Suunto Eon Steel And Its Algorithm Lock Logic.

[Pawlu]

I have been doing some research on the Eon Steel with an interest in potentially investing in what appears to be a well designed and thought out unit, I am also interested and quite confident in the advances made in the RGBM algorithm especially the fused RGBM as found on the Eon Steel. However I have one burning question regarding the algorithm lock and would really like Suunto's designers to clearly explain their logic in coding an algorithm lock in the unit.

In my quest to try and find an answer I hit Suunto's Eon Steel support page and found a similar question as follows:
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"Hi,
I just participated into a vivid facebook conversation about Suunto Eon Steel.
A group of divers apparently tec-divers were doing a deco dive. They had "forgotten" to switch gas on EON Steele. After a while, EON steel went into showing error on the screen.

They compared this to Petrel for instance, and told that Petrel would in that scenario just continue to calculate decos based on the scenario at hand rather than show "Error" message.

The divers discussed and wanted to know reason why Suunto has implemented it like this (error + gauge)? instead of adopting to the new situation and calculating the deco's based on that. "
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This question is yet to be answered, I posted a follow up response request to the above question (still to be reviewed by Suunto and displayed) as well as contacted Suunto technical support, however I was not given an answer to this incredibly important question.

Ok so according to the technical manual of the Eon Steel http://ns.suunto.com/Manuals/EONSteel/Userguides/Suunto_EONSteel_UserGuide_EN.pdf on page 20 the unit will behave as follows.

If you miss a deco stop by >2 feet an Error is shown on the screen advising you to descend back within the deco zone. If you do not correct this "Error" within 3 min the unit will lock leaving you with a very expensive bottom timer.

Okay, before going further let me begin by highly advising Suunto to replace the word "Error" with the word "Warning". An Error for all intent an purposes in a computing device signifies an incorrect input or output, ascending above a deco ceiling or missing a gas switch does not fall into either category. The word "Error" is totally misleading and a poor choice of words.

Furthermore and even more baffling is the fact that highly sophisticated unit, and one marketed towards technical or technically inclined divers will reduce itself to a bottom timer simply by violating a ceiling within 2 feet, whether due to an emergency or simply end user ignorance. I can think of an endless list of reasons why a diver might have to adjust their ascent profile on the fly that will result in them having to ascend to shallower depths with no ability to descend back to the original deco zone or zones. What is even more baffling is this statement right off the manual:

"Locking the algorithm is a safety feature,
highlighting that the algorithm information is no longer valid."

Can somebody explain how this is a safety feature? Why is it that an algorithm that is supposed to be dynamic and constantly adjusting ceiling and bottom zones based on the actual dive profile will shut down if a diver violates the recommended ascent profile, why cannot it re-calculate the dive profile and try its best to bring the diver to the surface from any new point assuming the diver has not shot straight up to the surface?

I am all for safety, and I have no issue with the unit locking itself AFTER the diver has violated the original recommended ascent profile for whatever reason, but not during a deco ascent!!!

I am really hoping to see some good reasoning behind this!

 

[Diving Dubai]

Hi @Pawlu

Firstly I have no connection with Suunto. My wife and I both have Eon's with around 150 dives each on them. If you want more info from an actual user with the good and bad points then please feel free to PM me.

Okay to your question. I'm not a technical diver, but have carried out planned deco dives with the Eon.

So you're correct if you bust the deco ceiling by 2' for 3 mins then it will lock out.

To be fair if someone can't hold their deco ceiling they shouldn't be doing deco dives.


This only applies to deco stops, not deep stops or safety stops.

I do agree it would be better it getting you to the surface before locking, I'm sure this is self protection from litigation.

I've seen other computers display the word error for a lockout - again yes perhaps a different word

All in all though I'm very happy with ours - we dive them with multiple transmitters (maybe 3 gasses) but for pure tech then I guess the shearwater is better

 

[Pawlu]

Hi @Diving Dubai

Thanks for your feedback, I might just take you up on your offer for more info. I guess the reality and simple solution to the issue of the unit locking out is to have backup wet notes or slate notes, (assuming any other Suunto dive computer would result in a lockout). Agreed if somebody cannot hold their position in the water within 2 feet they should not be attempting any deco dives, but there are a many valid reasons mostly due to unforeseen circumstances where a diver might have to ascend to a different depth and carry on to the best of their abilities their deco. Penalizing at this point does not contribute to safety, one must factor in the state of mind of a diver who for legitimate reasons had to change their ascent plan. Having a locking up computer will not help with stress and current anxiety. If the reason for this is for self protection from litigation then so be it, but even that reasoning does not make much sense. The computer can clearly record the fact that the ascent path taken was unsafe and not recommended (devices best effort to get you out of that situation.) I am not a lawyer but it would be easier to litigate from the consumers perspective the fact that the unit locked out vs the unit having to recalculate a best effort ascent profile...

