Poseiden MK VI "Recreational Rebreather"

[Brendon]

Just wondering what people think of this rebreather and how they feel about it being marketed to recreational (Non-Tech) divers.

http://www.poseidon.com/products/reb...iscovery-mk-vi

[Packhorse]

It is a rec CCR so it should be marketed at rec divers.
Its simply not a tec unit and that is not a bad thing.

[tstormdiver]

My instructor, who used to constantly ride CCR's (in general) into the ground as killing machines, absolutely loves his. He is ate up with it. I am taking a "wait & see" approach to the new Prism2.

[HIGHwing]

It is a rec CCR so it should be marketed at rec divers.
Its simply not a tec unit and that is not a bad thing.

Of course, now that Poseidon has announced additional software configuration options, including decompression, greater depths, and Trimix one has to wonder if those capabilities exceed the hardware configuration. Some could say the unit's design is not superior to other available units on the market for nearly even money. This keeping in mind that you must replace the module at $400 retail, plus training for each new software capability.

[bullshark]

Just wondering what people think of this rebreather and how they feel about it being marketed to recreational (Non-Tech) divers.

Discovery MK VI | Poseidon

Just wondering what people think of this rebreather and how they feel about it being marketed to recreational (Non-Tech) divers.

Discovery MK VI | Poseidon

I really like the system. As a photographer and fish behaviorist, it is exactly what I want. This page is more helpful. Down the right side, you can find links to the PDF Manual, which will tell you much more about the units theory and philosophy.

There are two things that keep me from buying it:

1) Reliance on Poseidon for service

Poseidon makes fine gear, but here in Florida (at least) it has a reputation for difficult to non-existant service along with very spotty parts availability. The control head in this unit counts time in weeks and demands inspection by Poseidon service techs every 2 years (104 weeks). Certainly things like solenoids and regulators need to be looked at and serviced at such intervals, but I'm not willing to accept unreasonable delays or incur large shipping expenses to get it done.

2) Operating expense

I haven't looked that hard, but the prices I found for the pre-filled Scrubbers looked to be around $40 each. Lasting just 3-4 hours and my diving every weeked, that's just way too much money. My OC gas cost for a 2-tank is about $12. I can probably afford the outlay, its just the principle of the thing. How self-indulgent must you be to quadruple your operating costs on top of laying out a Kings Ransom for the equipment to do it with?

They really need a user-refillable cannister (at least one diver has made his own). Traveling with rebreathers is difficult but possible. Many destination have O2 and Sofnolime. Finding supply of these pre-filled units is just not very likely to coincide with the locations I want to dive.

If it were one or the other, I might take it on, despite the 9K outlay ( device + training ), but both together just make it too much to take on for this diver.

[HIGHwing]

Regarding operating expenses, it depends on how you're going to use the MKVI, or perhaps any rebreather. Admittedly, startup expenses do vary, but the MKVI can easily be purchased for $6,800 or less, and the training is averaging about $750 plus PADI materials. The training can escalate if you want the advanced class which includes the use of bailout gasses and allows deeper depth.

Your earlier concerns assume you'll be purchasing a MKVI straight away. According to your profile you're in Fort Lauderdale which places you reasonably close to Silent World, who has units on the shelf available for diving - today. In addition, right after DEMA, SeaExperience's owner reported a serious interested in placing two of them in his rental line after the remodeled Fort Lauderdale shop is completed this January. This is all positive information for you as you can get the training, and rent the units with relative ease right in your backyard before deciding to purchase.

Per dive cost somewhat depends on what exactly you're going to do. Afterall, if you use one liter of oxygen per minute, well that's what you use. If you're already paying $12 for an airfill, you're actually paying more per dive in gas cost by a significant margin. My two 13 cu/ft cylinders generally give me four one hour dives on a single fill (no drysuit). Assume you pay $48 (4 fills X $12) for a day of Open Circuit Diving in a standard Morning 2-Tank and Afternoon 2-Tank. If I take my CCR along to be your dive buddy, I'm only paying a gas bill of $12.32 plus Florida tax for the whole day of diving (using FillExpress.com's current posted retail gas rates).

