[Dive computer] buying advice

[stuartv]

I would still dive this computer now if I hadn't had to go the other route and buy a second computer that was considered conservative.

I don't mean this as an attack at all. I know you are savvy about these things. So I am just curious what drove the determination that you had to buy a "conservative" computer, versus increasing the Conservatism Factor setting on the computer you already had?

I've read other posts from you. I know you've determined that you do actually need to dive more conservatively than the average bear. I would just like to understand "need a more conservative computer" versus "increase CF on existing computer". I have said many times that "you can make a liberal computer conservative, but you can't make a conservative computer liberal." Of course, the implication (which I have believed) is that a liberal computer with an increased CF setting would be just as "good" as a computer that is natively conservative. If that's not true, I'd like to know it, so I can stop promoting that idea!

 

[uncfnp]

Hi stuartv. Not seen as an attack at all just another story and viewpoint. My computer was enty level. No extras and no conservative factor settings. It was straight DSAT. It was a lot to deal with for a relative new and naive diver. And while I know enough to do it now, make all my own adjustments, remember it's not just about shorter dives. For me, conservative diving is a multifactorial issue that includes ascent rates, surface intervals, bottom times and gas. And even though I know and manage these factors as well as my human brain can I still like the hard numbers the computer will spit out, and adjust for any oops I may have made during the dive, a little deeper, more sawtooth, etc.

The other option that was recommened to me was dive nitrox on air settings, but that didn't sit well with me. So I started my algorithm search.

And because not all the factors are known, including proprietary algorithms and personal factors, it's still a lot of trial and error. I bought the Cressi specifically for the RGBM and did well so bought a third computer to see if I could fudge a little, a Geo 2.0 and even on conservative settings I had problems and sold it. When I started cave I bought the Petrel 2 and set at 30/70. Didn't work. I have had my most success thus far with the Cressi on SF0 and Petrel on VBM 5 and deco on 02 when diving "local" with my own tanks. But tomorrow's another day and there may be more adjustments. I seem to be a human bubble machine.

 

[stuartv]

no conservative factor settings

I didn't even know they made them like that. Totally understand now. Thanks for the explanation.

 

[dmaziuk]

I didn't even know they made them like that. Totally understand now. Thanks for the explanation.

Wasn't it the one without uplink port and with factory-replaceable battery? Or was that the Aeris version? ISTR they were on closeouts back when I was shopping.

 

[Aqua-Andy]

This sub-forum is for "new divers and those considering diving" so I really don't see the point of mentioning trimix and multiple gases.
Incidentally I use trimix occasionally as well as deco gases for technical diving but never own anything other than basic nitrox computer or just plain bottom timer.

If I am in the market looking for a computer for recreational diving. It has to be:
1. Cheap
2. User replaceable battery
3. Nitrox compatible.

This is my view also. I just don't see the point of a new diver spending $1200 or more on a dive computer that they may never fully utilize. My personal favorite is the Hollis DG02 Digital Bottom Timer and Nitrox Computer | Dive Right In Scuba - Plainfield, IL - Dive Right in Scuba Name one thing that this computer can't do for a recretional diver. When and if you decide to get into tech diving it also has a bottom timer mode. One thing I will add to the quoted list of must haves is availability of a DSS boot so that it can be bungee mounted.

 

[ls1dreams]

Why don't you like Suunto? For a beginner, it's probably just fine.

I don't think it's fair to compare it to an Oceanic that $350 when you can find a Zoop (old style) for $160-$180 brand new at half the cost.

While I like the looks of the GEO 2.0, it offers very little over the zoop except for a backlight and dual algs.

 

[Diving Dubai]

except an Eon Steel (which runs a different algorithm than any other Suunto - RGBM Fusion versus other RGBM

A slight correction if I may

The Eon (and I believe teh DX) runs the Fused RGBM. As explained to my by Suunto in layman's terms, for Shallow dives this operates in a similar way to their normal RGBM, switching over to the Technical RGBM on deeper dives (apparently at 30m)

I have not had an opportunity to dive a Zoop or Nova alongside my Eon to verify. My Eon has 5 conservatism settings 0 being default and two settings either side (+1 & +2) for more conservative or (-1 & -2) less conservative. I suspect that I would need to change my settings to +1 to be similar to a Zoop/Nova on their default

There is very little objective data available on repetitive diving profiles and dive computers. I am not endorsing one algorithm over another, but do advocate that divers be aware of the decompression algorithms prior to their computer purchase. You can make liberal computer more conservative, there's nothing you can do to make a conservative computer more liberal.
http://ads.bonniercorp.com/scuba/PDF/ScubaLab-Computer-Test-September-2014-data.pdf

StuartV drew my attention to the latest review And there is a down loadable excel sheet I was surprised to see how close all the computers were. Stuart and I had some off line discussions and basically for a given plan my Eon could be more liberal than a Perdix on 90/90 and only slightly less than his Atom. This is splitting hairs because we were only talking a minute or so

Suunto computers will become conservative on repetitive dives if you have an SI of 1 hour or less. Personally I prefer a 75-90 minute SI, but I know some ops that want you back in the water asap. If this is the case, and you are going deep again (25-30m) then they will certainly limit you. If however you are on a decent SI, in my personal experience not so much

 

[dmaziuk]

Suunto computers will become conservative on repetitive dives if you have an SI of 1 hour or less. Personally I prefer a 75-90 minute SI, but I know some ops that want you back in the water asap. If this is the case, and you are going deep again (25-30m) then they will certainly limit you.

You'd have to keep in mind though that on a typical boat schedule 1 hour SI happens with the 2 tanks before lunch. Then you have a lunch break with 1.5-2 hours SI, and so far I've not seen 2 tanks after lunch offered. You really need to be someplace that's "all you can dive" and is relatively deep at that: e.g. on Bonaire you can easily finish your dives in the shallows with your computer crediting that towards off- rather than on-gassing. (Bubble models tend to imply that off-gassing is more efficient at safety stop depth than at the surface.) Liveaboards would be one example I guess.

 

[scubadada]

You'd have to keep in mind though that on a typical boat schedule 1 hour SI happens with the 2 tanks before lunch. Then you have a lunch break with 1.5-2 hours SI, and so far I've not seen 2 tanks after lunch offered. You really need to be someplace that's "all you can dive" and is relatively deep at that: e.g. on Bonaire you can easily finish your dives in the shallows with your computer crediting that towards off- rather than on-gassing. (Bubble models tend to imply that off-gassing is more efficient at safety stop depth than at the surface.) Liveaboards would be one example I guess.

The usual schedule is dependent on where you dive. In SE FL, AM 2 tank dives often have SIs of 45-60 minutes. The lunch break is generally about 2 hours, and many operators have a PM 2 tank trip that is run similar to the morning. My experience on LOBs is that the SIs are generally longer, in excess of an hour. You do have all day, starting early, to get in your 4 dives, or 5 with a night dive.

 

[Diving Dubai]

I do have a nagging question, which I'll throw ope, but will also direct at @scubadada & @stuartv

Cold water diving - completely alien to me as you know:

I was taught (and it came up in my DM theory) That for cold water diving, using the PADI RDP, you add 10' to your max depth for added conservatism.

Is this still considered normal practice?

How do people do this on a computer? Do they increase the conservatism by 1 step, or just dive the NDL with no modification?

I'm always assumed that that dive computers don't use the temperature in their calculations (but happy to be corrected)