Great writeup for InDepth. After seeing a Gemini at Ginnie in a BM setup, it piqued my interest since I've been looking at BM units (even though the Gemini wouldn't be a traditional BM setup). I just really like the idea of being able to configure the unit with full-size doubles without that much incremental drag (or being able to switch to SM in the future if needed).
Review Fathom Gemini 010
- Thread starter grantctobin
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Underwater Tourist
Contributor
Curious if anybody else who has been diving gemini is interested in doing a review/sharing his/her experience?
I purchased a second hand unit (almost new with just 5 hrs on it) in Mexico and completed the crossover Mod 1 ART at 3D Diving in Tulum. After the crossover I went for cave diving and put about 25 hrs on the unit. My unit came with a BOV from iQSub instead of the classic DSV, something new to me.
I can confirm all the previous comparisons with the Kiss Sidewinder are pretty accurate.
The Gemini is significantly more solid and robust in all respects. The black “amalgon” canisters appear to be a bit heavier than their Kiss SW sintactic foam counterparts, abt 1 kilo each, however this does not affect the overall comfort underwater. This material appears extremely resistant, something I have not seen to date in any rebreather.
The unit breathes slightly better, however my max. depth was 29 M till now, so this is might be subjective.
It is simpler to operate since it does not have an ADV, which IMHO is not really required. The needle-valve dual MAV appears and feels very robust and is a pleasure to operate once the proper tune up has been found. There is no internal schematics available though and I am curious to see it inside out once the service time will come.
Flushing the unit is a very straight forward operation – press slightly the diluent MAV button and release the excess gas through the mouth. At this point I do not feel the need to release the excess gas through the OPV fitted on the counter-lung and I actually did not use the OPV at all, though it’s good to have it there just in case.
The removable scrubbers offer great flexibility. Since all the spit goes into the exhale canister (left one) and there is no water trap of any sort, I feel the perforated net design does a good job in retaining some of the spit out of the sorb, hence after 4-5 hrs of diving the exhale sorb appears less wet than in the Kiss SW.
The built-in HUD is a great addition to safety, particularly since it uses the same well familiar modified Smithers code.
The fact that the head may accept the JJ-CCR coaxial oxygen sensors is really good, since I do not like the Molex connections.
During the crossover I used the Intersorb as scrubber which appeared to produce more dust than the Sofnolime under the same compacting factor. I prefer the Sofnolime so far, but I am really curious to experiment with the Drager DiveSorb in the future.
My next test will be to put it to more respectable depths to asses the WOB, particularly since it comes with an O2 regulator with fixed IP at 14 bars.
The weak points (I am subjective here):
- the plastic zip-ties used for securing the corrugated hoses tend to become loose, I had to renew them after 6 hrs; on the longer run I will switch to coated jubilee clips of marine-grade SS.
- the BOV is rather heavy and after 2+ hrs I feel a bit of jaw fatigue, even though it allows for quick sanity breaths if needed, it is too bulky for my liking, so I will switch to classic iQsub DSV next.
- the operation of inserting the scrubbers into the canisters require a significant force in order to compress the canister o-ring, there must be proper inner lubrication and I believe these o-rings must be renewed more frequently, perhaps 6 months or so.
I can confirm all the previous comparisons with the Kiss Sidewinder are pretty accurate.
The Gemini is significantly more solid and robust in all respects. The black “amalgon” canisters appear to be a bit heavier than their Kiss SW sintactic foam counterparts, abt 1 kilo each, however this does not affect the overall comfort underwater. This material appears extremely resistant, something I have not seen to date in any rebreather.
The unit breathes slightly better, however my max. depth was 29 M till now, so this is might be subjective.
It is simpler to operate since it does not have an ADV, which IMHO is not really required. The needle-valve dual MAV appears and feels very robust and is a pleasure to operate once the proper tune up has been found. There is no internal schematics available though and I am curious to see it inside out once the service time will come.
Flushing the unit is a very straight forward operation – press slightly the diluent MAV button and release the excess gas through the mouth. At this point I do not feel the need to release the excess gas through the OPV fitted on the counter-lung and I actually did not use the OPV at all, though it’s good to have it there just in case.
The removable scrubbers offer great flexibility. Since all the spit goes into the exhale canister (left one) and there is no water trap of any sort, I feel the perforated net design does a good job in retaining some of the spit out of the sorb, hence after 4-5 hrs of diving the exhale sorb appears less wet than in the Kiss SW.
The built-in HUD is a great addition to safety, particularly since it uses the same well familiar modified Smithers code.
The fact that the head may accept the JJ-CCR coaxial oxygen sensors is really good, since I do not like the Molex connections.
During the crossover I used the Intersorb as scrubber which appeared to produce more dust than the Sofnolime under the same compacting factor. I prefer the Sofnolime so far, but I am really curious to experiment with the Drager DiveSorb in the future.
