A Personal View on Different CCR Units

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Updated 24/11/15 (Major) 

What I think

 (for what its worth)!

This is my view and my view only on the pro's and con's of different units and as such I expect to be "flamed" from all directions. I have noticed that as a retailer I have seen far to many customers buy gear which is either total rubbish and/or inappropriate for the type of diving they intend to do. My aim with this piece is to try and stop that happening to potential CCR divers.

Before we go any further I would strongly advise that anyone thinking about buying a CCR should purchase Mel Clarke's book.

CCR Simplified Manual (MOD 1) by Mel Clarke

Please hit the link above for more details.

I would also strongly advise anybody that is even slightly thinking about buying a CCR to watch this very short but very informative clip put out by the RoSPA in the UK .

CCR Aware

Let's now set up a framework for us to work within and, again I expect to be flamed over what I consider as basic concepts that in my view need to be understood and worked over before purchasing a unit.

Why do you want a CCR ??? Some people just want the latest and greatest which is fine but others want a unit to fulfil certain diving tasks, like longer bottom time, access to deeper wrecks or reefs etc. Each unit should be individually assessed for all of the tasks you require of it. Every unit you look at will have good and bad features, very rarely will one unit cover all your needs. You must make sure you have defined what it is you want to achieve, then look at each unit with these requirements very much in mind.

Last of all please be aware that if you won't be diving the unit at least several times a month then just maybe this is not the area for you to be looking at, you must keep diving these things, if only to keep your skill levels up to scratch.

Can you cost justify a CCR ??? The old saying is if you have to ask the price then you can't afford it. Some people think this is correct with CCR units and to a certain extent I agree. It is not an area that you go into on a small budget, though having said that I have seen some very good bargains and some very good home made versions walk through the shop doors over the years. Generally speaking though owners fall into two types of people, the guys that tinker and the guys that like to turn the key and go, this will have a huge bearing on just what unit you you select.. 

You can cost justify a unit but, only in a limited fashion, I like to tell my customers that when starting out you can roughly say that if a dive on OC gear costs you $10 then the same dive on CCR will cost you $20. This covers the consumables and the servicing of the unit. Now once you bring Helium into the equation then we have a whole new ball game to consider and several 10 day trips away diving the unit on Helium will more than give you a great return on your investment. BUT is that the type of diving for you ????

What type of CCR design is for you ??? Now we get into the old water and electronics argument, as you know water and electric just don't mix ..... or do they? We also now touch on the concept of control over the unit, do you want the unit to "fly" itself or do you want manual control? These are serious questions that sometimes also get mixed up with the cost of a unit when making a choice. I am a "trust the electronics" type of bloke, you don't see me wearing a parachute on a plane. I also think that one must further realise that you only get what you pay for in life, so cheapness can have a price attached to it in the long run, payment just might not be in dollars.   

What should you pay for a unit ??? Once you have worked out what type of diving you are doing and what level of trust you place in technology then you are a long way down the path of selecting a unit for yourself. The final hurdle to jump is cost, what are you going to fork out to achieve your diving ambitions.

Cost has a huge bearing on the type of unit you select, and the first question is do you go second hand or brand new. There is nothing wrong with  second hand units and for many of us it is an excellent way to get into CCR diving BUT .... always that but, you must ensure that the unit is functional and safe. I strongly advise that you have someone inspect the unit prior to the purchase. Now should that person be someone like us (SXD), that will inspect and then service the unit or someone like an experienced CCR diving friend ... your choice but please inspect the unit fully first.

Now we get into another  interesting area, cost is reflected in how modern or current your unit is. I look at units like the APD Vision units and see a second generation CCR with all the bells and whistles factored into the cost of the unit. It comes with everything you need to go diving already factory fitted, like harness, cylinders, wing etc. but it also comes with a fully functioning dive computer. We offer units only as full package deals, which include the training, some manufactures/retailers don't. You need to workout the real landed and fully trained cost of your potential unit. Some units come with just the bare bones and once you start adding things like harness, wing, cylinders, dive computer, freight, customs fees and taxes then a cheap unit can be very expensive. .... Do your sums first!

First, second or even third generation (?) units ??? A first generation unit is a unit without any "smarts" attached. Examples would be the Meg, the Inspo Classic, the Kiss, the rEvo and the Paliegan. These units come as base models without any thing other than PPO2 monitoring and maybe some form of PPO2 control provided.  They were the "first cab off the rank" units that have been left somewhat behind in their original format. Now to be fair, all these units can now be purchased with third party control systems and dive computers either factory fitted or added later on. The Meg which has developed its own control system but, can use the Shearwater control system which can be added after market, so does the rEvo and the KISS. Some of these old units may also be fitted with VR Technology control systems (now out of business so avoid), so they have the potential to be a second generation unit of sorts. I tend to look at these units as 1.5 gen units, given that true 2nd gen units have been designed from the floor up with such control systems already in place. 

