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  1. #1

    Default FATHOM CCR Review

    Fathom CCR Review

    Author with Fathom rebreather before a recent dive at Madison Blue Springs.

    FOREWARD/DISCLAIMER: In the interest of full disclosure, Charlie Roberson, the designer of the Fathom is a good friend and dive buddy. My unit, No. 003, is one of the first generation units made and I did get a ?keyman? discount on the unit for being an early adopter. However, I have no financial interest in the success of the unit or any other skin in the game apart from wanting to see a friend do well selling what I think is a great product. I originally wrote this review back in 2016 but never ended up publishing it, since I wanted to wait until the Fathom was ready for public release. The Fathom CCR made its debut at the 2017 DEMA show, with the new Gen. 2 head with integrated HUD and I felt the timing was right to share my opinions and experiences with this unit. ? Bob


    I guess it was time to get a rebreather. Ok, let me back up, start at the beginning.

    I started cave diving and quickly found the advantages of diving a ?Hogarthian? backmount cave diving setup in terms of simplicity and streamlining. Based on my experience, the more simple and streamlined your gear is the more enjoyable and safe your diving will be. After a few hundred cave dives in that setup I became interested in exploration opportunities that demanded a sidemount configuration. Applying the things I learned from all those backmount dives, I put together what I felt was a simple and streamlined sidemount diving setup. Low pressure 120 ?water heaters? cranked with ?cave fills? gave me a lot of gas to do a lot of diving. I had a set of manifolded 120s for the deep trimix dives and a set of sidemount 120s for the shallower stuff. I moved from Gainesville to Tampa so I was farther from the springs and closer to ?the deep stuff.? Unfortunately once you leave Cave Country finding trimix on tap can be very difficult, and filling for a weekend dive became a one or two week plan in advance affair requiring lunchtime escapes from the office, but I managed.

    I was reluctant to make the move from open circuit to rebreather diving because I had a little bit of ?goldilocks syndrome? about the units that I was seeing at the dive sites and that friends were diving. Most of the people I saw diving rebreathers looked like they were working awfully hard dragging ponderous rigs through the water with hoses, counterlungs, canisters, cases, and other assorted ?stuff? jutting out all over the place. I had a list of ?must haves? and there was nothing I saw out there that was ticking all the boxes. I wanted something simple. I wanted something streamlined. So I watched as new units came and went with interest, but nothing ever gave me that ?gotta have it? feeling. Then about a year ago one of my main dive buddies, Charlie Roberson, showed up for some Madison Blue Springs exploration dives with something very unusual ? a home-made closed circuit rebreather he designed. He called it the Fathom CCR and watching the unit perform in the water I quickly got that ?gotta have it? feeling. I watched with interest as he used the Fathom CCR on some very impressive cave dives to Madison Blue Springs, Cathedral Canyon, Twin Dees, Lineater Spring, and many more.


    Fathom developer Charlie Roberson in Cathedral Canyon.

    I?ve known Charlie since law school and he?s always been the extremely meticulous and procedural kind of diver that some people can?t appreciate but everyone needs in a dive buddy during any serious dive. I think if you?re going to be successful at this hobby you need to be a ?gear nerd? and obsessed with optimizing how your gear is configured and why. Charlie definitely has that meticulous nature in spades, and it shows in the Fathom CCR rebreather. The build quality is stellar without a burr or blemish to be found (until I started taking it diving and putting them on there). The design is simple and streamlined.

    The Fathom mCCR is simple. There are no electronic solenoids injecting anything into the rebreather that can fail open, fail shut, or give you too much or too little gas. There are no batteries that drive the rebreather than can quit. Oxygen addition is manually controlled by a needle valve built into the manifold that passes through and hangs at your right D-ring. Having worked at a couple fill stations this was super intuitive to me, it?s just like controlling the needle valve on an Oxygen tank and watching the analyzer respond when filling banked nitrox. Only instead of putting it in an array of bank bottles, it?s going into your breathing loop. When you dial it in and it matches your metabolic work load it is almost like magic underwater. Twist it up until your set-point stabilizes, dial it down if it?s climbing, tweak it a little during the dive, shoot a little extra O2 in when you need to bump it up - simple.

    Diluent addition is controlled by a manifold that passes through and hangs at your left D-ring. There?s a QC-6 female connector that you plug your off-board diluent into. I have pairs of sidemount configured LP120s, LP85s, and LP50s that I have filled with appropriate gases to cover the gamut of dive profiles. Push the button and the diluent goes into the canister. I also opted for the Automatic Diluent Valve (ADV) as this helps with descending and it makes maintaining minimum loop volume a piece of cake.

