NERD crapped out, thinking of backup options

[stretchthepenn]

Yesterday, my buddy and I went for a dive with our Choptimas but had to abort due to a NERD death. The situation left us wondering about how to best prepare a backup solution, and I'd like y'all's input.

Here's the story... My buddy and I each pre-built our Choptimas the night before, and everything checked out normally. However, when we arrived at the dive site and I powered up my NERD, the unit crapped the bed. The readout gave me a "No Connection" notice and reported "0.0" for all sensors.

We did a bit of troubleshooting: I disassembled my rebreather and examined the head, but the connections were all good. I powered up the HUD, and it read out correctly for atmospheric air. We then swapped NERDs; my NERD reported 0.0/No Connection on my buddy's Choptima head, and his NERD reported 0.21 all the way across on my Choptima head. Thus, we figured that my NERD was the problem. (If it's not, then please tell me why we're both idiots so we can learn from this situation.)

What with my controller going tits-up, my buddy and I figured that the diving day was a bust, so we packed our crap and went home. But we were left wondering how, if such a situation ever occurred again, we could salvage a dive-day. Short of buying another NERD, could we

• get a used Fischer Petrel controller for cheap and get it converted to DiveCan?
• get a Petrel monitor or double up on HUDs and fly the Choptima in full-manual mode?
• do something else we'd not considered?

Whatchoo-all think?

 

[grantctobin]

• get a used Fischer Petrel controller for cheap and get it converted to DiveCan?
• get a Petrel monitor or double up on HUDs and fly the Choptima in full-manual mode?
• do something else we'd not considered?

Whatchoo-all think?

If it is a Fischer, it is not a controller.

I do not think it is sound and would never encourage someone to run a pair of HUDs.

Either have a backup Petrel controller between the two of you or ditch the NERD2. If your next issue isn’t the connection issue, it’ll be the depth sensor issue and your NERD will never surface again. They’re decent when they work, but they’re not nearly as reliable as Petrels and most people don’t like to discuss the frail nature of the depth sensor connection inside the case.

 

[JMBL]

I assume the problem occured while outdoor. What was the temperature then ? In my experience, many electronic appliances do not like at all low temperatures, that may be the cause of the problem.

Concerning the backup solution, I'd get a Petrel (not connected). I'm diving a Triton with a connected Petrel 2 and my Petrel 1 stands as backup. My buddies who dive a Triton + Nerd, also have a Petrel or Teric as a backup.

 

[stretchthepenn]

If it is a Fischer, it is not a controller.

Didn't know that about the Fischer models... Good info, thanks.

I do not think it is sound and would never encourage someone to run a pair of HUDs.

Just for curiosity's sake, what's the reasoning?

Either have a backup Petrel controller between the two of you or ditch the NERD2. If your next issue isn’t the connection issue, it’ll be the depth sensor issue and your NERD will never surface again. They’re decent when they work, but they’re not nearly as reliable as Petrels and most people don’t like to discuss the frail nature of the depth sensor connection inside the case.

I wear glasses/contacts, so for me, the NERD is a better option as a primary controller.

 

[stretchthepenn]

I assume the problem occured while outdoor. What was the temperature then ? In my experience, many electronic appliances do not like at all low temperatures, that may be the cause of the problem.

The air temp was brisk but not actually cold; it was in the low-to-mid 40s F (5-8 C).

Concerning the backup solution, I'd get a Petrel (not connected). I'm diving a Triton with a connected Petrel 2 and my Petrel 1 stands as backup. My buddies who dive a Triton + Nerd, also have a Petrel or Teric as a backup.

By "not connected," do you mean your Petrel 1 is a monitor, or do you mean it's a totally independent dive computer? I'm running two Perdix AI computers as bailout backup, so I dunno if I need another ordinary computer.

(And yes, two Perdix AI backups is overkill, but they're mounted on wrist-slates, so I'm just giving myself extra writing surfaces.)

 

[grantctobin]

Caveat I’m not actually sure the board will allow two HUDs, but assuming you’ve tried it…

Just for curiosity's sake, what's the reasoning?

