Déjà vu?

Déjà vu?

What is a NERD? What is AI?

I recently upgraded my Dive Rite O2ptima rebreather with the new back mounted counter lungs and the built-in bail out valve (BOV) mouthpiece, (which allows me to breathe from the rebreather or open circuit without having to remove it from my mouth)

Upon much encouragement from diving buddies Dr. Mel Clark, Becky Kagan Schott and Brian Kakuk, I finally purchased a new Shearwater NERD 2 to go along with my newly updated O2ptima in March of 2018.

My new NERD 2 came with a digital compass and AI capabilities… (fun stuff!).

What is this AI? I always thought that AI stood for artificial intelligence. Unfortunately, no, the NERD 2 is not artificially intelligent... yet. However, in this particular case AI stands for Air Integrated. It is just a clever way to get wireless pressure gauge readings from 2 separate scuba cylinders at the same time.

In late April 2018 I went to the TEKDiveUSA show in Orlando, Florida and acquired a new Perdix AI, along with two transmitters. This one also came with a digital compass! It looks similar to the handset on my O2ptima but this computer lacks a cable to connect directly to my rebreather. It is a standalone personal dive computer that is replacing my much older wrist computer. I can set it to dive in CC/BO mode applying a fixed ppO2 value and use it as a back up to all my rebreathers. I can also use it for all my open circuit diving.

At that point in time I had to face a special kind of hardship: I had new toys and no time to read up and install the transmitters. My teaching schedule kept me for over 2 weeks…

Eventually decision time came up. Which gear configuration will get the transmitters: the open circuit sidemount, the KISS Sidekick, the Sidewinder or the O2ptima ?

The O2ptima with the NERD 2 already had the AI functionality. But both first stage regulators only have one usable high pressure port each… and guess what? Yes, both ports already had high pressure hoses with conventional pressure gauges, one for the oxygen tank and the other for the diluent tank.

The only way to use the transmitters is to remove and replace the submersible pressure gauges completely. This was something that I never thought I would do. How much faith do I have in these transmitters? I did play with a wireless transmitter from another brand over 25 years ago. It was just for open water diving. One day I lost my wrist display on a drift dive off West Palm Beach. That ended my wireless involvement. None of us back then considered using those transmitters in cave diving.

Cis-Lunar Mk5

But then again, back in 1998, I was using the Cis-Lunar Mk5 rebreather and it had digital pressure readings for both the diluent and oxygen cylinders. They were using a pressure transducer and internal wires to the handset (wrist dive computer). It had no conventional high pressure hoses nor pressure gauges. At that time I did not miss having regular SPG’s. Was it a peek into the future?

Well, here I am, 20 years later and about to go wireless! The tipping point came just a few weeks after TEKDiveUSA. While at the NSSCDS International Workshop on May 19th, 2018, I saw Jared Hires’ O2ptima on display with the AI transmitters. That cemented my decision to go wireless with my O2ptima. No more conventional SPG! I was willing to put my faith in these transmitters.

A few days later, my friend Tony Flaris and I set up both the Perdix and the NERD 2 to read both O2ptima tanks. Now I have a redundant PSI display on the Perdix. Perfect for cave diving. The PSI units can be easily converted to the metric numbers should I ever decide to go metric.

As of August 9, 2018 my NERD 2 had 38 logged O2ptima dives since March. The Perdix has 65 dives in the last 2 ½ months, a combination of CCR sidemount, open circuit sidemount, O2ptima and open water dives. The transmitter is very reliable and has worked flawlessly. At least for me, the days of the submersible pressure gauge are numbered now…

I wonder why I waited so long to go high pressure hose free! Now I have to figure out how to outfit my CCR sidemount system, my open circuit sidemount… you know how it goes with technical dive gear. It's a never ending story!




Written by Paul Heinerth

Paul Heinerth began diving the springs of Florida in 1971. He has been a member of the US Deep Cave Diving team since 1987. He started using rebreathers in 1993. He is still very active teaching cave diving, rebreather diving, Trimix and is always ready for another expedition.