looking for my first dive comp

[dmaziuk]

Hi! The suunto vyper here costs about the same as the oceanic and sherwood. Would you recommend i buy from an authorized dealer abroad where it will most probably cheaper? Would i have any problem along the way? The only issue with oceanic here in the Philippines is the slow requisition of parts in case something breaks down. I saw the sherwood online for $260 though.

They don't break often as far as I know so I woudn't be too worried about that.

Vypers seem fairly popular but personally I don't believe they offer any real advantages over $150 Mares Puck at this point. The other 2 computers you asked about are watch-sized, that typically comes with higher price, but with the vyper you're pretty much paying extra for the brand name.

 

[runsongas]

the vyper is popular as it has gauge mode and includes the usb cable compared to the zoop. still more expensive than the puck, but some people hate one button computers.

 

[ScubaJill]

What I learned so far is the longer you stay down below, the more gas gets into your tissues. The more gas you have in your tissues, the longer it takes to off-gas. The difference between NDL and Y(es)DL is

• NDL: you can slowly swim up all the way, but you really really should make an optional but highly recommended safety stop, and have a one in bazillion trillion chance of getting DCS.
• YDL: you can slowly swim up, but you must make a non-optional deco stop in order to keep your chances of getting DCS down to the same one in bazillion trillion.

To me it looks like the key in both cases is having enough gas for the stop. I would think, the chances of having enough gas for the stop would be better had one actually planned for it in the first place.

Aside from that, the way computers work is they periodically recalculate stuff. If you come up to depth X and see 2 minutes NDL: wait a few seconds and 2 may change to 99. If you come down to depth X and see 2 minutes, then you have a choice of staying down for 119 seconds or "blowing past" NDL and making your safety stop mandatory instead of optional. If you stay long enough at shallower depth after blowing the NDL, you may well find your mandatory deco obligation has magically disappeared from your computer screen.Etfc.

But like I said, that's just me -- if your definition of "better computer" includes bigger NDL numbers, that's NMP.

Thanks, dmaziuk. This is a good way to frame the issue.

 

[dmaziuk]

the vyper is popular as it has gauge mode and includes the usb cable compared to the zoop.

Ah! I stand corrected: the cables are around $100 (puck is an exception) so at $260 with cable, vyper is definitely a contender. Unless you're really determined to never ever keep your dive log on your PC and so will never need the cable.

 

[Tbar]

I have rarely been limited by my buddy getting low on air.

I have never had to end a dive because of hitting an operator's time limit. Operators in the Outer Banks don't give a time limit that I'm aware of and the operators I've gone out with in Hawaii were chosen, in part, because they specifically allow their customers to dive their tank - even the ones like me that rent a 100 or a 120.

I have done a number of dives (of my limited number, total) where I was able to stay down until the NDL of my liberal computer - and my buddy with me. I HAVE had to end dives earlier than my computer required because my buddy had a Cressi computer that gave a shorter NDL.

Your liveaboard experience suggests that maybe your dives tended to have average depths closer to maybe 60 feet or less, where NDLs are longer and an AL80 also lasts longer. Some people (me, for example) more normally do dives in the 100+ foot range where NDLs are short, even on Nitrox, and it's not that hard for even a plus-sized man like myself to outlast the NDL, even on a liberal computer - especially if using any size tank that is larger than an 80.

Please - your original post said "diving a typical reef profile". My response was 21 dives on reefs and they are what I see as a typical range of dives having done a number of multi-day liveaboards on reefs, some of the dives were around 35m (120ft), some only 8m (30ft).

If the dive operator does not provide a max dive time then I would question the operation. 1, this allows them to keep a schedule 2, it ensures that they can enact safety procedures quickly if a diver does not return - if you have no max time how long do you wait until you believe you have an issue? (that's a rhetoric question)

 

[Nicole Chan]

Hi Nicole,

The Sherwood Amphos runs the DSAT decompression algorithm, basis for the PADI RDP. The Oceanic Geo 2 runs DSAT and PZ+, a proprietary version of Buhlmann ZHL-16C, somewhat more conservative than DSAT. I dive a Geo 2 as a backup to my VT3, running DSAT.

