Mares Horizon - few questions before the decision about course.

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Wibble

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The first second hand one I've seen just came up for sale on FB in OZ.

I had been suggesting to my wife that we could get it for her IE similar deco profile to my rEvo 0-40m. The exact reply is I don't want to mess around with anything I have to build, if I dived that you would be building it for me, I.E. she talked me out of it, pretty quickly.

Wise wife
 

Bernie_U

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It "might" be easier to dive than a full CCR as it's ever so slightly less complex (no pure O2 for example). It should be marginally "safer" to dive as there's fewer controls to be confused by. The gas requirements are less difficult to source - basic nitrox is available through membrane compressors.

For those benefits, it is very much a recreational-level unit restricted to recreational depths and doesn’t support accelerated decompression with oxygen rich gasses (e.g. 80+%). The price is considerably more than the equivalent open circuit kit, even twinsets with deco stages. Being a rebreather, it’s far more complex to dive, buoyancy will be harder, flood issues and there's all the essential maintenance faff such as cleaning, building and scrubber packing.

To my knowledge, pure oxygen is possible. The datasheet allows up to 99% for the deco gas. The Horizon comes as a non-deco base version with an additional deco kit that basically contains a second first stage for the deco tank. (There is probably a code to unlock the capability of the computer, I did not figure out yet.) The Horizon has a sort of header or rail for the intermediate pressure gas, to which all tanks (supplier) and all consumers (orifice, solenoid, inflator, bailout 2nd stage) are connected. The setpoint of the deco stage is higher than normal, such that it delivers an elevated intermediate pressure to the header. When you open the valve of the deco tank, the loop will go on deco gas. Of course, you then have to switch the controller to the O2 target fraction for your deco.
 

Wibble

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In essence converting it to a standard CCR
 

rjack321

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Been reading this with interest and can't figure out what kind of diver would want one and be satisfied with it long term - like 4 years from now?
 

Wibble

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Been reading this with interest and can't figure out what kind of diver would want one and be satisfied with it long term - like 4 years from now?

Think that’s most of us. An SCR requires just as much effort to learn to dive safely as a CCR, but with so many restrictions it seems barely worth the effort.
 

rjack321

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Think that’s most of us. An SCR requires just as much effort to learn to dive safely as a CCR, but with so many restrictions it seems barely worth the effort.
I could see the value if I was someplace warm with tons of shallow reefs with lots of skittish fish and a passion for video (but not many or any deep sites)

Where the option was to spend 2 hours on OC and feel all dried out afterwards or 3+ hours on a Horizon and not feel like I'd been to the Sahara. Or where O2 fills were a huge challenge but membrane produced 32-36% (with associated argon fraction) wasnt too insanely priced. So the value curve on SCR shifts for dive site and logistical reasons due to the unique Caribbean island I happen to live on lol
 

Zebra 1

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I just finished the book learning portion for my TDI Air Diluent CCR Diver Course which for some reason includes SCR.
The learning curve is actually steeper on the SCR portion. At least the training gave me a better understanding of why I would not want to dive SCR (except in an emergency).

The entry cost of CC scares away most people and being uneducated about the differences SCR can seem like a viable option. Makes a sale (or 2) for a local dive shop.
 

Wibble

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SCR's there if you've run out of oxygen and don't need to bail out.

CCR's the cost of a motorbike. In some ways that's a capital cost; you'll recoup some of that should you sell it. The larger issue's the training and practice which is also an up-front cost.

It's worth, if you can, doing the helitrox extension. It's an extra dive below 40m/125' and gets you a helitrox ticket to 45m/148'
 

Zebra 1

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After our TDI Air Diluent CCR Diver Course we can take Helitrox CCR or Air Diluent Deco-CCR. What is the difference between the two? I assume the Helitrox course will get us everything the Air Diluent teaches plus Helium. We are working our way to full Trimix, neither of us are OC tech divers (doing our tech on CCR).
 

Wibble

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After our TDI Air Diluent CCR Diver Course we can take Helitrox CCR or Air Diluent Deco-CCR. What is the difference between the two? I assume the Helitrox course will get us everything the Air Diluent teaches plus Helium. We are working our way to full Trimix, neither of us are OC tech divers (doing our tech on CCR).

It's the Advanced Nitrox and Deco Procedures course. Learning about decompression, gradient factors, deco stops, dive planning, reserve gas, gas switching, etc. On OC it's with a single decompression gas cylinder. Helitrox isn't any great difference; less narcosis and a little more theory.

Need someone who's done the CCR version (of ANDP) to give chapter and verse on it.
 
https://www.shearwater.com/products/perdix-ai/

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