    For electronics I opted for the Petrel 2 EXT with Fischer connector, I route the computer onto my left forearm where my analog compass used to reside. Since it?s backlit it?s easy to read while scootering without the need to illuminate it with a light. I also opted for the hardwired HUD that uses the Smithers Code to display ppO2. One amber or green blink and I know I am at my preferred 1.0 or 1.1 ppO2. When I start seeing more blinks or red lights it means I need to fiddle with my needle valve or make gross adjustments with the O2 or Diluent additions.

    The Fathom mCCR is streamlined. The back mounted counterlungs keep the critical workspace clear of clutter. This is great for giving you space to work on survey, clip off stages, maneuver your scooter, and slide through restrictive passage.


    Photograph of the author showing the clean front profile of the Fathom mCCR.

    I dove an Optima rebreather and while the front mounted counterlungs were not as frustrating as I expected, the Fathom back mounted counterlungs are noticeably cleaner. The standard fathom configuration has a suit and wing inflation cylinder mounted to the canister on the left while the oxygen cylinder is on the right. Mounting these cylinders ?valves up? means I use the same backmount diving muscle memory I?ve developed over the years.


    Valves up configuration on the author?s Fathom mCCR.

    Having all the ?complicated? parts of the unit up top I think puts everything in the place where it is easiest to reach to free line entanglements. Moreover, having the heavy valves and regulators up there helps put weight where you need it to maintain a proper ?knees up? trim position. The ?line lock? system eliminates latches that can snag or be damaged.

    So, having found a rebreather that finally gave me the ?gotta have it? feeling, what would justify the expense of buying a unit and getting trained on it? I once did the calculations and even if you do deep trimix dives every weekend, any rebreather will take a significant amount time to pay for itself in savings on gas fills. Well that comes back to the biggest reason why I finally made the decision to move from open circuit to rebreather diving: the time investment involved in getting gas fills for open circuit diving. If you are regularly doing trimix dives, the time spent advance planning and filling open circuit bottom and decompression mixes rapidly becomes a major chore and time sink (unless you have a home fill station, which, incidentally would probably cost as much or more than a rebreather). Using the rebreather will allow me to do multiple dives on the same sets of tanks and reduce the volume of and hassle of trips to the dive shop ? many more places can quickly top off a suit inflation bottle with air and squirt some high pressure oxygen into a rebreather bottle on short notice than whip up some high pressure 10/70 into a set of LP120s, to say nothing of the accompanying array of decompression mixes. Even if you aren?t doing the deep stuff, if you?re doing long weekends in the backwoods of Florida bringing one or two spare sets of inflation and oxygen bottles will let you eliminate 4-5 hour round trip visits to the dive shops after a long dive day ? time better spent preparing for the next day of diving and around a campfire with friends, food, and beverages.

    Having decided to take the plunge, I told Charlie I had to have one and asked him to build me a Fathom CCR. While the Fathom parts were on order and the units were being assembled I started my rebreather training with Jon Bernot at Cave Country Dive Shop, doing initial rebreather dives on a Dive Rite Optima rebreather. This was my first experience with the bubbleless world, and Jon was a great and thorough instructor. While the Optima was a fine rebreather and a very easy unit to dive, the electronic O2 addition was a nice feature but not right for me. I also wanted to run offboard diluent, which would need some creative hose routing and modifications to run on the Optima.

    My dive buddy Anthony ?Strazz? Strazzulla, who I took all my original cave and tech classes with a decade ago, signed on board as he wanted to get back into rebreathers (he had sold his KISS Classic years ago) and saw the advantages of the Fathom CCR.


    Strazz with his Fathom mCCR.

    Once our units (Nos. 003 and 004) were delivered we met at Cave County Dive Shop for the first Fathom CCR course. The course was unique in many ways. It was the inaugural course for a new rebreather unit and recently approved by IANTD. Jon Bernot and Ted McCoy (who previously taught Anthony?s KISS Classic course) co-taught the course. Charlie attended as well, making this probably one of the most well-appointed rebreather classes you could ask for in terms of top-flight rebreather instructors, leading cave explorers, and even having the designer/manufacturer of the unit in attendance.


    Fathom assembly and lecture at Cave Country Dive Shop. Left to Right: Charlie Roberson, Ted McCoy, Derek Ferguson, Jon Bernot, Bob Schulte, Anthony Strazzulla.

    Throughout this article I have gone through many of the advantages of the Fathom CCR. There are many more advantages and things I like that I could go into great detail on - the work of breathing of the backmounted counterlungs is great, the flood tolerance and recovery is great, the assembly is simple and intuitive - on and on. These things all flow from the fact that the Fathom mCCR is a cave diving rebreather and it was designed that way from the ground up by an active Florida cave explorer. Charlie incorporated the procedures used in real world cave exploration on multiple cave diving projects into the design of the Fathom CCR. Part of the Fathom CCR instructional program is exposure to and discussion of this holistic philosophy of what a cave diving rebreather needs, what it doesn?t need, and how it needs to work.

