Question Fathoms MK III

[Tobias24]

Hello, is anyone here willing to share their experience with the Fathoms MK III rebreather? I'm considering diving with a JJ or a Fathoms. Currently, I'm a bit more impressed with the Fathoms; I like the lack of electronics. I'm from Europe, and the device isn't really widespread here yet.
I'd be particularly interested in a comparison between GULE JJ and Fathoms.

Thank you.

 

[rudytuhbooty]

I am about to hit 100 hours on mine this weekend and still love it. It's about as simple and robust as possible from an engineering perspective. There really isn't much on it to break that you couldn't fix with generic (other manufacturers)/ commercial (hardware store) parts. The head is potted so even flooding it won't damage anything. I have both the cave config and the tech rig which is setup like the GUE JJ and both are great.

 

[DiveLikeAMuppet]

Fathoms look nice (seen it, never dived it) but you really want a unit that is common in the region and dived by other people, to be able to ask questions and get spares and service. I think the only Fathom distributor in Europe is Techwise on Malta and they probably don’t keep too many spares around, it’s not a large shop.

Stock JJ is really nice

 

[inquis]

I like my Fathom a lot -- bulletproof construction and very simple maintenance-wise. (Outside of lubing o-rings and swapping out sensors, I haven't had to do anything in the 2 years I've had mine.)

I think the biggest difference from a JJ is mCCR vs eCCR. An mCCR appeals to me (my call whether to add O2 when going over a rock), as does a needle valve (less tweaking compared to an orifice). A radial scrubber is less prone to overbreathing/breakthrough in my view. The Dil addition port blows on one of the cells for rapid sensor validation and condensation mitigation.

 

[Seameadow]

I sold my JJ and replaced it with the Fathom, despite not having local Fathom support. The fact is there is just so little to go wrong and most of the machine, you can just user repair or replace a part if needed. No batteries to change etc.

A lot of your decision making would be around your philosophy of eCCR vs mCCR and whether you want to simplify.

I think which one is "better" will be personal preference aspect rather than a technical / operational consideration.

Local instructors and training will certainly play a role, especially if you are starting your journey.

The Tech / GUE type setup can easily be done on either machine, but it should be purpose driven and the best tool for the "job", for your kind of diving, rather than just driven by an idea or philosophy, if that makes sense. Otherwise you will have a sub-optimal solution for your kind of diving.

Although both machines are good I can honestly say I think Charlie went a bit further in literally finding the best possible way to complete every single process on the machine, whether it is the radial scrubber direction which very slightly improves the efficiency, the dil port on the cell as mentioned or materials for example, he did an amazing job. (Personal opinion).

 

[kensuf]

Hello, is anyone here willing to share their experience with the Fathoms MK III rebreather? I'm considering diving with a JJ or a Fathoms. Currently, I'm a bit more impressed with the Fathoms; I like the lack of electronics. I'm from Europe, and the device isn't really widespread here yet.
I'd be particularly interested in a comparison between GULE JJ and Fathoms.

Thank you.

Both the Fathom and the JJ are great units. Both have pros and cons, but the bottom line is you can't go wrong with either one. I owned a JJ for a year and a half, the only reason I sold it is because they wouldn't let me become an instructor on one due to instructor saturation in my area (there are 3 JJ instructors within 50 miles of me). Obviously, I still own a Fathom (two posters in this thread have worked with me for their mod1 or crossover courses to the Fathom).

I personally think an mCCR is better for cave diving because we rarely have square profile caves, I personally prefer eCCRs for deep wall dives. Having said that, I would have zero qualms using a Fathom on deep wall dives or a JJ on cave dives. The bottom line really is if you want the simplicity of an mCCR and a radial scrubber, Fathom is the answer but if you want an eCCR and an axial scrubber, then JJ is your way to go.

 

[boriss]

Hello, is anyone here willing to share their experience with the Fathoms MK III rebreather? I'm considering diving with a JJ or a Fathoms. Currently, I'm a bit more impressed with the Fathoms; I like the lack of electronics. I'm from Europe, and the device isn't really widespread here yet.
I'd be particularly interested in a comparison between GULE JJ and Fathoms.

Thank you.

I did a try dive with 3 CCR's years ago, you can read my experience here: Just tried 3 CCRs (Fathom, rEvo, Choptima)

JJ is much more common, which is great from a support perspective, but it's also heavy (the base unit is about 15lbs heavier, before adding tanks/consumables). Both have "GUE" configurations. Unless you already dive CCR's, you may not have a preference about eCCR vs mCCR yet.

There are tradeoffs with any unit you choose, so go with what you feel you'll like best. People tend to like what we have . Unless you have specific "mission" requirements, it's just a preference call.

 

[rddvet]

I absolutely love my fathom. Search my posts here and you will find my previous comments because I don't want to leave a super long post. I am on Bonaire for the 3rd time diving my CCR and I was discussing it with the two guys at Technical Dive Services today because the owner is on the path to become an instructor and his other instructor is about to cross over to it. My wife and I have fathoms 18 and 19. I believe they're in the 180s now. When I think of the conversation I had with both the guys at the shop, the thing that kept coming out over and over again was reliability and low maintenance. I literally tapped wood at the shop when I said it, but I have not changed a single o-ring in either unit in the 7 years we've owned them. I have never done any major maintenance or repairs on my unit. My wife had to have her hud replaced because she had the narced at 90 fathom originally sent with it and hers died and Charile replaced it for free with his newest fathom hud. She had the diaphragm on her adv get a cut in it, but the new fathom comes sans ADV. Other than that I have had no issues. The only complaint I have is that the unit comes with Apeks regs and we have had about 10 high pressure seat failures. Thank god it seems like it was an issue with service kits because its been a few years. But honestly I switched regs to halcyon regs because I don't need to the strong spring. I have no plans to go past 300ft.
My biggest recommendation is get a second can. Get both configurations. One can with the standard setup for onboard inflation via 3L or al 20s(I think they're 20s I cant remember anymore). And get one can with the full tech setup for onboard 50s, 3L oxygen, and 3L infaltion. I will go back and forth. In Fl caves I'm diving 50s and bring stages. For very long penetration dives I will change to sm bailout and sm85s plus stages. Here in Bonaire, 3L O2 and inflation setup, al40 bailout. The two cans allow you to just move the head back and forth for the dive you need to do. 100% worth it. I also recommend the 5lbs scrubber unless you're really doing some serious ass dives.
I have tried a few other units and none impressed me like the fathom. I liked the JJ and the XCCR, but the simplicity and reliability of the fathom wins hands down for my diving.
I will now go knock on wood 30 times since today was my first day on island so tomorrow is the first dive day and I just said I have never had any issues with my unit and don't maintain it.