 

[teknitroxdiver]

It seems totally unacceptable to me for a computer to just throw it's hands up and stomp off if you deviate from its deco plan. The Shearwater products will stay with you all the way, even if you do forget to do the gas switch or have to blow a stop for some reason (it happens, and if you're ever in that situation it would sure be nice to have your computer still helping you to deal with the change in plans). It's also, what, $500 cheaper?

 

[DuboisP]

Suunto computers are for divers not knowing what they need to know.
Divers knowing know how to manage their Suunto and/or purchase Shearwater, OSTC, and so on.

 

[tbone1004]

why are you OK with it locking you out after a safety violation? what if you have to get back in the water after an emergency for in water recompression? No reason a technical computer should ever lock a diver out, go to a real computer that won't lock you out under any circumstances... Better yet, for you, support a local Canadian business and buy a Shearwater....

 

[Pawlu]

# tbone1004 I did not say I was ok with it locking out after a safety violation. I said I was fine if it wanted to restrict further diving after violating a deco stop after the dive is complete. If I did blow through a deco stop I would not be in any hurry to get back in the water. Having said that however I do not want this post to be a Suunto bashing post. I have no issue with their products or advancement of the RGBM, the choice of purchasing a diver computer should really be based not on price or functions specifically but on ones comfort with its features, understanding of its algorithm and the style of diving planned now and in the future. My only issue is Suunto's logic with the lockout, this is standard with all their computers from entry level to their flagship product. If I was into any serious tech diving (what defines this I guess is anyone's guess) but for me it is depths >150 feet or deco obligations >20 min. than I would probably not purchase a Suunto product simply because of the lockout function. However with that being said that, any dives with deco obligations should really be backed up with some form of wet notes, documenting extended times at the next safest stop in case of issues.

Again as opposed to Suunto bashing I would really like to see somebody with some say in Suunto products to come forward with an answer or reasoning behind this design.

 

[teknitroxdiver]

# tbone1004 I did not say I was ok with it locking out after a safety violation. I said I was fine if it wanted to restrict further diving after violating a deco stop after the dive is complete. If I did blow through a deco stop I would not be in any hurry to get back in the water. Having said that however I do not want this post to be a Suunto bashing post. I have no issue with their products or advancement of the RGBM, the choice of purchasing a diver computer should really be based not on price or functions specifically but on ones comfort with its features, understanding of its algorithm and the style of diving planned now and in the future. My only issue is Suunto's logic with the lockout, this is standard with all their computers from entry level to their flagship product. If I was into any serious tech diving (what defines this I guess is anyone's guess) but for me it is depths >150 feet or deco obligations >20 min. than I would probably not purchase a Suunto product simply because of the lockout function. However with that being said that, any dives with deco obligations should really be backed up with some form of wet notes, documenting extended times at the next safest stop in case of issues.

Again as opposed to Suunto bashing I would really like to see somebody with some say in Suunto products to come forward with an answer or reasoning behind this design.

That's not how it works, though. As your quote from the manual points out, it locks itself immediately. I don't think anyone is 'bashing' Suunto here, just having a frank discussion on the very real shortcomings of their deco methodology.

As for backup tables, of course you carry them, but in many cases they're only a rough guide, especially if you're doing a dive that's not a square profile, like a cave. And you can only carry so many variations. A real deco computer will keep you a lot further away from having to start improvising by continuing to function as long as possible.

 

[Pawlu]

I fully understand how the unit works, and I am fully aware that it will lockout if violating a deco stop by more than 2 feet for more than 3 min. What I meant by my previous statement was that I would be fine if it wanted to penalize you after such actions after you ascended, such a function would promote safety. I understand that this is not what it does and it does in fact lock the algo out and go into gauge mode if violating mandatory stops beyond its pre defined threshold. I also understand that such a lockout only happens in deco diving.

What I am hoping to stir up here is some good reasoning behind this logic, I am sure there are hundreds if not thousands of consumers out there that would like a good reasoned answer to this, or maybe I am the one who simply does not get it. I do not think that Suunto purposely tries to limit its market by leaving such a function in a computer designed for the technical or technically inclined diver. Comments such as it is "not a tech computer" or "buy a real computer" or " divers no knowing what they need to know" do not really contribute to a reasoned answer.

The computer has a lot of testing and science behind it, tested by 100's of divers, backed by some big names and uses modern variants of the RGBM that promote safety. It is also very intuitive and easy to use. The only reasoning I can think of is due to the very nature of the Algo itself, that is focused on bubble size reduction vs dissolved gas pressure. One can argue that if the whole point of the algorithm is to prevent microbubbles exceeding in size and numbers, than performing an action that constitutes to increased bubble formation puts the algorithm in a null and void state.

 

[tbone1004]

you want the reasoning? they don't want to get sued. So why do you spend 2x as much on the eon vs a petrel or perdix.... What does it give you?

Who is using rgbm for serious decompression dives? I'm not aware of anyone...