Oceanic VT3 End Pressure...Bug?

[Cleavitt]

On my last 4 dives I have noticed that the dive details (oceanlog 2.1.0) tank pressure is not accurate. I noticed while reviewing a dive that the records at the end of the dive showed I had only 90 PSI remaining. However, the "dive" tab shows the end pressure as 550 PSI which matches my memory of the computer display at the end of the dive. Thank god for that because for a minute I thought I had really screwed up. This must be a bug because it doesn't make sense for the dive detail records to be less than the end pressure value (with the exception of small amounts due to rounding).

This issue did not occur on previous dives. I assume the bug is related to the 2 second polling interval because that is the only setting I changed recently and it coincides with the issue. Previously, my VT3 was set to a 15 second polling interval and this issue never occured in those 25 dives. I will be diving again this weekend with the VT3 set back to 15 seconds and I will confirm the issue is resolved (or not) at that time.

Is Oceanic aware of this issue? Is there a fix for it? New firmware perhaps?

Let me know if you need more info or a copy of my log file.

 

[philmayer]

I know this is an issue in some of the versions of Oceanlog released this year. Try upgrading to v2.1.7 and see if the problem goes away. The issue was supposed to be fixed in this or an earlier release.

The VT3 records certain data during each polling interval. It really has no way to cause the issue.

The latest version of Oceanlog can be found here:
Oceanic Worldwide - Owner Services - Software

 

[Cleavitt]

No luck. I downloaded 2.1.7 and installed it. I deleted my last 2 dives from OceanLog and re-imported them from the VT3. The values are the same. In each of these dives the pressure on the details is off by several hundred PSI.

 

[Doug Krause]

Very strange - time to get our support guys on it. Please contact David at 800-435-3483, ext. 431 or ddrisdale@oceanicusa.com - he'll be glad to help.

 

[MissionScuba]

Great catch Cleavitt. I too was baffled with my dive logs showing me out of air when I know I had air remaining in my tanks. I even sent my Oceanlog data to Oceanic for evaluation and they came up with nothing. Oceanic's response was: "After reviewing your data and obtaining assistance from several other disciplines within engineering, I spoke with you regarding your VT3. We have not been able to duplicate the problem you described regarding Gas Switching."

(Yes, I made sure I had the most recent firmware, and the most recent Oceanlog version before I even called)

I am an avid tech diver, and have dived dozens of deep (150+ feet) multi-gas dives with my VT3. They offered to replace my VT3, but I know it was not a faulty unit, because I wear my wife's as a backup, and hers would do the same.

It's a bummer, because I love Pelagic units, and I have had great experiences with Oceanic until this point. My local scuba shop says it's quite uncharacteristic of Oceanic.

There are some other small issues with status messages coming at inopportune times when diving deep with the VT3. These would be such minor changes in future firmware updates, and I'm sure Pelagic just isn't aware of them due to the lack of qualified people that can evaluate their PDCs on dives deeper than 150 or 200 feet. I've learned to set my backup VT3 with slightly different FO2 values so that the "interfearing" messages pop up at different times, so that I always have one I can view for valid & current info.

As an example, where we dive, it's deep and dark, so you can't always see if you're going up or down, so we rely on our computers for our depth. (Those of you that dive with doubles know you can start ascending or descending rapidly and not even know it when you can't see any terrain) The VT3 will sometimes take away your current depth and show you maximum depth for that dive while displaying a message such as "Low Time", which is also invalid considering we're diving with doubles and stage bottles. So all of a sudden getting a message that you're at 215 feet when you think you should be at 90 is scary!

I guess I'm just another ranting idiot.

 

[Doug Krause]

MissionScuba - I'm not sure that I understand your last point regarding a "Low Time" warning - and how that implies that you're at 215 feet? I'd be glad to discuss specific issues that you're having on these profiles with our R&D group - but need some details. Feel free to PM or email me.

Best,

 

[The Chairman]

Thank goodness you guys didn't load it with WINDOWS!

I have quite a number of dives on my VT3 and have as of yet to have this problem. I just love mine. Have you changed the batteries in your transmitter? Also, is this happening as you are breaking down your regs for the second dive?

 

[MissionScuba]

MissionScuba - I'm not sure that I understand your last point regarding a "Low Time" warning - and how that implies that you're at 215 feet? I'd be glad to discuss specific issues that you're having on these profiles with our R&D group - but need some details. Feel free to PM or email me.

Best,

Hi Doug.

Thanks for the response. I'll elaborate on what I was describing, and I'll try to reproduce some of the messages on my dives this Thursday, and write down the messages as they come.

Say, for example, my maximum depth for a dive is 210 feet. Additionally, I may be working hard at 130 feet, so my air consuption is accelerated for 2 minutes or so, so the VT3 air-time-remaining algorithm is basing it's air time on 130 feet and at the SAC rate polled in the past 2 minutes. When the VT3 switches to a LOW AIR TIME (or it may be LOW DIVE TIME, not sure - I only notice LOW and TIME) gauge warning/alarm, instead of my current/actual depth displaying in the bottom right of the screen, it shows my maximum depth for that dive.

I often get this message on dives because the VT3 is only considering my back gas (TMT1) and not my deco/stage bottles, and I can understand that. I believe the maximum depth displaying on the LOW TIME screens is just an oversight.

Another somewhat important message is a high PO2 warning when switching to a deco gas. Say I'm diving with a 50% mix in my stage bottle, and so I will be switching to it at 70 feet, and I have a 30' ceiling for 6 minutes. When I switch to my 50% and change to TMT2, a UP HIGH PO2 warning will show in the upper window instead of displaying my 30' ceiling. I have to go shallower before the UP HIGH PO2 warning will clear. I will still see the 6 minute countdown, but I won't know the 30' stop. I've learned to make a note of it before my gas switches.

I also had something similar happen when I had a transmitter go bad. The link on
TMT2 was lost, and it showed TMT2 LINK LOST in the display instead of my required ceiling depth for the remainder of the dive.

Just a side note... My VT3 is spectacular on normal recreational dives. No complaints at all. It's only when tech diving. It would be great to be able to turn off some warnings all together, but that would be a stretch, and quite a liability I'm sure.

Thank you.

Russ

 

[SpiderSense]

cleavitt. i had the same problem. i thought the computer would continue to calculate the end value after the dive ended. meaning, if i were to change tanks within 10 mins of the dive, the end pressure would be super low. now i make sure i get on the boat, take my computer off and strap it to my first stage (or near), and leave it for 10 mins before closing the tank. at one point, i also used 2 sec polling, but switched back due to other issues. hmm.. i don't remember if my workaround occurred before or after i switched back to 15 sec. give it a try tho.

 

[scardner]

Did anyone ever find a fix for this? Mine did the same thing last night. At 80 feet the VT3 started screaming at me "Low Air Time" and displayed 180 psi of pressure. I was diving doubles with 2400 psi of pressure. Did it twice moreduring the dive so I went off my analog gauge for the remainder of the dive and ignored it. I'm on the 2 second sampling also...