NERD crapped out, thinking of backup options

[JMBL]

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

To the best of my knowledge, it's cold enough to make most batteries go sleep.

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.)

I mean it's an independent computer, which cannot be connected in anyway to my CCR, and which I used previously while diving OC.

 

[Rollin Bonz]

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.

So....
My recent issues with my NERD forced a factory replacement. Which, after MUCH delay, Shearwater replaced the unit. I was in the middle of a dry spell (Holidays and crap weather), so just put the new NERD with my rig and waited for a chance to get wet. Had the opportunity to dive for the first time since getting the new NERD last weekend. Had a 63 day SI which is unheard of for me. Longest dry spell in probably 6 years. So, I get the unit out to build up and "WTF!", Shearwater had sent me a generic NERD monitor instead of the Optima NERD Controller. I built it up anyway and did the cell checks and it looked as though it was monitoring properly, so I said screw it, I've got 2 methods to monitor PO2 (NERD monitor and a tucked HUD for a backup), I'll fly it manually (we did this almost exclusively during our training and typically run it manually 50% of my dives anyway) and I'm going diving...

Did 2 dives the next day. Didn't die. Seemed to monitor fine, matching the HUD when I checked.

One thing I DIDN'T expect... the solenoid started firing when I got the unit in the water.

Thought the dive was over before it started.... But, I kept watching and breathing the loop. PO2 hit 0.75 and no more firing. Anti-Darwin feature? IDK, maybe. Did the dives, no issues.

@stretchthepenn is my dive partner, so this is partly what prompted the "backup" options discussion this weekend after his NERD failure. "You know, if I hadn't sent that NERD monitor back to Shearwater yesterday, we might have been able to make this work..."

As far why we were discussing a backup option instead of diving OC... We dive the same local quarries REG-U-LAR-LY. Like we know them better than the owners. This is our typical, almost every weekend diving. We dive them for the training and our current training goals revolve around the Choptima. We could have done these dives OC, but what was the point? We could have knocked the rust off our OC Tec skills, but it was the same hole in the ground we've dove hundreds of times, it was cold, with crap viz, and nothing new to see even with good viz. We'd packed our gear and driven 2 & 1/2 hours to dive the Choptimas, and now we couldn't, and we were bummed.

If we'd been in the gulf on the Oriskany and there was an issue, we'd have dove whatever working gear we had, but may have still been bummed. Thus the "backup" discussion.

 

[attack33]

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?

sounds like you could get the NERD fixed under warranty and buy a used Petrel 2 controller at a discount from an individual looking to sell one off their used choptima so they can upgrade to petrel 3.

…I am that individual

 

[Rollin Bonz]

sounds like you could get the NERD fixed under warranty and buy a used Petrel 2 controller at a discount from an individual looking to sell one off their used choptima so they can upgrade to petrel 3.

…I am that individual

 

[tbone1004]

@Rollin Bonz great to know that it will still act in parachute mode if a monitor is connected! The communication protocols are the same and calibration data is stored in the SOLO/OBOE boards not the handsets/NERD's so it makes sense that the calibration points can be done by the monitor and also that the ambient pressure is sent back to the boards to allow parachute mode to run. Not knowing how the firmware is written I don't know what the protocols are in terms of whether the SOLO thought it was a malfunctioning handset and reverted back to it's default which is to maintain the 0.7ish ppO2 if the handset is disconnected or it knew it was a monitor and just defaults to the SP-Low if a monitor is accidentally connected. Super useful intel!!

 

[attack33]

View attachment 765915

$900 + shipping.

It only has around 11 hours on it. Someone did there initial training then sold it to me. I bought the unit used and it was sent to Dive Rite for service and is awaiting me to pick it up for the crossover training.

So I’d have to ensure Dive Rite is cool with shipping it out.

 

[Tracy]

The unit will maintain the last entered setpoint when the controller was removed. This is a safety measure in case your controller failed or came unplugged during the dive. Take that information for what it is worth. You said your buddy's controller worked on your head?
The HUD or monitor nerd will function on either port, though I'm not sure why you would.
I have several controllers, so I tend to take one with me if I am going diving.
Another point, a revo controller will plug in, but the software doesn't jive.
A p2 controller will plug in and run an Optima. And vice versa. Hence why you have maybe seen a p2 with a nerd controller in the wild even though that doesn't actually exist.

 

[LFMarm]

Will do some more testing on this over the weekend