discrepancy between computers

[Doug Krause]

I would like for someone from Oceanic to give me an answer. Do they monitor this?

Today, I had my 15-yr old son completely blow off a mandatory 25 minute deco stop (well we did stop for about 5 minutes anyway) on his computer for his second dive.

His computer seems to work perfectly, today upon our initial descent we compared computers. We had the same (or similar) mix... his computer read 80 feet mine read 77 feet... I had like 54 minutes of NDL he had 24 minutes.. Both computers seem to be working fine.. I am asking Oceanic if this is dangerous or expected?

the damn go-Pro video camera on my head was not pointing down far enough to show the values, but it did pick up some interesting audio.

Sorry I didn't catch your original post. If a deco stop is "blown off" the computer would enter violation mode, not simply provide less no deco time as you've indicated. I've read the post a couple of times... it seems that the deco dive and the subsequent dive you're inquiring about occurred during the same dive day (within 24 hours)? If I'm misunderstanding that and the dive in question followed the violation lockout period, then there's something else going on. Please clarify and we'll point you in the right direction to see if we can help.

 

[redacted]

I would like for someone from Oceanic to give me an answer. Do they monitor this?

Today, I had my 15-yr old son completely blow off a mandatory 25 minute deco stop (well we did stop for about 5 minutes anyway) on his computer for his second dive.

His computer seems to work perfectly, today upon our initial descent we compared computers. We had the same (or similar) mix... his computer read 80 feet mine read 77 feet... I had like 54 minutes of NDL he had 24 minutes.. Both computers seem to be working fine.. I am asking Oceanic if this is dangerous or expected?

the damn go-Pro video camera on my head was not pointing down far enough to show the values, but it did pick up some interesting audio.

That is the kind of result you would expect if one computer were diving 21% while the other was at 36%.

Very similar to the problem I had with a VEO and a Data plus set for 32% but the VEO was giving me NDLs that looked like it was set for 21%.

I don't get to dive EAN that often but I think I will try to recreate the problem on my next trip to Bonaire.

 

[dumpsterDiver]

Sorry I didn't catch your original post. If a deco stop is "blown off" the computer would enter violation mode, not simply provide less no deco time as you've indicated. I've read the post a couple of times... it seems that the deco dive and the subsequent dive you're inquiring about occurred during the same dive day (within 24 hours)? If I'm misunderstanding that and the dive in question followed the violation lockout period, then there's something else going on. Please clarify and we'll point you in the right direction to see if we can help.

My original post explained the situation. my son's oceanic computer boots up records dive time and depth all correctly. We enter in the same notrox mix on two computers.. we descend to 80 ot 90 feet in 100 seconds and he has half the no-deco time I have on the other Oceanic computer.

It was so ridiculous he ended up with 15 or 20 minutes deco on the second dive while I had remainng no-deco time.. It is crazy, every other time I have had a computer fail, it reads error or something or fails to boot up, but this one doesn't do anything like that?

 

[dumpsterDiver]

no help from Oceanic at all????

 

[dumpsterDiver]

Should I keep checking this thread for any help from Oceanic?

 

[BRT]

Are you sure that you are getting the nitrox level set for the second dive? Some of the Oceanics must be set each dive or they assume 21% for deco and 50% for o2 tox. Some can be set up to remember your last setting until the computer shuts off, but you must tell them to do it that way.

 

[Twoblues]

Dsat and pelagic z

 

[Incident]

I agree with BRT here. My Oceanic Geo2 and my Aeris Epic (which are more or less based on the same computer) both require that you set the EAN again for a repetitive dive.

It would be worth looking at the logs to determine if the computers were basing their calculations on 21% for the second dive.

 

[dumpsterDiver]

yes of course i know to set the oxygen level between dives...

 

[scubadada]

Hi Dumpster,

I'm confident you were running both computers on the same algorithm and with the same mix. My guess is that the more conservative computer has a malfunctioning altitude sensor and is computing the dive as being done at altitude rather than at sea level. This is actually how the conservative setting works also. The altitude sensor malfunction can be periodic so that the computer works normally at times but is overly conservative at other times. You can check for this problem by running dive planning on the two computers. The normal one will be on spec regarding NDLs as published in the owner's manual while the malfunctioning one will give short NDLs, perhaps matching the values in the manual if listed for running the conservative setting.

I had this problem several years ago with one of a pair of Pro Plus 2s. Oceanic gracefully replaced the malfunctioning computer with a reconditioned one even though the computer was well out of warranty. I would call Oceanic service and talk it over with them.

Good diving, Craig