The one exception to this would be the Optima, this unit was first released as a hotch pot of bits and pieces cobbled together to resemble a CCR ..... I didn't like it one bit. The unit had  and still does have Hammerhead electronics, which makes this a 3rd party add on in some ways.   After saying that I feel that slowly as newer models are released the unit is becoming better and better and is now a true 2nd gen unit.

True 2nd gen units were the early Vision units from APD, the Sentinel and Ouroboros from VR Technology (now out of business but can be found in disguise as the  RedBare CCR -  from VMS - Vobster Marine Systems

The Poseidon MkVI discovery is what I would like to term a 2.5 gen unit, it has fully embraced the concept of full electronic control like no other unit, though having said that I really don't like the early releases of this unit - steer clear of them. 

"I recently completed a training course for a student on a current model of this unit ... I stand corrected, the unit worked just as the manual said it would. In fact all but the problem that you still can't see the HUD has been addressed."

The new Poseidon MkVII unit is a much better version that offers a far greater depth range but again it's not quite there. The cost of a upgrade is outrageous and I strongly suggest you leave this unit alone until it has proved itself in the future. Poseidon has released at DEMA 2015 a new handset and computer system for these units - we are still waiting to see this available. It looks very nice and can be installed on non Poseidon units also but at this point no one in Oz has one.

Please note though I still have seen no evidence that the support will be any better and I find the company to date without doubt the worst manufacture I have ever had to deal with. This still holds at 26/02/20.

We saw two new units emerge from Hollis (Oceanic). The Prism 2 and the Explorer.  The Prism 2 is just a revamped Steam Machine Topaz Prism 1 unit. This unit was a leader 15 years or more ago but fell by the wayside due to very poor manufacturing, the unit was just not well made. The new Hollis unit seems to have addressed these problems but it still is a "tarted up" Prism. Too little done to late to make this a serious unit.

Now the Hollis Explorer is something new and would be well on its way to being classed as a gen 3 unit.  As Hollis states

 "The unit is neither a fully closed circuit Rebreather nor a pure semi-closed system, but an intelligent hybrid that utilizes the best of both worlds. Its compact, lightweight and extremely easy to use." 

It's basically a nitrox ( >40%) single gas unit aimed at the recreational market. It fits into the PADI "rec" specifications and will appeal to the basic recreational diver. The main downfall with this unit is the cost and the limitations it brings to progressing your diving beyond the recreational level - to put it simply you can't ! So I have to ask the question why would you pay an awful lot of money for a unit that will not grow with you.

As expected - gone out of production in 2019  - waste of money am afraid.

Third generation (?) units are here ??? 

Very recently 06/09/14 on wards units  that use the Shearwater controller system have been forced to adopt the new DiveCan systems they now produce. This covers units such as the JJ, rEvo, Optima and Prism2 ... what is DiveCan and should I care ???

Basic answer is yes because it is the way of the future for CCR units

Information supplied by Shearwater - warning technical in nature

Digital communications are clearly replacing analog communications in computer based devices. Since more digital communication is coming into use in rebreathers, Shearwater went in search of the best digital solution. We looked at basic serial and at higher level serial like HDLC and SDLC. We looked at microprocessor communication protocols like I2C and SPI. We looked at internet protocols like Ethernet. We looked at process control protocols like DeviceNet and Modbus. We looked at vehicle protocols like CAN, MilCAN, and NMEA 2000.

In the end, the extremely robust CAN protocol won. It can operate in very electrically noisy environments like a car or semi-trailer. It is suitable for high speed device control like brake-by-wire in cars and turret aiming in tanks. It allows very long cable lengths for surface control applications. It has predictable latency with high traffic, unlike Ethernet. The protocol handler is built into the hardware of the ARM microprocessors that interest us, and the cable level transceiver handlers are inexpensive and used by the millions by the automotive industry so will always be available. Finally, CAN was designed to be a platform that would be used to support a message structure like NMEA 2000 or J1939, and that was exactly what we wanted.

DiveCAN® is a communications protocol consisting of a physical layer and protocol layers. It is based on the industry standard CAN bus that is widely used for cars, boats, trucks, tanks, and factory networks. The physical layer is very robust so it works well even in environments that are electrically noisy. It is suitable for high speed device control like brake-by-wire in cars and turret aiming in tanks. In short, it is widely used, simple, and reliable. The connection is digital and error checked. It is either received correctly, or the error is detected. 

