Tec computer with Trimix and A.I., is Suunto HelO2 the cheapest option?

[rhwestfall]

there is one (might even be an A/I version too) that will work out solutions all the way until you surface, but there are significant haters around here of it.....

(I'm not at all saying that you should be doing any diving where you rely only on the "magic bracelet", and I don't like A/I)

 

[boulderjohn]

I don't see any dive computer mfg assuming that kind of risk. There is however a computer that will do all of that. It is the one.between your ears. You set parameters for what you just described, plug them into v planner or other software and write down or print out the results. Then when the crap does hit the fan you pull them out and using your bottom timer follow.that plan. Once you start tech training you'll see, at least in my experience and with the instructors I would take further training from, whatever computer you get is going to be used in gauge mode with printed tables anyway. Even if you could find a computer to do what you want what do you think you'll fall back to on a dive if it craps out.
I dive a shearwater predator with vpmb unlocked. I still would never do a tech level dive, or most recreational deep dives, without written back up to follow on my bottom timer.

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That written backup plan only works if you are reasonably close to your plan. I do the same thing, but my written plan is not much good if I run into something that really causes a problem, such as what happened in Norway when divers got trapped in a restriction and their buddies spent a very long time trying to free them. "Plan your dive and dive your plan" sounds great, but sometimes things happen. A siltout in a cave can delay your exit significantly, as can a lost buddy. Look at what happened with Bill Gavin and Parker Turner--two great divers who got into a mess beyond their control. A couple of months ago a very experienced diver in the Jailhouse Cenote took a wrong turn and went quite a ways before realizing it--he almost made it back to the exit.

 

[kr2y5]

whatever computer you get is going to be used in gauge mode with printed tables anyway.

Yes, for now, for the sake of training, I have just ordered a plain bottom timer to use with pre-planned deco schedules... but my impression reading replies in this thread was that many tech divers would not object to carrying a full computer, and while at it, one that never quits on them and produces usable deco schedules in all circumstances... and I might want to do so as well...

I don't see any dive computer mfg assuming that kind of risk.

...and it sounds like Petrel, among a few others, is such a computer: it never locks up, and always proposes some deco schedule. Out of a pure intellectual curiosity, what is the formal basis for proposing a deco schedule, if not the strategy that I outlined in the previous post? Earlier in the thread, some postulated that once you violate a ceiling or ascend too fast for sufficiently long, "bubbles have already grown", and there's nothing more that a computer can do besides displaying ERROR anyway, since the likelihood of DCS is already outside the range that the underlying model was designed for. Others proposed (and I'd agree) that a tech computer should still try to calculate a deco schedule in such a scenario, and pointed out that it is in fact what Petrel does, despite the fact that we're already dealing with an increased risk of DCS. So clearly, some brands of computers do attempt at calculating deco schedules in any circumstances despite the increased risk. Or am I misinterpreting something?

 

[Liquivision]

First of all many people don't understand that if you miss a deco stop, there is still a HUGE advantage to descend again to the depth you missed. Freedivers do bend-and-mend all the time, they ascend rapidly straight to the surface, produce lots of bubbles, then immediately descend again on compressed air, and if they don't re-descend, they can (and often do) get seriously bent. Descending again shrinks the bubbles and the N2 can re-absorb into the blood.

Secondly, if you decide NOT to go back down after missing a stop, yes you produced some bubbles, the computer's job is now basically to do its best to prevent further bubbles from forming.

Eric Fattah
Liquivision Products

 

[Omisson]

Yeah I would avoid A.I., you'll come to find in tech we like things with the least probability to fail. If you are relying on an AI computer, if your computer fails you loose your gas pressure as well.
My recommendation is to do your training first and then look at shopping. That's what I did and I'm so glad I did. I have a Shearwater Predator for my Hollis Prism 2 and I love it! Shearwater is amazing, cant beat the display, simplicity and algorithm. But I recall Hollis just released a new TMX computer (also AI coincidentally).

Well...... Let me start by saying the rule in Tec is redundancy. Having a mechanical spg and an AI is redundancy.


Hollis TX1 is a rich 16 tissue compartment algorithm AND has AI ...

Just sayin...


Dan-O

 

[KenGordon]

F

Secondly, if you decide NOT to go back down after missing a stop, yes you produced some bubbles, the computer's job is now basically to do its best to prevent further bubbles from forming.

Eric Fattah
Liquivision Products

At the risk of you telling me to RTFM how do your products handle users going above the ceiling for a time? For example if I am at 6m for 10 minutes when the ceiling was 12 to 10m (assuming it continues to reduce while I am above it).

What happens when you get out of the water with stops still due, if you get back in will it try to give you an appropriate schedule?

Personally I don't really care about these user induced error modes. They are very unlikely. What annoys me about the HeO2 is:

Accidentally engage gauge mode while dry and you have to wait a couple of days to use it as a computer again. No are you sure or 'I have not been wet so ok...'

The DM4 planning software leaves a lot to be desired when trying to plan a multi gas dive for transfer to a slate.

It seems that the available adjustments on how conservative the deco model is are too restrictive. Particularly on helium.

Having said that, for a particular dive it is often quite close to VPM-B or GF cut tables as they assume a square profile and so there is often significant extra conservatism due to the actual profile shape. Maybe computers ought to be rather more conservative than planning tools for this reason - but it really messes with the gas planning when you try to do it for a square profile AND strict conservatism.

I can see where Suunto are coming from with the error modes and conservative models - they are mass market with many users who have been told that any deco is a terrible thing and who have no idea what to expect. They are robust, work for years (what did the OP do to that poor Zoop to kill it in 80 dives?) and mostly just work.

I am vaguely in the market for more sophisticated computer, so I am interested in what Eric has to say, although I suspect I will be buying one that comes with a big yellow box attached.

Ken



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[kr2y5]

First of all many people don't understand that if you miss a deco stop, there is still a HUGE advantage to descend again to the depth you missed. Freedivers do bend-and-mend all the time,

This brings up a question that has always been stuck in my mind, and for which I have yet to see a good answer... what exactly is wrong with mild sawtooth profiles? How will Liquivision X1's algorithm handle such profiles, will you penalize a diver, and why? Assuming here that the ascent part of a sawtooth obeys a safe, conservative ascent rate (not talking here about bouncing back and forth between 20 and 100 feet), the following descent part of the sawtooth should cause any microbubbles formed to re-compress. What is the exact nature of the residual "badness" following a temporary ascent and redescent?