NERD 2nd thoughts...

[rjack321]

rjack321. I got this information directly from Shearwater. The cap is shorter than the fischer cable end and thus does not seal the same way contacting the o-ring in the bottom of the port it relays on the o-ring on the cap to seal. Yes you could use the cap with the mineral oil it is just not recommended and I would suspect that it would not be covered under warranty if there was a problem as its not designed to be dove this way.

And Yes you are correct about getting a computer that does not have a cable or port if that is going to be your primary computer and or you are not looking at diving CCR. My current perdix AI is my primary computer for all OC diving. I have an old 2 gas computer that works as a backup for now but it is limiting. I am working on getting into a CCR and would rather not have to buy a second perdix for 10% or less of my tech diving once I have the CCR. So rather than buying a complete second computer just for when I want to do an OC tech dive rather than a CCR dive if the computer can work for both that saves over $1500cad

Tbone1004, Thanks for the information.

The cap seals with a single Oring just like the cable.

So I have no idea what you are trying to do. The perdix doesn't have a ppO2 monitoring option at all anyway. Plus you don't need a computer with live deco cell monitoring at all you know? Lots of CCRs only have a ppO2 display and you run the deco on a stand alone fixed ppo2 computer like your perdix. Deco calculations are not as sensitive to small variations in ppO2 as you'd think. You can use the perdix to run your deco or as a backup computer and still even do OC dives with it in the future.

Although if you don't even own a CCR yet you are years away from doing deco with one.

 

[allpointswest]

The cap seals with a single Oring just like the cable.

So I have no idea what you are trying to do. The perdix doesn't have a ppO2 monitoring option at all anyway. Plus you don't need a computer with live deco cell monitoring at all you know? Lots of CCRs only have a ppO2 display and you run the deco on a stand alone fixed ppo2 computer like your perdix. Deco calculations are not as sensitive to small variations in ppO2 as you'd think. You can use the perdix to run your deco or as a backup computer and still even do OC dives with it in the future.

Although if you don't even own a CCR yet you are years away from doing deco with one.

What is wanted is to have the ability to use a petral 2 as a "back up" computer (my current perdix is my primary) on OC dives as well as use the same computer as the "backup" PO2 monitoring computer on the CCR. Because yes you are correct the Perdix does not have PPO2 monitoring and it doesn't need to. And you are correct that you can run the perdix in CCR mode and set the PPO2 as a fixed point on it. And yes you are correct that the differences between deco times will not be that far off between a perdix running in CCR mode with the correct set point vs a hardwired petral 2 or nerd 2 that sees the true PO2. The issue with that setup is only having one point of O2 cell read out. Any Technical CCR diving should have two points of reading the O2 cells which would for my self on a Kiss Sidewinder will be a petral 2 and a nerd 2. The question comes down to the connector between the CCR and the computer. It sounds like the 4pin wet connector is the way to go for this purpose.

And I don't agree with your comment about years away from doing deco on a CCR. With the correct training and time on the unit along with personal skills this doesn't have to be the case. And I know that when I am talking to instructors we are looking at doing the training with Deco included. If someone is more comfortable waiting years to get experience on a unit then that is great and there personal choice.

 

[rjack321]

Awesome, I totally needed to be mansplained today. See you over in the A&I forum shortly!

 

[allpointswest]

Awesome, I totally needed to be mansplained today. See you over in the A&I forum shortly!

Sorry wasn't my intent I thought you were actually wondering where I was coming from and that I hadn't been clear.

As for the A&I. Thank you for the concern it is honestly appreciated. And yes taking it slow isn't a bad thing and I will be doing that and building up hours. That said you don't know my experience, skill or training level. Where or how often I dive, or the level of risk I personally am willing to take. I am in the infancy of my diving career at 13 years in with a ton to learn. I do dive cold water diving and year round. pushing between 150-200 dives a year.

 

[doctormike]

And I don't agree with your comment about years away from doing deco on a CCR. With the correct training and time on the unit along with personal skills this doesn't have to be the case. And I know that when I am talking to instructors we are looking at doing the training with Deco included. If someone is more comfortable waiting years to get experience on a unit then that is great and there personal choice.

That said you don't know my experience, skill or training level. Where or how often I dive, or the level of risk I personally am willing to take.

Many of the posts in these advanced forum aren't really aimed at the person being replied to. I think that it's important to call out dangerous behavior so that other new or potential CCR divers don't read it and assume that it's normal. That's normalization of deviance.

Your experience, skill or training level aren't really relevant - you shouldn't do deco on a CCR until you have logged a good number of hours on a rebreather. I'm no instructor, but I wouldn't train with someone who wanted me to do my first MOD1 class and deco training at the same time.