Networking a diving system makes sense for many of the same reasons that networks are used in other applications. It allows modules to be replaced individually as required. If a handset fails, it can be replaced simply in the field. If new technology comes out, it is relatively easy to just unplug the old device and plug in a new device. This ability to upgrade to new technology as is becomes available is another key advantage of the DiveCAN® bus.

There is another benefit that isn’t strictly part of CAN, but is part of DiveCAN® and many other CAN implementations. It is relatively easy to add two more wires and provide power on the bus. This means that power sources don’t have to be in the same place as power. It also allows for backup power schemes and batteries outside the loop powering devices inside the loop.

In life support applications, the modularity can be useful as well. Rather than having a monolithic device that calculates decompression, manages a graphical display, monitors sensors and incorporates other functions, devices can be split out into modules. In the case of Shearwater’s typical DiveCAN® implementation, the module that manages the solenoid is only tasked by reading the sensors and firing the solenoid. It has no complex duties and simpler systems are easier to verify and validate.

Since DiveCAN® devices are independent and mutually suspicious, data logging can be expanded. While one of the devices still maintains the typical dive logs, several devices now may keep a log of DiveCAN® messages which give a very complete picture of actual system operation for analysis.

Each rebreather has either two independent DiveCAN® buses, or a DiveCAN® bus and some other secondary. On systems that have two DiveCAN® buses, one DiveCAN® bus is the control bus and the second is the monitor bus. The control handset needs to know what other DiveCAN devices to expect. A missing device could very well mean an unsafe configuration (i.e. trying to start a dive without the solenoid controller communication to the handset). The handset must be configured for the rebreather. This means that the controller is not interchangeable between manufacturers. For example, an rMS system has to know to look for the scrubber temperature sensors and display an error if they aren't present. 

Although limited to manufacturer approved configurations, this is still more flexible than previous hardwired analog systems.

The Monitor bus is more open to reconfiguration. For example, a NERD, the new DiveCAN LED HUD, or a secondary Petrel DiveCAN handset can all be swapped freely and are generic among all manufacturers, except ISC who have their own connector and bus messaging. A common DiveCAN connector is being used by the rEvo, JJ, Hollis, SF2 and O2pitma, so monitor bus devices are compatible.

Shearwater announced our intention to offer DiveCAN® systems at DEMA in 2009. We shipped our first DiveCAN® systems in 2012 and are now concentrating our rebreather controller research and development on DiveCAN® devices. The DiveCAN® NERD is a recent addition to the list of DiveCAN® devices.

Soooooo more info for the tech head

Essentially the DiveCAN®  is a 2 bus system which lives in the CCR's head.  The control bus (SOLO board) has the DiveCAN® Petrel controller plugged into it via the 5 pin DiveCAN® connector.  The handset will establish the desired setpoint and is the device to use to calibrate the O2 sensors but the actual calibration and solenoid control live in SOLO board and not the handset.  So if the handset should fail, flood – whatever, the control bus will recognize the failure and drop to a setpoint of 0.7 as it has lost the depth information and can’t tell if it’s maintaining the chosen set point.  It will revert to what is knows is a safe set point.  The display bus (OBOE board) has the LED HUD plugged in and will continue to provide secondary display information. The SOLO and OBOE share the O2 sensors but the data buses are not connected so are fully independent.


Devices will not function correctly unless plugged into the correct bus.  Only control bus devices like the Petrel controller will communicate with the SOLO board.  The LED HUD will not function correctly if plugged into the SOLO board, nor will the DiveCAN® NERD display function as a setpoint master. We use the colour coding to distinguish between the 2 buses.

The Divecan concept is again a bit of a waste - great concept but none of the manufactures that have adopted this approach have allowed the units to talk to one another and they remain proprietary systems and the devices are not interchangeable - great opportunity missed. 

What units would I buy or recommend ??? Without question I would recommend the APD range of units to anyone that wants a middle to top of the range unit. This unit will do whatever you want it to do right up to 150m plus dives. APD is the market leader by far and as such you should have no real problems getting service / spares / training worldwide.

09/09/14 ... APD announce their own HUS or NERD system 

Nov '15 ........ They have now upgraded the Vision handset with the new 20/20 version - nice !

The other unit I would highly recommend is without question the JJ-CCR, these are very good units that are suited to the more advanced type of diving.  In my view this manufacturer's units are well worth a long serious look at.

The JJ-CCR  comes as a 2nd gen unit factory fitted with Shearwater controls. The JJ-CCR is without doubt the best unit I have dived to date and is presently my own diving unit of choice. Bang for your Buck the JJ-CCR is superb value and comes fully fitted out ready to dive straight from the box.  This unit is far outselling all other units we retail.

