FATHOM Dive Systems Q&A

[MattK911]

Hi everyone, I wanted to open up this forum to act as a Q&A for Charlie Roberson and I (Matt Key) for questions involving our rebreathers.
We want to make ourselves available within the ScubaBoard Community, and answering any questions you may have involving our design, philosophy, or anything else related to our rebreather lineup.

In addition to our record-breaking Fathom MK3, we are very excited to announce that our rebreather offerings are expanding this year with our new FATHOM GEMINI. Utilizing our needle valve, line lock system, HUD, potted electronics, and removable scrubber in a form factor that is great for squeezing into small caves, or throwing into a carry-on for your next vacation. While none of these features may be "new", offering all of them in this layout and form factor certainly is.


We look forward to your questions and hearing from this community.

 

[Marie13]

Question about your HUD. I have a new Kiss Spirit but added your HUD separately. Why is the cable so stiff compared with that on my Petrel 3? I pretty much have to tie it down to the loop otherwise it easily comes out of the mount, but it still has a big loop coming out to the side. Wrapping the cable around the loop isn’t successful.

 

[MattK911]

Question about your HUD. I have a new Kiss Spirit but added your HUD separately. Why is the cable so stiff compared with that on my Petrel 3? I pretty much have to tie it down to the loop otherwise it easily comes out of the mount, but it still has a big loop coming out to the side. Wrapping the cable around the loop isn’t successful.

Our HUD is now using the same waterblocked cable used on hardwired Shearwaters, fisher cables, and a few other applications. If your Petrel 3 is on an AK cable (4 pin wet-mateable) the wire is a little more flexible. We originally were using a more flexible wire but switched to "Shearwater Cable" as its much more robust.

I would recommend adding 2 or 3 O-Rings on the loop to hold the wire to the loop. Coil the wire around the loop while routing the cable under the O-rings. We use -128 sized orings to hold the HUD cable to the loop on our backmount unit, and it works well for us

Also what mount are you using?

 

[Marie13]

Our HUD is now using the same waterblocked cable used on hardwired Shearwaters, fisher cables, and a few other applications. If your Petrel 3 is on an AK cable (4 pin wet-mateable) the wire is a little more flexible. We originally were using a more flexible wire but switched to "Shearwater Cable" as its much more robust.

I would recommend adding 2 or 3 O-Rings on the loop to hold the wire to the loop. Coil the wire around the loop while routing the cable under the O-rings. We use -128 sized orings to hold the HUD cable to the loop on our backmount unit, and it works well for us

Also what mount are you using?

Yes, my Petrel 3 has the 4 pin connector.

I’m using a 3-D printed mount from Explorer Technology (Jonah Silverstein). Works fine, except for that stiff cable! Love the HUD other than that cable issue.

Thanks for the info. I’ll go get some of those O-rings.

 

[rddvet]

Yes, my Petrel 3 has the 4 pin connector.

I’m using a 3-D printed mount from Explorer Technology (Jonah Silverstein). Works fine, except for that stiff cable! Love the HUD other than that cable issue.

Thanks for the info. I’ll go get some of those O-rings.

The oring work perfectly. Matt or Charlie I’m sure can get you the exact size. I will be honest. I have the narced at 90 hud that was on the first units. My wife’s died and charlie replaced it with a new hud. The new cable is definitely thicker and less flexible. I personally love mine over my wife’s but that’s just messing with it above water. I’ve never dove it or built my unit with hers to try. She says it’s a non issue, but she absolutely has 2 of the oring that come on the fathom loops to contain it.

Matt, you a should give us more info about you. I’m a fathom diver but we haven’t met and I didn’t know anyone was working with Charlie. Might as well tell us how you got involved. I would also suggest an in-depth video or breakdown of why the Gemini is better than the sw because that’s the question on everyone’s mind. I was going to come by the shop and check it out but I’ve been out of the water a little while and haven’t had to head that way. -Richard.

 

[MattK911]

Matt, you a should give us more info about you. I’m a fathom diver but we haven’t met and I didn’t know anyone was working with Charlie. Might as well tell us how you got involved.

I try to keep a low profile, so I’m glad to see that it’s been working I’ve been diving for 7 years now, worked as a “jack of all trades” in the industry for 5. I finally pulled the trigger on a used FATHOM 2 years ago, and have been working for Charlie for almost a year. To keep a long story short I wanted to cave dive more, and finish my mechanical engineering degree, and it turns out Gainesville is a pretty great place to do both

I would also suggest an in-depth video or breakdown of why the Gemini is better than the sw because that’s the question on everyone’s mind.

We are currently working on getting a walkthrough video, as well as an info page on our website.

 

[PEDiver]

To preface, I only have experience on a chest-mount unit (the Choptima) but am toying with getting a BM unit. How does the WOB compare for the Gemini vs. the BM Fathom unit?

 

[mr_v]

Matt, I enjoyed Fathom. A lot. It is likely to become my second CCR.

What are your thoughts on the likelihood of losing needle valve adjustment during dives? I adjusted the valve 5 minutes into the demo to perfectly match my metabolic rate but kept wondering what could happen if I accidentally brushed against something and lost the adjustment. Is there a way to secure the needle valve position?

 

[grantctobin]

Matt, I enjoyed Fathom. A lot. It is likely to become my second CCR.

What are your thoughts on the likelihood of losing needle valve adjustment during dives? I adjusted the valve 5 minutes into the demo to perfectly match my metabolic rate but kept wondering what could happen if I accidentally brushed against something and lost the adjustment. Is there a way to secure the needle valve position?

That would be wildly hard to brush accidentally. As you said, only took five minutes to adjust.

 

[rddvet]

Matt, I enjoyed Fathom. A lot. It is likely to become my second CCR.

What are your thoughts on the likelihood of losing needle valve adjustment during dives? I adjusted the valve 5 minutes into the demo to perfectly match my metabolic rate but kept wondering what could happen if I accidentally brushed against something and lost the adjustment. Is there a way to secure the needle valve position?

It is completely unneccessary to be concerned about. It is very very unlikely to occur. Even if it does, you're watching your p02 via computer and HUD so you should be seeing a drop or rise in the p02. Never once had an issue. If you're on the unit and the needle valve getting bumped causes a major problem with your p02 that you don't see, the problem is not the unit but the diver. Obviously people get complacent and ignore stuff, but the hud is hard to miss when things go wonky and it's also an mccr which imo the benfit is that it forces you to keep more track of your p02 than in an eccr (though also imo it doesn't matter eccr or mccr, you should be paying attention).