What do you love and what do you hate about your unit?

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I have owned a number of different brands of rebreather as well as practically every iteration of the Meg. I presently dive a Tiburon and so far it is my favorite. I ordered mine with the minnow counterlungs which I am still undecided about but I have 2 other megs to borrow CLs from if needed
 
And not a single negative? Hmmmmm

When I first got the unit there were several minor things I found frustrating because I was used to diving other units and tried to adapt the Fathom to that method. One day I had an epiphany and said "just dive it like Charlie intended" and it's been great since then. Regardless, here's my cons list.

1. I'm not a huge fan of the valves being up. I have had that situation where I was wearing thick undergarments and accidentally rolled my inflation bottle off and needed a buddy assist to get that fixed.

2. I'd like the loop to run left right rather than right left so that the optional ADV was feeding fresh gas into the diver rather than into the scrubber.

3. It's a good idea to re-adjust the set screws on the needle valve once every few months. It's not a big deal and takes 30 seconds to do, but it's just another maintenance item.

4. The nylon line locks will swell if you put them in a ziplock bag over night, making it nearly impossible to install them in the head. If you're traveling to a remote destination, it's not a bad idea to have a few spares.

That's really about it.
 
Oh, let me add a 5th item. There's only one CL size. This only impacts smaller people.
 
When I first got the unit there were several minor things I found frustrating because I was used to diving other units and tried to adapt the Fathom to that method. One day I had an epiphany and said "just dive it like Charlie intended" and it's been great since then. Regardless, here's my cons list.

1. I'm not a huge fan of the valves being up. I have had that situation where I was wearing thick undergarments and accidentally rolled my inflation bottle off and needed a buddy assist to get that fixed.

2. I'd like the loop to run left right rather than right left so that the optional ADV was feeding fresh gas into the diver rather than into the scrubber.

3. It's a good idea to re-adjust the set screws on the needle valve once every few months. It's not a big deal and takes 30 seconds to do, but it's just another maintenance item.

4. The nylon line locks will swell if you put them in a ziplock bag over night, making it nearly impossible to install them in the head. If you're traveling to a remote destination, it's not a bad idea to have a few spares.

That's really about it.

Funny, I like the valves up on the bottles, though I've never dove valves down so I don't have any other reference. I have found that I'm ever so head heavy due to the valves being up and the thor's hammer on the head, but I've moved to heavier fins than my slipstreams

Do you know why he chose to go right to left? I assume there's a reason. I believe I was told he chose to have the adv go into the scrubber so it would mix in the head and get analyzed by the cells immediately. Not sure how true that is.

On the line locks I started using weed whacker line that has an edge on the side (not just round) and I find it works a little better than the round stuff. Never seen swelling. That's weird. Was it after salt or fresh water?

Oh, let me add a 5th item. There's only one CL size. This only impacts smaller people.

We were actually surprised when buying that there wasn't a small size. I think Chelsea's probably the smallest person currently diving the fathom and she uses a short plate and has no issues with the counterlung size that she knows of.
She's also obnoxious because she's yet to have to move her needle valve off of the "off" setting. At it's most closed it's the perfect flow for her metabolism if not almost slightly too much.
 
@rddvet if you think about a fathom as an improved Meg mCCR, then it follows the same convention as the unit that he based it off of. That had adv on the exhale long to give better dil flushes, but also to have the O2 right at the divers mouth for hypoxia mitigation, but also to keep with the convention of right to left flow from the double hose regulators that the navy divers still train with.
@kensuf probably has a more direct history from Leon on why, but that was what was explained to me by my instructor as the logic which makes perfect sense.
 
I'm a new rebreather diver myself and chose the Fathom as my first rebreather. So far I love it.

Some positives:

* Build quality is very high and everything on the unit feels extremely durable.
* The unit trims well and feels similar to set of doubles in the water.
* I found the concepts behind diving mccr fairly easy to understand and matched my personal philosophy of keeping everything as simple as possible (no electronics besides ppO2 monitoring).
* Charlie is very helpful and responsive to questions

Some negatives:

* I dive the unit in DIR configuration with backmounted lp50s, and it's a bit cumbersome on land. LP50s, being round-bottomed, like to slide around. A stand would be good in this regard. It's fine on boats where the benches have a back, but gearing up on a picnic table or anything else without a back requires a friend to hold the unit. This isn't a problem with the stock configuration, though.
* I too find the loop fiddly to screw in sometimes, though I think I've gotten better at it, but it does take some care.
* Early on I had some difficulties calibrating the unit and found myself wishing there were something like a pressure pot I could put the head in to make calibration easier. However, with some practice I've gotten better at calibrating so I may not care about this for much longer.
* The loop hoses have stretched a bit and I may shorten them at some point.
 
@flymolo I put boots on my 50's in the rack, though if you use 3l's behind the 50's similar to the GUE JJ config, then you get get it to stand up if you set the heights right.
I will say that the bayonet connections from IQ Sub as used on the xCCR, Defender, Hammerhead, etc. are AWESOME and way better than the screw in connections. Would be awesome if Charlie used them. More expensive than screw in, but so much nicer.

Does the head not have a head cal kit available or would it not work? The pressure plates that you can get for the Liberty that actually let you test it up to 3ata I think? at least 2, but I think more, that let you get your O2 cal, linear deviation, and cell limiting in one fell swoop is really slick. Perks of really complicated electronic sets with all the pressure sensors required to do it, and it actually does it all automatically from the solenoid. One of the issues with the Meg style heads though is the top plate is pretty thin so it can't take a whole lot of outward pressure and I recall hearing from @Bobby I think of several of the early ones cracked from positive pressure in the can.
 