Sept '14 update: Now fitted with the DiveCan system

The Hammerhead,  I have no serious direct experience with  but again  it looks a very good unit and would be worth a serious consideration. Support in Australia will be a major issue. SXD provide training on this unit and will support it in a limited manner.

24/11/15  .... This unit is getting interesting and the way it is marketed has changed somewhat. The unit is now sold directly from a outfit in the US called SubGravity, so training is different and service seems to have improved BUT it is still a back to US solution for serious problems - no real support in Oz. The unit itself is made in the Czech Republic by a company called X-CCR. The quality of this unit is now greatly improved and is becoming a serious player due to the Czech companies influence.  Still no support though in Oz.

The Paliegan is the odd one in my current list of units I would consider owning and to be honest I have very little real knowledge of the units functionality. I  spoke with them at Oztek11 and may well undertake some training on the unit but until then I can't really give any serious comment. Being based in Thailand does not give me a warm feeling about support etc.

The Optima is, as I said looking better and better but I would not recommend this unit based on the local support available in Oz. To be honest this is a shame as I feel that this unit has potential and is being held back by poor service locally. 

Sept '12 update: I now cannot in all honesty recommend this unit based on support and training in Oz. 

Sept '14 update: Now fitted with the DiveCan system

The Poseidon is now another unit I would recommend in its present new and improved form.  Though the local support is still woeful (was the same company providing support for the Optima but now has been changed) and in my view the Swedish head office support is even worst. ..... One to watch though.

Sept '12 update: The distributor for this system has now changed for the better one hopes but the price is way too high for such a limited unit.

June '14 update: Same old same old, a OC scuba supplier taking on a CCR with no skill set or CCR knowledge ... predictable results.

Jan '15 update: New Mrk Seven released - it seems to be an attempt to correct the old problems in the Mrk VI. It has not done this but it does appear to be a base for future changes.

Nov '15 update: First of the improvements are starting to flow. They have now released a new M28 dive Computer and new handset system.

The Jetsam units are solid and as their name (KISS) suggests are basic and simple. Good all round units that will suit the manual/non-electronic person very well. Watch the new Gem .. a SCR unit from Jetsam, could be interesting and ready for modification to a bailout or side mount unit. ...... I have completed a training programme on this unit and would not recommend it for recreational diving  ... wait a year or so for this one to develop.

Sept '12 update: These units have now dropped into the "why would you bother" category  the support in Oz is non-existent and the Kiss units just have not progressed. In regard to the Gem, after the course I cancelled my order. 

In the case of the rEvo family of units they are a 1st gen unit in their base configuration but can be upgraded to a 2nd gen units very easily by adding Shearwater controls BUT this bumps the price way up and subsequently does not make it a good "bang for your buck" option. The unit has quite a few inherent problems that are not being resolve and is passed its prime as a cut edge unit. In short needs a revamp to be serious.  

Sept '12 update: The distributor for this system has now also changed and is located in Melbourne. The main issue I have with these units is the lack of any means to recover from a flood and the price. They have though updated the scrubber monitoring systems and are now worth watching if only for developments in this area. To configure the unit as a full 2nd gen unit is very expensive compared to say a JJ. I would not recommend this unit over an Inspo or a JJ. 

Sept '14 update: Now fitted with the DiveCan system

The Hollis Prism II  ... as of Sept '12 this unit is the new kid on the block ??? Not really, this unit is just a revamped Prism Topaz. A lot of the Prism's problems have been resolved but it is still basically the same old technology, nothing new. Would not recommend this unit at this stage. Hollis and VR Technologies have sort of jumped into bed together and one can expect changes to emerge from this union. Watch out for the Prism III ... I think that will be very interesting.  

Sept '14 update: Now fitted with the DiveCan system

 tag ... why bother ???

The X-CCR ... this company, IQSub makes the guts of the Hammerhead for Juergensen  Marine. The quality of this build is very very good and anything coming out of this factory will be a key player. Their unit has one main advantage over the Hammerhead being that it does not use its electronic's but they have developed their own.

                                       Watch this unit !

The Liberty ... this unit is made by another Czech company Divesoft. The unit is well built but seems to have been built for a strange market. The problem is that the unit is not really aimed at the "Tec" marketplace, the designers have simply ignored what the customers wants. Having said that the unit is in itself a fine unit but would have been so much better if they had back mounted c/lungs, the capability to take any sized cylinders and of course been a whole lot lighter. Obviously this unit has been designed with future new features in mind but currently is just not what the majority of people want from a CCR.

The final family of units are the VR Technology units.

VR Technology went bad and have been bought by Avon for their technology .... be careful when looking at these units until the dust has settled.

June '14 update: Avoid them ... that simple


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