diving with two algorithms

[Remy B.]

Just did some diving in Pramuka, since I came for a short weekend stop.

I dive with two DC, a Mares Punk Pro and a Suunto D4i ( christmas give ) did 4 dives, two each day, on my first day and my second dive the Punk Pro was very concervative as it kept me very tight on the NDL, even as I started ascending slowly and stay at a shallower depth to stay in my NDL but eventually I enter in Deco, while the Suunto, for my second dive it lock me in to do it with Nitrox, did not even show me the Air option so I had to change the EAN % to 21 in Nitrox mode, the Suunto never enter in Deco, aldo at max depth they were tracking the same on NDL, but as I ascended the Suunto begin to add more time to the NDL more and faster than the Punk Pro.

At the end I followed my Punk Pro Deco time and surfaced, second day the Suunto still don't even show me the Air option, lock on Nitrox, and there was about 13minutes difference on NDL in some point between both DC's

Honestly my Punk Pro is my choise and is my first DC, the other is may daily watch and was a present from Christmas, I start diving with both just in case one go south on me I still have another one to count on.

Did you think I could had the small or remote possiblity to got the niggles with the Suunto ???, taken that it is a very popular DC, and probably the most sold DC in the marked, is there a trend of who gets more bends or niggles diving with a particular brand DC taken different Algorithms ???

---------- Post added February 7th, 2015 at 10:39 PM ----------

To add a note, the DM was using a Mares Smart, but I never bother to ask him if he enter in Deco as well, I just follow my equipment.

 

[Jim Lapenta]

Why would you just follow your equipment? That is a good way to get hurt. Your computer's don't know you. They don't know your physiology, health, build, etc. Using different algorithms is not something I would ever do or advise a student to do. Put one in gauge mode and use it as a back up bottom timer. Do you really understand how to use these computers? And why are you even coming close to deco? Who taught you that kind of dive planning was acceptable?

 

[Steve_C]

All algorithms are approximations with safety margins. The closer you are to the edge the better your chance of a hit of some kind. I dive two computers, an Aeris and a Zoop. The Zoop is more conservative. (I dove the Aeris for several years before getting the zoop.). I like the fact that the Aeris is a little less conservative but still pretty safe. On a dive I will normally follow the Zoop with the Aeris to use if the Zoop dies. However, the Aeris by being a bit more liberal gives me very useful information if for some reason I am near the end of NDL on the Zoop but would prefer to stay down for a couple more minutes. Perhaps new buddy issue. Perhaps equipment issue. If the Aeris is showing 10 more minutes that tells me something helpful on that dive. MIght just be a buddy who is having some clearing problems on the way up. So we take longer. In any event I always clear both computers on the way up. I know how both computers work in deco mode.

I clear both for safety reasons but the zoop would be really ticked at me if I did not clear it.

Note that most of my diving is offshore ocean diving. I have had a number of instabuddies of differing abilities. I very rarely put the Zoop into "deco" but stuff happens and in our diving you want to go back up the anchor line if at all safely possible. An open water ascent will put you a ways from the boat and drifting away, perhaps rapidly.

I view two computers as extra data to make informed decisions on. I do not necessarily recommend it to a beginning diver. Neither computer is "truth". My increased conservatism as I get older is one reason the first one I listen to is the Zoop. I never ride my air supply. On a good dive I may ride the NDL in the Zoop.

 

[Remy B.]

Hi Jim, I guess you will need to read again some paragraphs.

I only know my own physiology, health, build, etc, but I believe I'm as well in better shape than A LOT of scuba members, I rely on my DC, since I don't do square dives, I assume ( and maybe wrongly ) that is why you mention the bottom timer correct ?, so diving a table in a multi level dive will not help me as I can't re calculate.

No it is not acceptable, since I was following a DM, I may go down or up to see something of interest or pickup garbage.

Yes I know how to use the DC, but don't like one do over the other, since I was diving with air on all four dives I will follow the more conservationist DC.

Yes I know why I hitting Deco, was expecting that the other to be close as well, but since they are running different algorithms it happen that they behaved different and not as close as I was wrongly thinking.

Will I buy another Punk Pro or D4i as my backup DC just to have two that track teh same NO, I just have what I purchase and what was given to me and try to do as best as I can with them, and by asking here maybe not get bend by one of them, anywa I spend a lot of time at 5m at my end of the dive, I guess that is a safer algorithm right ? or should I expect somebody to tell me that spending extra time at 5m is not safe ?

And please nobody ask me who is the DM or for which Agency he was certified If you think he was not doing a good job of daycare with me.

I have done two deco's according my DC, I follow what it tells me, and I add more time at between 5 and 6m, for my own sake in case both DC are out of wak or since I don't know which alborithm is better calculating my multi level dives.

 

[Steve_C]

I have done two deco's according my DC, I follow what it tells me, and I add more time at between 5 and 6m, for my own sake in case both DC are out of wak or since I don't know which alborithm is better calculating my multi level dives.

Are you saying

A. A computer said you were in deco so you added some time of your own choosing at 5 m?

B. A computer said you were in deco and you followed what the computer in deco told you to do in terms of required safety stops and then added some more time at 5 m of your own choosing.

B means that you are following both algorithms and should be safe with high probability. A. is dangerous in my opinion.

I know what you mean by the DM. A few years ago I Had a DM with an aggressive computer put my zoop into deco on the Speigel Grove. I broke off and headed to the down line as soon as I could. I was at 100 ft and there was a ripping current in the top layer. In fact it was my first day diving the zoop, the aeris was in the shop. Fortunately I had read the manual the night before and spent 15 minutes playing flag in the current at 15 ft but all ended well.

 

[Remy B.]

Hi, Steve, I guess you need to read some paraghraps as well, I did say I follow my computer and I ADD more time at 5m.

your comment of the DM, is what I mean, I can't rely on somebody else DC, I follow my equipment since I set the settings on them, doesn't mean one setting is better than the other just I don't know what the others settings are, I have encounter a lot of diver that silent their alarms, taken I assume they are way better diver that I am, and don't need them, I prefer them ON.

 

[Steve_C]

Hi, Steve, I guess you need to read some paraghraps as well,

Did read it. However, however decades of talking to folks with various degrees of mastery of formal English has given me thousands of examples where folks had written things that were not quite what they meant. Just double checking what you meant.

I have encounter a lot of diver that silent their alarms, taken I assume they are way better diver that I am, and don't need them.

Frequently not true as a reading of accident reports shows. Mine stay on also. The threshold levels are set so that if they go on I should pay attention.

 

[clownfishsydney]

Not really hard to work out, just follow what computer is the more conservative. This is what we do on multi-day dives when we run old computers as backups.

 

[waterpirate]

Diving 2 algorithms just makes a diver conflicted. Pick one to use and put your other puter in gauge mode like Jim suggested. Most divers follow this simple gear configuration and cut tables for a backup, wet notes.

As to the niggles? Everyone is different and the best approach is to plan to never get them. If you do get them, you pushed your body to hard on that day.
YMMV
Eric

 

[Steve_C]

Pick one to use and put your other puter in gauge mode like Jim suggested.

But then if the computer dies you are probably done for the day without a computer backup