Mares , Suunto, and Cressi all run proprietary versions of RGBM decompression algorithm and are generally more conservative. Mares and Suunto appear to run similar to PZ+, Cressi is the most conservative of the group. Many divers prefer a more liberal algorithm, particularly when their initial air consumption improves to the point where NDL makes a difference compared to air consumption. I believe dmaziuk dives a Cressi, his air consumption must make NDL less of a consideration. This debate has been played out in numerous computer threads on SB

If I were you, I would go with the Geo 2.

Best of luck, good diving,

Craig

Hi Craig! Why do you recommend the Geo 2? What features does it have that make you love it?

 

[scubadada]

Hi Craig! Why do you recommend the Geo 2? What features does it have that make you love it?

Hi Nicole,

I don't love the Geo 2, it's not emotional. I recommend the Geo 2 for a variety of reasons. I have 613 dives and 644 hours of diving on my Geo 2 as a backup to my VT3 since Sept 2011. It has been 100% reliable and the battery changes are quick and simple. It is very easy to read, especially for a watch design. It is as easy to read as my puck style VT3.

Personally, I would not dive any of the proprietary RGBM decompression model computers (Suunto, Mares, especially Cressi) as they are much too conservative for me and my diving. The exception might be the Atomic Aquatics RGBM, it compares favorably with DSAT but is not available in a wrist computer, to date. I dive the Geo 2 in DSAT, though I appreciate the dual algorithm and the option of PZ+. My VT3 is pre-dual algorithm and runs just DSAT. I have over 1,100 dives on DSAT since 2002 and am very familiar with it's performance.

Eventually, I will buy a computer running Bulhmann ZHL-16C with gradient factors, but not until one offers air integration. My current configuration is an AI VT3 with the Geo 2 and a SPG as backup (not needed to date).

Good luck in your computer purchase. Obviously, there are all kinds of alternative recommendations available to you here on SB.

Good diving, Craig

 

[Nicole Chan]

Hi Nicole,

I don't love the Geo 2, it's not emotional. I recommend the Geo 2 for a variety of reasons. I have 613 dives and 644 hours of diving on my Geo 2 as a backup to my VT3 since Sept 2011. It has been 100% reliable and the battery changes are quick and simple. It is very easy to read, especially for a watch design. It is as easy to read as my puck style VT3.

Personally, I would not dive any of the proprietary RGBM decompression model computers (Suunto, Mares, especially Cressi) as they are much too conservative for me and my diving. The exception might be the Atomic Aquatics RGBM, it compares favorably with DSAT but is not available in a wrist computer, to date. I dive the Geo 2 in DSAT, though I appreciate the dual algorithm and the option of PZ+. My VT3 is pre-dual algorithm and runs just DSAT. I have over 1,100 dives on DSAT since 2002 and am very familiar with it's performance.

Eventually, I will buy a computer running Bulhmann ZHL-16C with gradient factors, but not until one offers air integration. My current configuration is an AI VT3 with the Geo 2 and a SPG as backup (not needed to date).

Good luck in your computer purchase. Obviously, there are all kinds of alternative recommendations available to you here on SB.

Good diving, Craig

do you do tech diving? is that something i should consider or will that take a long time for me to worry about now?

 

[scubadada]

do you do tech diving? is that something i should consider or will that take a long time for me to worry about now?

Hi Nicole,

No, I do not do technical diving. The Geo 2 would not be appropriate for technical diving though it does offer a gauge mode, which would be useful in some situations. Nearly all my dives are within recreation limits. I occasionally dive deeper than 130 feet and a little less than 5% of my dives have some very light deco, less than 15 minutes, average 5 minutes. The VT3 and Geo2 are fine at this time for my diving.

Only you know if technical diving is in your future and when. It's often better for newer divers to get a good basic computer to use while they are accumulating experience and then buy a high quality technical computer when and if that is indicated. It is also likely that there will be improvements and options available in the future to influence decisions

Best of luck, good diving, Craig

 

[Macan]

do you do tech diving? is that something i should consider or will that take a long time for me to worry about now?

See link below

A sense of algorithm

Also sent you a message.