    There?s nothing groundbreaking about a new rebreather diver gushing about how great his latest purchase is, however I strongly believe the Fathom CCR is groundbreaking in the way that Charlie has distilled some of the best ideas and features out there to come up with a fantastic rebreather for cave diving. I think it?s a great option for cave divers looking for a rebreather that places emphasis on simplicity and streamlining.

    For more information on the Fathom CCR:
    FATHOM Dive Systems, LLC
    jcr@fathomdive.com
    https://www.facebook.com/FathomCCR/
    (352)213-6575

    As a close to this article, I will give a ?loadout? of what components/options I am using my Fathom CCR:

    ? Faber FX-23 O2 and Inflation Tanks
    ? Narked @ 90 HUD hardwired
    ? Petrel 2 fischer cable connection
    ? Hammerhead heavy loop hoses on the head with superfabric covers.
    ? ATS Backmounted Counterlungs
    ? ADV with Omniswivel in-line shut-off.
    ? Flexible loop hoses to the BOV.
    ? Golem Gear Shrimp BOV with Drager Safety Retention Mouthpiece
    ? Halcyon 35 CCR Wing
    ? Halcyon Stainless Steel Backplate with Loop Bungies and prototype Ring Buttplate (Light Monkey now sells this as the Bailout Attachment System)
    ? Left bailout/drive tank: Atomic Aquatics regulator w/ QC6, OPV, and SPG
    ? Right bailout/emergency tank: Atomic Aquatics Regulator w/ Atomic Aquatics 2nd stage, QC6 to LP Inflator ?dongle?, and SPG.

    Safe diving, and I?ll see you at the springs.


    Author on Fathom mCCR. Photo Credit: Michael C. Barnette.


  2. #2

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    A Pelagian, if the Pelagian were made in a first world country. I like it.


  3. #3

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    I have not dived the Fathom, but I have heard nothing but good reports on it.


  4. #4
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    Quote Originally Posted by JohnnyC View Post
    A Pelagian, if the Pelagian were made in a first world country. I like it.
    The Pelagian is a great unit but there are some significant differences with the Fathom CCR, which has back mounted counter lungs, radial scrubber, etc. The biggest difference though is that the oxygen first stage on the Fathom CCR is blocked or uncompensated. This makes the unit much easier to dive and eliminates the need to adjust the needle valve with depth changes. We addressed the depth limitations that come with an uncompensated first stage by using a stronger spring and increasing the intermediate pressure. From the factory the unit has a depth limitation of 400 fsw and can be adjusted in the field to go to 600 fsw.

    Charlie

    J. Charles Roberson
    FATHOM Dive Systems, LLC
    jcr@fathomdive.com

  5. #5

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    Quote Originally Posted by jcr View Post
    The Pelagian is a great unit but there are some significant differences with the Fathom CCR,
    Charlie
    That's what I mean by being made in a first world country.

    The Pelagian has BMCL's, but I'd kill for it to have a removable radial scrubber. I'm not sold on the blocked 1st stage though. I don't mind tweaking the needle valve a touch. I like the ability to throw any first stage on it in a pinch without having to take one apart to steal the spring.

    I do like the Fathom though. I think the options are great, and it looks much more refined. I like the needle valve and instant cell validation concept. I'm glad it's being used in a more polished unit. Definitely doesn't look like it was made in a garage in Thailand


  6. #6
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    Why did the op take an optima class first then the fathom course? Is there only a crossover course currently?


  7. #7

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    Quote Originally Posted by rddvet View Post
    Why did the op take an optima class first then the fathom course? Is there only a crossover course currently?
    The first run of Fathoms was not yet produced with some engineering pieces yet to be finalized and I had a class going and an O2ptima for Bob to dive. It was for general CCR knowledge.


  8. #8
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    Quote Originally Posted by jebernot View Post
    The first run of Fathoms was not yet produced with some engineering pieces yet to be finalized and I had a class going and an O2ptima for Bob to dive. It was for general CCR knowledge.
    So a fathom course does or will exist for a first time rebreather diver?


    Sent from my iPhone using Tapatalk


  9. #9

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    Quote Originally Posted by rddvet View Post
    So a fathom course does or will exist for a first time rebreather diver?


    Sent from my iPhone using Tapatalk
    Yes it exists.


  10. #10
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    Divers interested in either a full course or crossover certification should contact Jon Bernot at Cave Country Dive Shop in High Springs, Florida. Fathom CCR certifications are issued through IANTD.

    J. Charles Roberson
    FATHOM Dive Systems, LLC
    jcr@fathomdive.com


 

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