Nerd and petrel vs 2 petrel

[Heat Miser]

Not sure how to read your post. NERD and HUD are on the loop. When the loop is off, yeah, you can't see the computer. But you've already bailed, it is not like you need to monitor your PPO2. You still have Petrel and potentially, other computers.

What am I missing? And yes, I've bailed out w NERD.

because the HUD on a rEvo is linked to a dream, so you can bail-out and still read your PPo2 on the dreams without looking at the HUD. Say you have a solenoid stuck open, you bail-out and then dil it down before going back on the loop and feathering the o2.

 

[mr_v]

because the HUD on a rEvo is linked to a dream, so you can bail-out and still read your PPo2 on the dreams without looking at the HUD. Say you have a solenoid stuck open, you bail-out and then dil it down before going back on the loop and feathering the o2.

Ok, what you said makes sense and is very specific to your configuration. Not everyone has Dreams.

Note, the OP wants to compare two configurations: Petrel + NERD or 2 Petrels. Given that info, I suggest Petrel and NERD.

 

[Heat Miser]

But you've already bailed, it is not like you need to monitor your PPO2.

Ok, what you said makes sense and is very specific to your configuration. Not everyone has Dreams.

Note, the OP wants to compare two configurations: Petrel + NERD or 2 Petrels. Given that info, I suggest Petrel and NERD.

As long as your clear, you need to know your PPO2 after you've bailed out.

A couple of months ago some friends from the dive club had a couple of Hyercapnic events on the same dive (not on revos). One of the guys, a dive shop owner, had the soundness of mind to go back on the loop and run the machine as a sort of SCR, in order to get through their deco obligations and conserve gas.

 

[mr_v]

As long as your clear, you need to know your PPO2 after you've bailed out.

A couple of months ago some friends from the dive club had a couple of Hyercapnic events on the same dive (not on revos). One of the guys, a dive shop owner, had the soundness of mind to go back on the loop and run the machine as a sort of SCR, in order to get through their deco obligations and conserve gas.

Yeah, of course. There are many details there, but I don't want to hijack the thread. One point, you'll still do a dil flush as you return to the loop, so by that time you'll see NERD/HUD.

My point is that between two Petrels and Petrel + NERD, I'd go with Petrel + NERD, as NERD is convenient in 99% cases. The cost difference is about $1K and is worth it.

 

[Wibble]

Not sure how to read your post. NERD and HUD are on the loop. When the loop is off, yeah, you can't see the computer. But you've already bailed, it is not like you need to monitor your PPO2. You still have Petrel and potentially, other computers.

What am I missing? And yes, I've bailed out w NERD.

there’s a Petrel on the wrist and the Nerd on the loop. When bailed out you need to let the computerS know that you’ve bailed in order to calculate the deco with the new variable gas. You’ll probably only use one of the computers for Shearwater Cloud, most likely the Nerd if using AI.

When off the loop it’s inconvenient as you need to unclip it and use two hands to click buttons.

 

[AJ]

As long as your clear, you need to know your PPO2 after you've bailed out.

Why? Knowing PPO2 is important when you're on the loop. Why would you want to monitor PPO2 in the loop when breathing bail out gas? Selecting the right bail out gas (right PPO2) is very important of course.

My point is that between two Petrels and Petrel + NERD, I'd go with Petrel + NERD, as NERD is convenient in 99% cases. The cost difference is about $1K and is worth it.

Completely agree. Don't plan to bailout often. For these cases where I have to bail out, the inconvenience of not being able to read the NERD directly is acceptable to me. Use a slate and Petrel for bail out plan. Only if the Petrel craps out, I will have to use the NERD.

 

[Heat Miser]

Why? Knowing PPO2 is important when you're on the loop. Why would you want to monitor PPO2 in the loop when breathing bail out gas? Selecting the right bail out gas (right PPO2) is very important of course.


Completely agree. Don't plan to bailout often. For these cases where I have to bail out, the inconvenience of not being able to read the NERD directly is acceptable to me. Use a slate and Petrel for bail out plan. Only if the Petrel craps out, I will have to use the NERD.

Because of the two examples above requoted below plus a few more, using a BOB for example

Say you have a solenoid stuck open, you bail-out and then dil it down before going back on the loop and feathering the o2.

A couple of months ago some friends from the dive club had a couple of Hyercapnic events on the same dive (not on revos). One of the guys, a dive shop owner, had the soundness of mind to go back on the loop and run the machine as a sort of SCR, in order to get through their deco obligations and conserve gas.

Why did I log back in to Scubaboard? I have been so good the last 2 weeks, 22 real dives in the Maldives, no Alchohol, desert every night .... now back to the real world

 

[lostsheep]

. It works for some people’s use, particularly those not scootering a very long distance

I have a HUD but several of my buddies have the nerd and longer scooter runs are basically all we ever do.

I’m curious what your objections are for scootering?

 

[beldridg]

@beldridg is a big supporter of the Nerd on a rEvo and has written and posted on his blog a bit about It.

Me I'm a cheapskate and just went the dreams and HUD.

My main thinking was redundancy and simplicity on expedition trips such as Bikini (planned for next year). So I would manually dive my unit if I had a controller failure using the dreams to read 4 cells. However I have had my share of troubles getting used to the bulky dreams, especially whilst diving with gloves. I have clipped stages off to them, unclipped stages, dropped stages, it was an expensive learning process.

The dreams now clip off to a set of UK Sump drop-down D rings on my waist for my BO bottom gas and deco gas stages.

Yes, I dive with a Petrel controller and a NERD "monitor" (and an off board Teric).

As @Wibble mentioned, the compass is very useful. I did a couple dives today and on both I found my primary target but then did a search pattern to look for other debris. It is VERY useful IMO to have the compass in line with your line of sight and always available.

I don't check my AI pressures very often in the NERD but I have written in the past about how on one dive they helped me quickly identify a problem.

I also like the NERD on descent to give me an idea of where I am relative to the bottom in the cold, dark, sometimes very low visibility waters here in SoCal.

When I don't want to see it, I just rotate it down.

I do agree that it is not that great on bailout, but when I've had to bailout (only once in real life but plenty of times in classes), I personally keep the loop under my chin and change my Petrel first, then my NERD then my Teric.

I do also like the NERD on deco because it just makes it so easy to monitor your stops and time remaining.

All of that being said, I understand why some people don't like it. It is somewhat "in your face" but that is what it is designed for. The great thing is that we all have options.

- brett

 

[beldridg]

PS - I also like the idea of a second on-board computer that not only monitors my PO2 but also calculates my deco.

- brett