with it.

, but instead of diving to the NDL number follow your depth/time to your dive plan. After several dives you'll begin to get a feel for the fact that diving your plan with an EAN32 table is conservative compared to what the computer will generate as an NDL for a multi-level dive.
John_B

I can bend a 2G on the first recreational dive if I tried and generally would on the second. They are still too conservative. I can run one or two ML options in deco planner and have far more options than a computer will give me. Have someone teach you how to do multi-level dives and understand the benefits of being able to see your average depth to make "tweaks" on the fly.

Put it in gauge mode from the start and learn to do this stuff. The computer is a decent learning crutch but most people lean on it too much and for too long.

 

[Reg Braithwaite]

Never mind.

 

[Reg Braithwaite]

never mind.

 

[Gombessa]

A computer only diver wouldn't have the first clue of how to dive that profile safely without his shiny trinket on his arm and would have had to scrub the dive.

To wit: California Diving News - Opinions : Editorials - The Rules Apply to Everybody

 

[Reg Braithwaite]

To wit: California Diving News - Opinions : Editorials - The Rules Apply to Everybody

That's a really interesting article, but there are definitely two ways to interpret what he is saying. One way is that since the computer told him he couldn't dive for 24 hours, he meekly sat the day out.

The other is that although he knew that the risk of getting bent if he used his brain instead of the computer was insignificantly low, he has decided that the benefit of following the standard rules every time outweighs the benefit of exercising his personal choice to violate them from time to time.

Remember, in this case he has started with the choice to use a computer for a certain dive trip. So he followed through and stuck to his choice. I think this is entirely reasonable. It's also reasonable to decide you don't want to sit out a day if your computer craps out. In that case, isn't it (I suggest with temerity) a DIR principle not to dive the computer in the first place?

It seems to me that choosing to dive according to a computer's rules but then disregarding them when it will cost you a dive is neither fish not fowl: you aren't being a Thinking Diver, but you aren't playing it safe either.

 

[MXGratefulDiver]

Jumping in with both inexperienced feet, I do recall this one time I was on my fourth consecutive dive one Saturday... And a "reverse profile" was definitely involved since I did a morning two-tank charter and an afternoon two-tank charter, and the sequence went medium, shallow, lunch, deep, deeper.

Any ways, on dive four I was paying careful attention to the NDL on my Suunto Gecko and started to ascend with a few minutes to spare.

I stopped half way up to do a single deep stop and it went into deco! We discussed the matter in another SB forum, and one of the conclusions was that I shouldn't have been so close to the edge of its algorithm. But another conclusion was that its model simply doesn't allow for deep stops, it assumes I was continuing to on-gas and penalized me by demanding that I do another deco stop on my way up after that on my way to the "safety stop."

So, without saying whether somebody else should or shouldn't be bending computers, I can appreciate how a dive plan that may fit one model of deco may break another.

Not quite right ... RGBM does indeed consider the benefit of deep stops. In fact, NAUI is (to my knowledge) the first major training agency to endorse deep stops, even for recreational dives ... and Bruce Weinke (the "father of RGBM") is very instrumental in NAUI policies.

RGBM is built around a few basic rules ... one of which is "no reverse profiles". You violated that rule, and the computer penalized you accordingly. I cannot explain the delay in that penalty showing up in your NDL, because Suunto uses what they call a "modified RGBM" algorithm, and I do not know the specifics of how it works.

... Bob (Grateful Diver)

 

[rjack321]

RGBM is built around a few basic rules ... one of which is "no reverse profiles". You violated that rule, and the computer penalized you accordingly. I cannot explain the delay in that penalty showing up in your NDL, because Suunto uses what they call a "modified RGBM" algorithm, and I do not know the specifics of how it works.

Its my understanding that Suunto bought the name but not the actual algorithm. "Modified RGBM" is really gradient factor Buhlmann with some additional conservatism layered on.