Question about dive computers

[Stormblessed]

OPs question has already been answered, but I would like to add this...

Buy what you need right NOW, not for what you might need later. (future “proof”) Because when the day comes that you need more from your dive computer, chances are there will be newer and better models on the market.

I did not heed my own advice here, I bought the Shearwater Teric, but, I bought it becaues of the clarity of the screen.

This should be the only exception to my advice imo, you gotta be able to clearly see what’s going on, preferable with just a quick glance, and if that means a more expensive dive computer then so be it.

The teric looks absolutely amazing though. I know I don't need it but it is just sooo tempting

 

[Jay]

I said "most common". Yes, you and Stuart, and who else?

I'll join in

The teric looks absolutely amazing though. I know I don't need it but it is just sooo tempting

It's stunning. It's very hard not to say no to (except when it comes time to pay for it ... Especially if it costs you double because your other half needs one too).

 

[rongoodman]

Its display is pretty amazing next to the Perdix or Petrel.

 

[KenGordon]

It's a) not going to give you an optimal decompression profile and b) I strongly suspect even DM5 won't let you plan a deco dive for a Zoop.

"Recreational" computers will get you topside you safe if you overstay your NDL. That is not quite the same thing as computer designed for planned decompression dives.

Of course DM5 will let you plan a dive for a Zoop. Dive planning is what it is for. Of course a Zoop will let you execute a planned deco dive.

Above are plans for a 44m 25 minute dive, such as the Markgraf SMS Markgraf | Scapa Flow Wrecks
Round here that is a pinnacle dive for the third season of a fairly keen club diver. There are three plans, the Zoop plan (3@9, 8@6, 23@3 (plus 3 SS) run time 67 minutes), a 50/80 plan (1@15, 3@12, 5@9, 8@6, 20@3 run time 66 minutes) and a 50/85 plan (1@15, 2@12, 4@9, 8@6, 17@3 run time 61 minutes). When using a GF computer I use 50/80.

(As an aside you will find SB experts warning of the terrible (ie now unfashionable) deep stops inserted by RGBM, and hence Suunto RGBM. It can be seen from the plan above that Suunto RGBM will give a shallower first stop than GF50/85 - or 80/80 indeed)

There is also an actual dive on that wreck on a Zoop (on 25%). It is quite tall and we will have bagged off from the top. I will have been using a Spiro BCD with independent twins and two a-clamp regulators.I have no idea how I lived to tell the tale.

A similar dive 10 or 20m deeper would really need a deco gas. Using a deco gas really needs a computer which can switch gases in the water. A Zoop will not do that but Aqualung have entry level computers which do, and Suunto have models which do so. They cost a bit more.

So for any dive which any recreational (meaning no stops) diver will do an entry level computer will work very well. And when they initially stretch themselves into deco diving it will still do so.

Maybe @scubadada can tell us how to plan this dive with an Oceanic computer.

I am pretty confident that there have been more Zoops visiting the guns on the Markgraf than Terics.

 

[Gareth J]

Nice post Ken

There are two noticeable things about this particular forum;

1. Suunto is seriously disliked, I don't really know why. Especially when you realise how many thousands of decompression dives are done off the UK coast using Suunto's. And, how popular they are world wide.

2. Being a predominantly American based forum, decompression diving is considered too dangerous for recreational divers. Despite it being a normal progression within the core diver training for a large number of divers in the rest of the world.

Gareth

 

[scubadada]

Hi Ken,

Right tool for the job. You're right, you cannot plan a deco dive for my Oceanic computers and DSAT was not developed for decompression diving. 95% of my dives are no stop, the other 5% are light deco, <10 min, average about 5 min at 10 ft. Of course I have my Nitek Q and also have MultiDeco, like you do.

Good diving, Craig

 

[scubadada]

Hi @Gareth J

I would choose a Suunto over Mares, Cressi, Scubapro, and Deepblu, just not the right computer for me. If I was doing serious decompression, I'm pretty sure I would be diving ZH-L16C with GF

 

[Gareth J]

On the computer issue.