@rddvet if you think about a fathom as an improved Meg mCCR, then it follows the same convention as the unit that he based it off of. That had adv on the exhale long to give better dil flushes, but also to have the O2 right at the divers mouth for hypoxia mitigation, but also to keep with the convention of right to left flow from the double hose regulators that the navy divers still train with.
@kensuf probably has a more direct history from Leon on why, but that was what was explained to me by my instructor as the logic which makes perfect sense.

Originally I was looking at the SF2 but for many reasons became uninterested. Then it was between a Meg and the JJ, but then the Fathom came out and it had everything I liked about the meg, with some pluses. I didn't know anything about the history on the Meg.

I'm a new rebreather diver myself and chose the Fathom as my first rebreather. So far I love it.

Some positives:

* Build quality is very high and everything on the unit feels extremely durable.
* The unit trims well and feels similar to set of doubles in the water.
* I found the concepts behind diving mccr fairly easy to understand and matched my personal philosophy of keeping everything as simple as possible (no electronics besides ppO2 monitoring).
* Charlie is very helpful and responsive to questions

Some negatives:

* I dive the unit in DIR configuration with backmounted lp50s, and it's a bit cumbersome on land. LP50s, being round-bottomed, like to slide around. A stand would be good in this regard. It's fine on boats where the benches have a back, but gearing up on a picnic table or anything else without a back requires a friend to hold the unit. This isn't a problem with the stock configuration, though.
* I too find the loop fiddly to screw in sometimes, though I think I've gotten better at it, but it does take some care.
* Early on I had some difficulties calibrating the unit and found myself wishing there were something like a pressure pot I could put the head in to make calibration easier. However, with some practice I've gotten better at calibrating so I may not care about this for much longer.
* The loop hoses have stretched a bit and I may shorten them at some point.

I agree the loop hoses are also a little long. I've been tempted to cut it down 7 corrugations that Jon Bernot suggested, but can't bring myself to do it. I'll be buying the shorter hoses when Charlie has them officially available.
 
Since everyone is chipping in on the fathom I will also. Like everyone else I'm very happy with it. This is my first season on any unit and I don't have any significant complaints. I will echo though what @rddvet said about getting the loop hoses on the head. If it takes me 10 minutes to assemble to the unit about 6 of those are getting the hoses screwed on without cross threading.

I dive where its cold (bottom temp was 41F last weekend) and the ADV shutoff is a pain to get to with thick everything on but I know other units also have it on the interior side of the loop. It did make me a little jealous of the XCCR guys though. For reference I usually keep the ADV on descending a line but turn it off once my depth has stabilized.

I occasionally use the GUE/wreck setup and in those instances a stand would be really nice. I actually use that configuration less than i probably should just because of how much of a pain it is to keep stable on a table in rocking seas.

The counterlungs work for me and WOB hasn't been an issue at all coming from a long time on OC. I go head down a lot and haven't had any issues being head down for extended periods of time. My wife is also probably in the running (at worst maybe silver or bronze medal) for smallest person on the unit and I think a smaller counterlung would probably have helped her out but it hasn't been a deal breaker for her either.

Again though - its a breeze to setup, its simple to troubleshoot, and I like not having to fiddle with much during a dive. Once I'm in the water it just works, fading into the background, and that's all I can ask from the unit. Don't take what I said above as complaints - those are minor annoyances. The needle valve life is great. Not worrying about a solenoid is awesome. The build and attention to detail plus Charlie's responsiveness to questions has been above expectation. I'm a happy customer. I looked hard at the XCCR and JJ for a while but ultimately found stacking how I dive against the three units the fathom made the most sense. It may not for others but it did for me and it works where I take it.
 
@flymolo I put boots on my 50's in the rack, though if you use 3l's behind the 50's similar to the GUE JJ config, then you get get it to stand up if you set the heights right.

Good thought- I've been thinking about putting boots on the 50s myself, although it feels a bit...dirty :wink:. The 3L o2 bottle I mount behind the 50s is upside down so I have to be careful about leaning the unit back onto the o2 regulator, and I'm not sure if the boots would help given the weight distribution with the o2 bottle piggybacked on. I'll probably just order a couple boots and give them try anyways.

@flymolo I will say that the bayonet connections from IQ Sub as used on the xCCR, Defender, Hammerhead, etc. are AWESOME and way better than the screw in connections. Would be awesome if Charlie used them. More expensive than screw in, but so much nicer.

Interesting. If they're anything like the bayonet style connectors I have to attach my BOV to the loop, that would be awesome.

@flymolo Does the head not have a head cal kit available or would it not work? The pressure plates that you can get for the Liberty that actually let you test it up to 3ata I think? at least 2, but I think more, that let you get your O2 cal, linear deviation, and cell limiting in one fell swoop is really slick. Perks of really complicated electronic sets with all the pressure sensors required to do it, and it actually does it all automatically from the solenoid. One of the issues with the Meg style heads though is the top plate is pretty thin so it can't take a whole lot of outward pressure and I recall hearing from @Bobby I think of several of the early ones cracked from positive pressure in the can.

There is no head cal kit available, though with enough demand I'm sure there could be. It would be good to have a cal kit and cell checker all in one, if that's possible. But again I'm not sure if I'll still want one after more time.

I agree the loop hoses are also a little long. I've been tempted to cut it down 7 corrugations that Jon Bernot suggested, but can't bring myself to do it. I'll be buying the shorter hoses when Charlie has them officially available.

Yeah, I'm looking forward to those. I will probably opt for them too.
 
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