 

[stuartv]

I am now planning to contact them to see if the computers (petral 2 and nerd 2) can be ordered with the 4 pin wet connector ready to work with the reading directly off the 3 cells. and skip the fischer cable all together.

It might be worth contacting Shearwater to see if you can ship your computer back to them to have the 4 pin cable installed which sounds like it can get wet with out issue. (proper cleaning required). If shearwater can't Mike Young answered a question I asked on FB and they sell the nerd 2 with the 4 pin wet connector directly from them so they might also be able to retro fit your existing computer. They will also have the molex to 4 pin cable for the head of the ccr.

The rEvo NERD2 Monitor (as opposed to a rEvo NERD2 Controller) is exactly what you are talking about. It has the 4-pin DiveCAN-style cable that connects to a cable installed in the rEvo that goes straight to 3 molex connectors that connect directly to the O2 sensors. For that reason, I don't think you can order a NERD2 setup like that, nor get one converted to that. I think the Shearwater line is that you have to buy a rEvo one, if that's what you want.

rEvo also, of course, has the cable that goes from the 4-pin connector to 2 or 3 (your choice) molex connectors. Note that those molex connectors are correct for the type of O2 sensor that rEvo uses. I think some other CCRs use a different style of molex connector.

Who is Mike Young? I would love to know about it if there is a source to buy a NERD2 with the 4-pin cable that is not priced the same as the rEvo version. The NERD2 with Fischer connector is several hundred dollars cheaper and that is part of the reason that I bought my NERD2 with Fischer connector. That and the fact that my rEvo already had the Fischer cable connected to the O2 sensors, which was previously used by connecting to a Predator EXT.

It sounds like maybe Mike Young is a rEvo dealer and selling parts that are made for a rEvo?

Although if you don't even own a CCR yet you are years away from doing deco with one.

I think both IANTD and TDI allow for a diver with OC AN/DP (or equivalent) to do their initial CCR training to include deco. My very first CCR training included deco and use of helium (as I already had TDI Trimix certification). I only have 70 hours on my unit, so far, but it hasn't been a problem yet. Of course, I didn't come right out of my training and immediately start doing big deco dives. Actually, I feel like I have not done any CCR dives yet at all that qualify as "big" deco dives. My certification only allows for a max of 15 minutes of deco anyway. Regardless, it seems like an assertion that someone whose training goes that way will be found in A&I is a bit hyperbolic.

 

[tbone1004]

@stuartv those subconn connectors are only available directly through Revo and KISS. Dealers and distributors are not able to purchase them.

Mike Young owns KISS.

 

[stuartv]

Your experience, skill or training level aren't really relevant - you shouldn't do deco on a CCR until you have logged a good number of hours on a rebreather. I'm no instructor, but I wouldn't train with someone who wanted me to do my first MOD1 class and deco training at the same time.

Experience, skill, and training are all relevant to any instructor who is taking care to meet standards.

And standards allow for OC deco divers to include deco in their MOD1 training.

My instructor did not push me to do deco and incorporate helium into my training. I requested both. I wanted to be able to dive deeper than 100' and to be able to do some deco. And, for safety in diving a CCR deeper than 100', I wanted to be able to use helium. My instructor agreed to all that. I vetted my instructor as best I could and then vested my trust in her not to certify me and send me off to do something that was going to get me hurt. And, I am pretty confident that my instructor would not have certified me if I had not demonstrated adequate buoyancy control (and the other necessary skills) by the end of my training.

If my instructor deems that I have adequate buoyancy and the other necessary skills (including the proper mindset) to do CCR deco dives, what's the problem? The only real problem, I think, would be if you trained with a crap instructor. In which case, you're in trouble, deco or not.

 

[stuartv]

@stuartv those subconn connectors are only available directly through Revo and KISS. Dealers and distributors are not able to purchase them.

Mike Young owns KISS.

Thanks! Does that mean KISS sells a NERD2 monitor that would work directly with a rEvo that has the rEvo 4-pin cable installed?

And, could KISS modify a NERD2 with Fischer connection to have a 4-pin connection? Or have Shearwater do it for them?

 

[tbone1004]

Thanks! Does that mean KISS sells a NERD2 monitor that would work directly with a rEvo that has the rEvo 4-pin cable installed?

And, could KISS modify a NERD2 with Fischer connection to have a 4-pin connection? Or have Shearwater do it for them?

Theoretically they are compatible.
Theoretically they could be converted, however Shearwater won't do it, and I can near guarantee that KISS and Revo won't touch it because it would void any warranties through Shearwater. The Fischer cables can be crimped onto the end, but the Subconns have to be made at the factory, similar to EO cords