My next test will be to put it to more respectable depths to asses the WOB, particularly since it comes with an O2 regulator with fixed IP at 14 bars.
The weak points (I am subjective here):
- the plastic zip-ties used for securing the corrugated hoses tend to become loose, I had to renew them after 6 hrs; on the longer run I will switch to coated jubilee clips of marine-grade SS.
- the BOV is rather heavy and after 2+ hrs I feel a bit of jaw fatigue, even though it allows for quick sanity breaths if needed, it is too bulky for my liking, so I will switch to classic iQsub DSV next.
- the operation of inserting the scrubbers into the canisters require a significant force in order to compress the canister o-ring, there must be proper inner lubrication and I believe these o-rings must be renewed more frequently, perhaps 6 months or so.
There's no baffle or anything to help with water? I thought there was supposed to be.
I've never been a big fan of the golem/iQsub BOVs. I'm very happy with the divesoft. Its more neutral in the water and I never get jaw fatigue. With the golem there's definite fatigue due to the weight. People say the connections for the golem is far superior to the divesoft, but I've got zero issues with the divesoft connections. I wish Charlie would have stuck with Divesoft as an option for the units
I just came back from Mexico also doing a crossover at 3D in Tulum.
After the class we did some caves, and I now have about 15h on the unit.
I did the class on my own brand new unit, and can second almost anything @GaBitzu said.
I stick with the DSV instead of the BOV, and for me it feels better in the water compared to the BOV on my other RB. (Choosing between DSV and BOV would be a topic on its own...)
For me, the zip ties still work...
Proper lubing is really required on all parts of the unit, tolerances are quite narrow
My biggest (in fact the only) pain point with the unit is the quite short loop hose, which creates a bit of tension on the DSV and almost acts as a gag strap for me.
It is said that WOB is heavily influenced by the wing used. I currently use the Halcyon ZG with steel tanks, which tend to push on the counterlung, as the bottles are attached to the outside of the wing and not on the harness like on other systems. For me, it works really well and I am happy with the WOB, but will try to compare with other wings (xdeep, Razor) in the future.
No, there is nothing. There is an OPV in the CL, which can be used to dump water, but before it has to go through the whole exhale canister. Until now, I did not have any water in after the exhale canister.
After the class we did some caves, and I now have about 15h on the unit.
I did the class on my own brand new unit, and can second almost anything @GaBitzu said.
I stick with the DSV instead of the BOV, and for me it feels better in the water compared to the BOV on my other RB. (Choosing between DSV and BOV would be a topic on its own...)
For me, the zip ties still work...
Proper lubing is really required on all parts of the unit, tolerances are quite narrow
My biggest (in fact the only) pain point with the unit is the quite short loop hose, which creates a bit of tension on the DSV and almost acts as a gag strap for me.
It is said that WOB is heavily influenced by the wing used. I currently use the Halcyon ZG with steel tanks, which tend to push on the counterlung, as the bottles are attached to the outside of the wing and not on the harness like on other systems. For me, it works really well and I am happy with the WOB, but will try to compare with other wings (xdeep, Razor) in the future.
No, there is nothing. There is an OPV in the CL, which can be used to dump water, but before it has to go through the whole exhale canister. Until now, I did not have any water in after the exhale canister.
Indeed there are no baffles. If the diver maintains a reasonable horizontal position throughout, the moisture and spit will accumulate at the top of the left canister without much penetrating the perforated top plate.
I agree the corrugated hoses are shorter than normal, but shorter induces a less drag on gas flow, hence a better WOB. I would consider trying out some 5 cm longer hoses though.
Forgot to mention the wing use vs WOB, indeed it seems to be a connection here. I was told during the crossover that the best setup is reached with the Razor, which I have never tried or used. I use the XDeep Tec ever since. One particular setting on the Xdeep is to attach the counterlung in between the spinal pouches and the BCH itself, instead of attaching it 1st on the diver’s back.
I agree the corrugated hoses are shorter than normal, but shorter induces a less drag on gas flow, hence a better WOB. I would consider trying out some 5 cm longer hoses though.
Forgot to mention the wing use vs WOB, indeed it seems to be a connection here. I was told during the crossover that the best setup is reached with the Razor, which I have never tried or used. I use the XDeep Tec ever since. One particular setting on the Xdeep is to attach the counterlung in between the spinal pouches and the BCH itself, instead of attaching it 1st on the diver’s back.
I managed to dive the Gemini CCR consistently to deeper depths. IMHO the maximum depth for a dive with reasonably moderate effort (no DPV) and extended BT (no bouncing) is 100 M. Furthermore, the maximum depth for a no-effort DPV dive is 110 M. Anything more and the CO2 starts to build up, without being effectively scrubbed. I used for all dives Sofnolime 737 moderately compacted and the maximum gas density was 6.2 g/lt. Perhaps with a lesser gas density the comfort & efficiency can be expanded deeper, but for the moment the helium availability & price has proven to be a serious limitation.
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