Prism II or Se7en?

[kensuf]

Every CCR on the market today has trade-off's -- no single CCR does everything perfectly. When choosing a CCR you should ask yourself some questions to help you make a more informed choice.

Start with the incredibly basic first question: why do you need a rebreather?

Then ask what kind of diving environments will you be using that rebreather in?

Also you may consider asking yourself if you are planning on traveling with the rebreather? If so, are you planning on going to exotic/remote locations, or places where access to things we take for granted (Fed-X) is not an issue?

Use some of these questions to begin the process of identifying what features are important for you in a rebreather.

Personally, due to the increased risks involved in diving a CCR, I would never choose a CCR on price alone. Having said, there are some great CCR's that you can find at bargain basement prices that will work well as a first CCR -- I just saw a KISS Classic sell for $1500, and while it was missing bells and whistles, it's a great starter unit (I have over 250 hours on them, they're good beginning machines).

I'd strongly recommend Bozanic's book on CCR's, "Mastering Rebreathers," to give you an idea of some of the things you can look at with a CCR.

 

[tbone1004]

@kensuf I just saw a Pathfinder going for $3k as well which is a nifty unit.

@guruboy the ability to use solid state O2 sensors is already available for the Prism. You have to buy the CPOD and M28 and it can monitor the sensors. It can't drive the solenoids, but you may find that you don't want to blindly trust the computer to maintain your setpoint in favor of a hCCR upgrade, or just run the unit manually with the solenoid as a parachute. The cost of upgrading to the M28 with the SS sensors is going to be quite steep. As it stands, we don't have a date or cost to do that upgrade, but I would expect the end of this year at the earliest but likely early 2018, and an upgrade cost of at least $4k, likely $5k. It will require being sent back to the factory or the service centers for the upgrade. It requires a new O2 board in the head itself, it's not something you can just drop right into the head in place of the current cells. The new board should be backwards compatible with the galvanic cells, but it still requires a new board. M28 will be required as well, so it's not going to be a cheap upgrade.
Currently that service center in the US is Jeurgensen Marine who has not exactly made a lot of people warm and fuzzy with their service time, cost, and politeness. It is enough for me to avoid that unit alone.

The Prism II currently uses the Shearwater DiveCAN which is arguably the best eCCR electronics set on the market. You cited as not being able to support the SSS which is not true. The DiveCAN is a digital system and is able to accept a myriad of different upgrades. Those boards need to be designed by Shearwater and the CCR manufacturers no differently than the existing O2 boards. Poseidon plans on releasing these sensors to the wild after they have the CPOD's out and all of the Se7en's upgraded, so expect early 2019 before they're available to the public, and depending on how this Huish acquisition goes, we'll see how quickly they respond to getting an upgrade path, but 2019 is realistic for an option to go to SSS for most of the DiveCAN rebreathers on the market. Can't guarantee, but it's likely to happen for most of the units in a pretty timely manner provided that all of the early testing goes as well as we are hoping.


now, all of that said. What are your answers to Ken's questions? Why do you need or want a rebreather?

 

[guruboy]

Adding the CPOD and m28 is the same cost for either ccr, so not a factor here.

Neither CCR can be upgraded to SSS at the moment, so again not a factor here. As it is, they currently use the same galvanic O2 sensor.

 

[guruboy]

As for Ken's questions, it's just another gadget to use in my diving. I don't need it for anything but technology is improving and prices are dropping enough to consider trying it.

 

[tbone1004]

@guruboy you say the SSS is not a factor but it sounded like you were using that as your main reason to lean towards the Poseidon.

What is the price of the two units that you are looking at?

What is your ultimate goal for the CCR in your diving?

 

[guruboy]

@guruboy you say the SSS is not a factor but it sounded like you were using that as your main reason to lean towards the Poseidon.

What is the price of the two units that you are looking at?

What is your ultimate goal for the CCR in your diving?

SSS is a nice to have. The fact that Poseidon is releasing it first is a nice bonus since I expect they would add it to the se7en sooner rather than later (hopefully, compared to other brands). Not a deciding though factor since it won't be usable anytime soon. I in no way implied it was the main reason to lean towards the se7en. I'm not leaning towards anything yet.

My goal is to just try it and have fun diving a different way. Maybe TEC down the line but no set timeline for that.

 

[tbone1004]

@guruboy do you know if it's nice to have though? Does it outweigh the potential cons of that unit?

2 cell vs 3, cartridge scrubber vs packable, non-standard electronics, unproven computer, unproven sensors, etc.

Is a ccr really the right decision or does a SCR make more sense? Is eCCR the best way to go right now, or do you buy an inexpensive mCCR like the KISS that @kensuf was talking about, really learn how to dive it, and then in a year or two if you decide you can justify going to CCR and make a more informed decision

 

[RainPilot]

@guruboy do you know if it's nice to have though? Does it outweigh the potential cons of that unit?

2 cell vs 3, cartridge scrubber vs packable, non-standard electronics, unproven computer, unproven sensors, etc.

Is a ccr really the right decision or does a SCR make more sense? Is eCCR the best way to go right now, or do you buy an inexpensive mCCR like the KISS that @kensuf was talking about, really learn how to dive it, and then in a year or two if you decide you can justify going to CCR and make a more informed decision

The 2 cells vs 3 is a feature not a bug. It is a different paradigm from voting logic, the arguments for and against are legion but comparing them based on number of O2 cells is not fair.

I use a packable scrubber in mine.

Non standard is an odd term in CCR electronics, I dare say even some identical units from some manufacturers aren't standard with each other.

Unproven computer, Richard Pyle and co spent a looooong time doing a lot of BIG dives on these units, the CisLunar pedigree is pretty solid as well.

Unproven O2 sensors? I assume you are referring to the SSS. The existing sensors are the same as any other unit around.

 

[tbone1004]

@RainPilot that's why I said potential cons.

Packable scrubber is aftermarket and not factory authorized. Again, no issue with it, just a potential con

nonstandard being that it is a proprietary electronics system vs. basically everyone else moving towards the Shearwater DiveCAN. pros and cons of that as well

The M28 is still unproven, and the current paddle is too limited in function for many, but also not compatible with the SSS.

The SSS sensors were what I was referring to

I actually have no major issues with the Se7en, but I wouldn't choose it over a Prism II unless there was a massive cost savings or I had a particular reason to need it. Keep in mind, I love Poseidon, and I really don't like Hollis, so it's not a brand bias either

 

[kensuf]

There's a lot of nifty thought in the Se7en electronics package and the dual sensor verification system is kind of cool. I can see a couple of instances where that could break down, but those would be caused by user error.

And that's the crux of the biggest problem with rebreathers. Human error.