Now, let's address the issue of the scrubber. I have spent $13.00 in gas for the four dives, and now I have to buy a $33 scrubber so I'm in it for $46 plus tax. The scrubber appears a non-issue to me.

Now being slighly more practical as the above is not representative of how I actually dive my CCR. With the limited cost of adding 4 cu/ft of helium to the diluient, I almost always run a 21/35 diluient instead of air. By choosing this diluient and assuming I manage it properly, I shorten my deco time, significantly decrease gas narcosis, and can go to the gas depth limit without any [measurable] additional cost per dive. I personally believe it's important to rid myself of any narcosis on the rebreather as staying sharp is necessary, so again I use Trimix. Using FillExpress.com retail rates, I calculated the gas fill for four Steel 100s of 21/35 at $160 to make the equivalent OC dives on 21/35, and I'm not even bothering to calculate the OC deco gas because we'd need SAC rates, dive profiles, etc. What's really important is that during the ascent you will eventually use the deco gas you bought whereas I will use the onboard gas in the O2 tank for decompression and in most cases (admittedly not all) I'll be waiting for you to finish breathing that expensive gas while hanging on the line.

Open Circuit and Closed Circuit are two distinctly different tools. You have to decide which tool is most appropriate for you. That said there is no way a CCR costs more per dive than Open Circuit - no way - no how. My wife dives her OC Tec Rig right next to me on my CCR in Lauderdale frequently, and I cannot WAIT for her to make the switch because the OC rituals that include hauling tanks, using dive weights, and large gas bills sucks.

When I bought the O2ptima, I calculated the number of Trimix fills in a set of doubles it would take to break even - it doesn't take as long as you might think once you start enjoying helium like the DIR people do.

The question becomes, will that 100 Steel with whatever mix you choose give you the runtime I can get? If you ever start calculating the cost of a dive by cost per minute then CCR becomes quite handy. The one-hour drop given by the Captain on a 120-foot deep wreck is now 53 minutes of bottom time and 7 minute ascent for $3.00 in gas versus a fill in the blank SAC rate multipled by gas cost on Open Circuit.

Howard Packard was quoted as saying the bubbles of every Open Circuit Trimix dive he ever did were shaped like dollar signs. He STILL claims not to be able to explain it, but SWEARS it to be true.

[Ramsy]

I dove a MK VI during one of Poseidon's demo days a few months ago. I did not have any real issues with the unit. In fact, diving in total silence was a weird feeling. The biggest thing I noticed right away is that you no longer have the ability to use breath control to control buoyancy. So, that is something you have to get used to and re-learn from diving open circuit.

I do agree that the cost of use is high on these units. The Poseidon reps did say tell us that the scrubbers should be changed after every 3 hours of use, but that time could be extended to 6 hours depending on the diver and gas consumption. The reps acknowledged that the scrubbers are quite expensive, but Poseidon will be working with their dealers to try and reduce the price.

My personal issue with the MK VI and it being marketed to the recreational community is that I fear that future users of the MK VI will never understand the mechanics of the unit, fail to maintain the unit correctly and/or fail to maintain the unit at all which may lead to injury or death. The reason I have this belief is because Poseidon markets the MK VI as being fully automatic. When it powers up, the MK VI runs 55 or so independent diagnostic tests to make sure the unit is running properly. If the unit passes these tests, according to the Poseidon reps, you should feel confident in diving the unit. During the dive, if the computer senses a malfunction, the red light in front of your mask will light up. If that happens, you should then go to open circuit immediately. Poseidon also markets the paddle on the MK VI as being the only "computer" you now need when diving. It functions not only as your dive computer, but as the MK VI system computer.