I think there’s quite a bit of primacy and habit learning when it comes to primary monitoring method. People tend to fall into either the “the only thing that is important to me underwater are the lights on the HUD being what I expect” or the “I use my computer to tell me that information and only use or turn on the HUD when the primary fails” camp. If you’re in the former, two HUDs is likely less of a decrease in safety than going from being a dominant NERD or dominant Petrel person to using simply HUDs. As a HUD-centric person, would I suffer through a pair of HUDs for an easy recreational dive? Sure. But why am I bringing a unit in the first place on that dive? I did play with a HUD and a NERD in conjunction on a pair dives when I was in the process of modifying electronics and found myself focusing solely on the NERD and sliding the HUD under a loop cover.

Then, we get into the “I’m flying the unit in full manual” issue of two HUDs. Do you normally fly the unit fully manually? How many solenoid triggers do you average per dive?

So now we’ve gone from eCCR and potential NERD dominance (and HUD either mounted or tucked or dangling between the lungs as one Choptima instructor encourages on the Choptima FB group) to a non-CMF, non-dominant monitoring system.

Eh. Bring OC bailout or accept that your NERD2 will need an RMA once or twice every couple years.

I wear glasses/contacts, so for me, the NERD is a better option as a primary controller.

the obvious trade off here is their fragility and the weight on the loop on long scooters. If you are doing dives that cannot be missed and your optical situation renders a Petrel impossible, bring a second unit or an additional Nerd controller. That said, if you’re unable to use a Petrel as a controller, how do you view your backup computers on your wrists?

 

[tbone1004]

@stretchthepenn as @grantctobin said, if the NERD is your controller then it is unit specific to the O2ptima. Anything with a Petrel is going to be an analog unit and can't communicate with the DiveCAN as that is a digital canbus network, they are not even remotely compatible with each other. Your true only option for that is to have a backup controller. Cheapest would be a Petrel controller but it has to be an O2ptima specific controller so you will have to order from Dive Rite. If it was a monitor like your HUD is that is on the other side of the bus then those are universal across DiveCAN. Of note, the O2ptima version of the NERD from DiveGearExpress is the monitor and not the controller so it won't work on the SOLO side of the bus, only the OBOE.

Keeping a spare controller isn't necessarily something that I would normally feel the need to recommend either.

@JMBL this failure was on the controller, rebreather is not diveable without a controller since the solenoid will not fire. The only option for a backup in this case is a unit specific controller and in this case that is either a Petrel or NERD.

 

[Rollin Bonz]

@stretchthepenn as @grantctobin said, if the NERD is your controller then it is unit specific to the O2ptima. Anything with a Petrel is going to be an analog unit and can't communicate with the DiveCAN as that is a digital canbus network, they are not even remotely compatible with each other. Your true only option for that is to have a backup controller. Cheapest would be a Petrel controller but it has to be an O2ptima specific controller so you will have to order from Dive Rite. If it was a monitor like your HUD is that is on the other side of the bus then those are universal across DiveCAN. Of note, the O2ptima version of the NERD from DiveGearExpress is the monitor and not the controller so it won't work on the SOLO side of the bus, only the OBOE.

Keeping a spare controller isn't necessarily something that I would normally feel the need to recommend either.

@JMBL this failure was on the controller, rebreather is not diveable without a controller since the solenoid will not fire. The only option for a backup in this case is a unit specific controller and in this case that is either a Petrel or NERD.

So, tbone, what should theoretically happen when you plug a generic NERD 2 monitor into the SOLO side of the Choptima? Ummm, asking for a friend

Edit: I mean other than it not functioning as a controller. Would a monitor theoretically NOT function as a monitor on that side?

 

[tbone1004]

So, tbone, what should theoretically happen when you plug a generic NERD 2 monitor into the SOLO side of the Choptima? Ummm, asking for a friend

Edit: I mean other than it not functioning as a controller. Would a monitor theoretically NOT function as a monitor on that side?

I have not tried with the current firmware revisions so can't comment and don't own a DiveCAN rebreather otherwise I would certainly have tried it by now ;-) . It shouldn't break anything but I imagine something is going to throw some sort of error code. Will probably read out ppO2 though. It's an interesting concept though and one where I certainly prefer the Liberty implementation where both sides of the bus are identical and whichever one is turned on first becomes master and the other operates as slave.

 

[rjack321]

Whatchoo-all think?

It's just a dive. Go swim around on OC or pack it all up and go home. Jury-rigging spare controllers is a bad idea with any unit.

Alternatively, permanently switch to a much more reliable petrel controller.