It is relatively recently that computers running none proprietary software (e.g. standard Buhlmann) have become available.
The VR3 was probably the first, it ran a straight Buhlmann table, with pro planner being the dive planning software that preceded it.
Since then, the number of 'technical' computers available has steadily increased, with the established dive computer manufacturers producing their own as well (Suunto Eon Steel).

My early decompression diving used Suunto's first the EON, then the Vyper, then the Vytec. [1]
We used to plan on the basis of available gas times, turn pressures, tables, then modify based on what the computer was actually saying during the dive. As a precaution, we used to double the stop times. i.e dive computer gives 5 minutes stop, we would work on the basis that it was a 10 minute stop, and start the ascents accordingly. Even more amusingly, it was pre Nitrox, so everything was on air.
Later, we used to dive air, then decompress on Nitrox50, still running air profiles (that's all that most computers could deal with).
Eventually, I went back to tables (from pro-planner), and started accelerating the stops. Then the Vytec appeared. I almost bought a VR3. I switched to CCR, and a VR3 was the goto unit to plumb into the loop. I bought the vision, which had a built in dive computer, so my need for a VR3 ceased.

Gareth

[1] Interestingly Suunto appear to recycle their computer names over time.
The original EON was air integrated, single gas DC. The current Vyper spec is different to mine.

 

[drrich2]

1. Suunto is seriously disliked, I don't really know why.

Hoping not to veer off on the 'Suuntos are/aren't too conservative' tangent, here are 2 impressions I've gotten from the forum about them over time and various threads:

1.) Many people use them, they're obviously popular, they're widespread and have strong brand recognition.

2.) They (I'm talking Zoops & similar, not EON Steel) are seen as having more conservative algorithms that may (people debate this) give not really shorter/trivially shorter/a few minutes shorter/several minutes shorter NDLs, which can cut dives short unless you learn deco. procedures, which I think the large majority of U.S. divers never do, and it's fairly common in this region for a dive boat to forbid deco. diving. A lot of recreational diving is done in trips, often with 'insta-buddies' or a group. If your Suunto gives 10 minutes NDL, and your buddy's Oceanic gives 15, if you stay together, his dive got cut short 5 minutes (#'s made up to make a point).

I've also seen it claimed Suuntos tend to penalize sawtooth dive profiles, which aren't that uncommon, and it can affect repetitive diving. Then again, some people use Suuntos for multi-day repetitive diving.

The criticism toward Suuntos seems rooted in the idea they allegedly cut short NDL's a bit, more liberal computers give you more time and still seem acceptably 'safe' so the Suunto's conservatism is viewed as 'robbing' divers of NDL for no useful purpose. If there are other computer options with liberal algorithms that Suunto has no clear advantage over, why get a Suunto?

It's not that Suunto is bad, just that a competitor may be about 'as good,' give you a little more NDL on at least some of your dives without putting you at undue risk of decompression-related problems, so why not get the competitor?

There may be good reasons, and Suunto fans may want to list them.

The original poster is in Asia. I don't know his/her local market product availability, access to warranty servicing in case of problem, what most people diving the locale use, pricing, etc... In his/her local context, a Suunto might be the best choice.

Richard

 

[rongoodman]

The VR3 was probably the first, it ran a straight Buhlmann table, with pro planner being the dive planning software that preceded it.

The VR3 manual says otherwise:

"The VR3 uses a derivative of the Buhlmann ZHL16 algorithm. Exactly the same adaptation is used in Proplanner decompression software. The new versions of both systems employ some of the latest thinking in practical microbubble avoidance and compared to standard parallel compartment models may seem to modify the dive profile. This modification takes the form of deepwater microbubble controlling decompression stops."

The first computer I remember running unmodified Buhlmann GF was the Liquivision X1, following the release of MultiDeco. It initially ran VPM only.