With rebreathers, in my opinion, I think anyone who dives them needs to at least understand the principles behind it and how their rebreather works so that they can deal with and hopefully be able to correct any issues that might arise before it becomes a lethal issue. With the MK VI, by making it specifically tailored to the recreational community, Poseidon is removing the "mystery" of the art of how a rebreather works by simply telling the customer to not even worry about how it works because their system is 100% fully automatic. If the system passes all tests at power up, you can safely dive the unit. And if there is a failure during the dive, with the flip of a switch you can go open circuit. However, if you don't have AL 80 tanks attached to the MK VI with sufficient gas in the tanks and are at a sufficiently deep depth, you might not have enough gas to safely get back to the surface on open circuit if the need arises.

In sum, with the MK VI being marketed as being fully automatic, I worry that recreational divers who dive these units may not fully appreciate the risks because they don't understand the intricacies of how their rebreather works, will rely too much on the fact that the unit is 100% automatic and be lulled into a false sense of security.

[HIGHwing]

It is being marketed as fully automatic and self-contained to sixty feet. Sure the BOV is nice, but you're absolutely correct that beyond 60 feet you must take bailout gas to assure your return to the surface. Hard to say that an AL80 is or isn't the most appropriate choice in the absence of a dive plan. I tend to find 100 feet an AL30 works, 140 feet an AL40 works, from there it gets more complicated.

[bullshark]

HIGHWing:

Thanks for the update on local availability. Last I checked it was only down in the Keys. Not doing 3mix, not interested in doing 3mix. So your economies will never apply to me, nor is the MK VI intended for it. I hear rumors, but I believe Manufacturer data. Meanwhile , I still don't know anyone that gets warm fuzzies when trying (emphasis on trying) to get their Poseidon regulators serviced. It may have improved some in the past few years but not enough to ever see the things out on a boat. I see rebreathers more often than I see Poseidon regulators.

Still faced with the scrubber cost being $40. It will easily run 4 hours or more in tropical waters (the 3 hour rating is at 15C). So the big question is "Will the scrubber keep overnight?". If it doesn't, then its $40/day vs $12 (not even counting O2 and cleaning supplies).

The OC 3mix diving started looking like $-signs the minute you signed up...10K worth of stuff and training, that needs 500/year in maintenance even if you don't dive...lets not forget the "discount" 3-mix divers get when they go out for dives to use it...

You forgot to add the 35.00 scrubber to your wreck dive. I would do it on Nitrox and get the same 60 minutes of no deco profile [you said 7 minute ascent], perhaps more because I will be running higher PO2 on the deep leg. It would cost me $6 vs your $38, and I would enjoy the dive and not worry about taking drugs (Helium) to be extra vigilant, since I don't have to worry that my rig may try to kill me. (c:

So tell me true: Suppose you do a dive on Saturday afternoon with a fresh scubber; just an hour or so. If you have another dive on Sunday morning, do you change the scrubber, or will it keep overnight?

[bullshark]

It is being marketed as fully automatic and self-contained to sixty feet. Sure the BOV is nice, but you're absolutely correct that beyond 60 feet you must take bailout gas to assure your return to the surface. Hard to say that an AL80 is or isn't the most appropriate choice in the absence of a dive plan. I tend to find 100 feet an AL30 works, 140 feet an AL40 works, from there it gets more complicated.

I didn't see any 60 foot limitations in the manufacturer data though that might be a guidleine for some...
From the manual:"The MkVI Discovery is certified to a maximum operating depth of 40 meters (130 feet)."

I would be perfectly comfortable with 3L (HP) of air/nitrox dil for bailout on any recreational dive. It doesn't take much gas to do a normal ascent and safety stop. That's one of the features/benefits of the system. I'm not all niggled up with He or ordinarily running deco obligations.

The system determines that you need to go OC, it tells you (Audible, vibrate, display&LED) and your buddy; you flip to OC on the mouthpiece and the decompression computer knows about it. You surface, fix the problem if you can, and go back to diving with no loss of information. An HP 3L is about the same as a 30, but it will be missing a little from buoyancy/dil duties.