Can Suuntos be adjusted to not be as conservative?

[The Laconic]

No, not if you understand deco theory and do not just rely on what a computer is telling you. It's never a good idea not understanding what your computer is telling you and just follow it's instructions.

As far as the computer goes: why would you want to dive with a computer you clearly don't rely on? That's really dangerous. The danger of not following/relying on computer instructions and not having thorough knowledge of deco theory to do the math yourself is a recipe for trouble.

Let me rephrase: you aren't changing your risk of DCS by doing something to your computer. You're just saying you accept a higher risk of DCS in exchange for increased bottom time. Which is your call, but don't pretend you're doing something else.

If you have to ask whether changing the pO2 is the right thing to do, you probably shouldn't be doing it. I'm not saying it's a good idea at all--I'm saying that if you're going to fudge your computer without really understanding what you're doing, you might as well just drop the charade and add a few minutes to whatever it says. (Exactly: why would you want to dive with a computer you clearly don't rely on?)

 

[RJP]

I dive with a Zoop. I noticed I had less bottom time than my buddies who I think all have Uwatec computers. I found a simulator for the Zoop as an add-in to a dive planner for the iPad. It helped me understand what to expect if I blew past my ndl and started to accrue ascent time. I learned how to plan for that extra time, found it accurately predicted how that ascent time would suddenly disappear if I ascended to about 30', and how many minutes beyond ndl really turned into an extended "deco" time.

Who needs one of those pesky deco courses, huh?

 

[KenGordon]

Yeah, so, again, Suuntos suck on subsequent dives. They suck for adding fudge factors arbitrarily. They suck for not being predictable. I'm not saying one mostly-square dive is bad on a Suunto. I'm not saying they're dangerous. I'm saying the algorithm sucks, and it being so opaque and arbitrary makes it suck even harder. I even said above:

My post had nothing about surface intervals or subsequent dives so I wonder about your use of the word 'again'.

Predictable? You can use the Suunto supplied software to predict the times for a series of dives. If this was not predictable how would I know how much time I could get for a given gas supply? If I had nothing better to do I might compare the NDL for a dive following yesterday's. Of course to do that for the petrel I have to spend more money to get an offline planner... Maybe you can do GF calcs in your head.

Just because YOU don't understand a thing does not make it arbitrary. I want my computer to take account of my mistakes on a dive. That is one advantage of them over tables. If I miss a deep stop, do repeated ascents or race up at high speed I'd like to be able to equalise my risk. I think a computer is better place to track my mistakes than I am as a task loaded person making them.

I once did an experiment with vplanner where I fed it a total seesaw profile. It seemed to make no difference to it at all. Did I think that was a good thing?

We are taught that multiple ascents are a risk factor. A quick Google does not reveal a primary source but I can't imagine who would be doing a study on it as only rec instructors and small scale fishermen are likely to suffer, no oil companies or navies involved.

Again I think that there is a tendency to look at NDL times as important. This seems to me to arise from a particular training scheme and particular diving arrangements. Trying to somehow 'cheat' the NDL only diving rules by using a different algorithm or settings is a particularly odd bit of self deception.

 

[Rhone Man]

I usually set my Suunto D9 to account for a mix of 23% when I am breathing air. It is still less conservative on every dive than my Sherwood is for air (on my other wrist). It is not exact, but if anyone thinks that any deco algorithm is, then they clearly need to read more in this field. For me, keeping it set at 23% makes perfect sense, but don't blame me if you do that and get bent.

I tend to agree that general conservativeness is the second or third most pressing problem with Suuntos (the Helo2 excepted). Their algorithm also off-gases much more slowly than other models. Accordingly, if you are doing a week on a liveaboard and are doing 4 to 5 dives a day, plan to spend a lot of time hanging on your last dive(s) of the day in the second half of the week.

But the other thing that really just slays me about Suuntos is the draconian penalties they apply if you go above your deco ceiling. (Yes, I am aware that you are not meant to do that.) Just for background - unless you are really pretty much right at your deco ceiling, Suuntos penalise your off gassing rate heavily, so you try to leave the minimum margin possible. Otherwise you might actually never actually be allowed to surface (that was a joke for those who are not familiar with my style of posting). But if you get bored or distracted, and you break the ceiling and you don't get back under inside of about 30 seconds, it locks you out for 48 frigging hours. This is usually the appropriate time to try an impact test for your Suunto against the floor of the liveaboard.

YMMV.

 

[Scared Silly]

My Suunto Cobra2 has an "attenuated RGBM mode.....the settings/options are "full RGBM effects (100%)" and "attenuated RGBM (50%). As far as I can tell, my older Suunto Gekko doesn't have that option. I don't personally use the "attenuated RGBM" mode, but if I understand the manual correctly it is less conservative than the "full RGBM" mode.

This … the "newer" versions have the 100% or 50% option. When I was diving a Suunto I just selected 50% and it came very close to matching my cut tables for deco. Good enough. Otherwise, I left it at 100% and never found it too conservative for my style of diving. If you like the Suunto otherwise just put it in the 50% mode.

 

[miketsp]

My wife and I have been diving Suunto Vypers for may years now and generally we're very satisfied with the profiles. Before moving to the Suuntos we used a more aggressive brand and my wife was getting occasional skin bends. After the change this never again happened.

The only negative point for me is the absurdly accelerated O2 loading if you exceed 1.4PPO2.

The NOAA exposure limit is 45mins at 1.6.
Due to a change of site we needed to go to 1.5 with the gas we had. Knowing that this was going to be a very effortless dive and our good SACs we planned our bottom time to be 30mins based on our rock-bottom and I accepted the 1.6 limit.
So we started the dive and although I had expected the constant PO2 alarm at around 1.5 I was surprised by the rapid climb of the OLF bar graph.
Both Vypers toxed us out at a 100% OLF after only 22mins. No deco time was still 13 mins and we still had a lot of gas in the tanks.

I made a post about this
http://www.scubaboard.com/forums/co...-non-deco-limits-post7117147.html#post7117147

 

[Agility]

If you are really interested in the RGBM and what influences the NDL you could try to geta copy of
REDUCED GRADIENT BUBBLE MODEL by R.Wienke
published in Znt JBiomed Comput. 26 (1990) 231-256

I am afraid my character set will not display the Greek letters properly so pasting the relevant paragraph is not possible, but it amounts to a variable that is increased or decreased by conditions as are:
It will increase monotonically with surface interval
decrease with dive duration, with depth of the dive and with reverse profiles.

IIRC a second variable penalizes fast ascents.