Shearwater Petrel 2 vs. SubGravity H3

[DevonDiver]

As a technical diver/instructor, what I value most about the Petrel is choice; the ability to designate my own preferences, both in advance and/or change parameters 'on the fly'.

CHOICE

1. Algorithm: Petrel offers choice, via firmware upgrades, on user selected algorithm. Algorithm choice matters to me.

2. Display: Petrel offers choice, via set-up menu, on user preferences as to what is displayed, where and when. There are many options. I value the 'ceiling' and '+5' options, in particular.Do the H3/T1 offer flexibility and choice like this?

FLEXIBILITY

It was lack of flexibility that killed the VR3. A model must re-calculate if demanded. I'm assuming the H3/T1 does this. But how about re-defining conservatism 'on-the-fly'? The Petrel conservatism can be changed in-water. It recalculates accordingly. This gives the option to react to variables that occur during the dive: a quicker (riskier) abort profile, or a more conservative ascent should it be demanded (i.e. unforeseen factors arising; such as more exertion than anticipated).

RELIABILITY

It was reliability that killed the Liquivision X1. Rechargeable batteries get a noxious reputation... especially if you're trusting your life or health to them. Batteries may not charge, or charge fully. Rechargeable battery performance declines over time/use. Rechargeable batteries are expensive to replace.I don't see rechargeable batteries as a bonus point. I value the K.I.S.S. approach of user-replaceable batteries, which are globally available 24/7 from every 7/11. It was precisely this that initially won my loyalty from Liquivision to Shearwater.

USER-INTERFACE

I've not had chance to play with an H3/T1, but I am concerned about the risk of 'accidental' manipulation of the 'wheel'. My hands/arms can get busy on dives, they can rub against things, stuff gets knocked and moved around. I'd be concerned that the wheel could more easily get bumped into 'settings' during the dive - causing potentially catastrophic amendments to the dive calculation.

FEATURES

For technical diving, I don't care about AI, transmitters, compass, facebook integration etc. I just don't. I want something 100% reliable, that gives me the information *I* want, when I want it and how I want it. That information is all about conducting a safe technical dive, under parameters I designate, based on years of experience and intimate knowledge of the way *I* elect to plan and conduct dives. I want a computer that supports me in that.

For recreational diving, I am far too practical and budgeted to spend $$$ on anything more than what I need. I still use my original, aged, 1st release, Vyper for this... it gives me three things... depth, time and NDL. It's all I need. So I really cannot comment on the attractiveness of an H3/T1 for the recreational diver. I don't understand why people buy iPhones either, if they're only gonna trawl Facebook and text/call on it.

A tech computer isn't a 'premium purchase' luxury item for technical divers. It's a necessity. It fulfills a need. It should concentrate on fulfilling those needs... and by acknowledging that tech divers have varied needs.... it should give them the flexibility to set their own parameters for it's functionality.

 

[stuartv]

For recreational diving, I am far too practical and budgeted to spend $$$ on anything more than what I need. I still use my original, aged, 1st release, Vyper for this

This statement underpins the original draw I felt to get an H3. You have 2 computers - one for tech and one for rec. I am facing that. My thought was "why not just get an H3 and use it for both and save some money?" The H3 form factor and AI option would make it a very nice replacement for my current rec wristwatch computer with AI. And then I could also use it for tech diving. One computer to buy instead of two sounds like a good idea.

But, the more I've let that roll around in my head, the more times I hear my own voice echoing that it is better to always dive with 2 computers. And if I'm going to have 2 computers, at least for doing tech dives, why not just keep my current wrist computer for use in gauge mode on tech dives? And then get a Petrel for use only on tech dives (or maybe also carry it as a backup on rec dives - it won't give as long NDL times as my Rec computer, but that's okay when I'm using it as a backup).

I could get the H3 and still keep my current computer as backup in gauge mode (for tech dives). But, part of the appeal of the H3 is having that form factor for Rec dives - e.g. not having the Petrel brick on my arm during warm, clear Caribbean dives. If I keep my current wristwatch computer, I don't need the H3 for those rec dives. At which point, being able to replace the battery in my tech computer myself and use it forever, with no significant maintenance expense (just AA batteries and that's it) and no matter what happens with the manufacturer, starts weighing more heavily in my mind.....

 

[rhwestfall]

[video=youtube;kxig2AF1-gw]https://www.youtube.com/watch?v=kxig2AF1-gw[/video]

 

[Dhboner]

If you are doing a "tech" dive and relying on your computer (you haven't cut tables) then, IMHO, both your primary and back-up computer should run on the same algorithm. If you dive a Petrel and want a back-up computer for "tech" dives get another Petrel. If that isn't in the budget use a bottom timer as a back up and make sure you have tables with you.

 

[rhwestfall]

I "need" VPM-B w/GF, choice thus easily made.....

(team decision to utilize the VPM algorithm)