Okay, Ive had my KISS GEM PSCR for a few weeks now and have done a few dives on it since training. Ive had some requests to start a thread about my experiences with the GEM, so here it is.
Lets start with why I chose the GEM. Ive gotten to a point in my diving where my dive time is limited by the amount of gas I can carry. While my RMV is fairly low (.35-.45 range), Ive found myself having to bring along a couple of stage cylinders in addition to my sidemount cylinders. Adding a 3rd stage cylinder isnt really practical, so a rebreather seemed the appropriate solution.
In discussing this with some people, the first response I usually get is, you still need to bring enough bailout to get out of the cave. Im well aware of this, and what those people dont understand is that not all cave penetrations are necessarily linear. In other words, just because Im doing a 3-4 hour long dive in a cave doesnt mean Im 1.5-2 hours from the entrance. Caves are mazes and one can spend a lot of time in the 3000-4000 penetration area. I have swam out of Jackson Blue, average depth 85-90, from 2500 penetration on an AL80 while pushing a scooter in front of me during low flow and still had plenty of volume left in the cylinder. Im diving my GEM on a set of cave-filled LP 85s, one of which is about 1.5 times the volume of an AL80. One LP 85 alone is enough bailout. Add the 2nd one thats plumbed into the GEM and thats more than enough gas to get out from 4000 back in a 90 deep cave a couple of times.
As many of you know, I typically dive sidemount, and not just for the configuration, but also for the passages I dive. One of the key considerations in choosing a rebreather has always been the ability to sidemount it. My reason for wanting a rebreather, as stated above, was gas extension. While I do deep dives on occasion, I much prefer to spend more time diving and less time decompressing. While CCRs can be somewhat advantageous on deep dives, Im fine doing those dives on OC. I needed something that would simply allow me to stay in the 80-100 depth range longer without carrying half a dozen cylinders. When I saw the KISS GEM at DEMA last year, I had found the solution to my problem. The GEM is compact and can easily be mounted in a low profile position with a sidemount configuration. I hadnt really considered an SCR before, but the GEM had my attention.
As I said, the GEM can easily be mounted in a low profile position. I have rigged it up so I carry it in a similar manner as I do a stage cylinder on top nestled in between my right sidemount cylinder and my torso. The GEM is a gas extender. The current mouthpiece is a 3:1, which means it can extend gas 3 times what it is. In other words, the 116 cf in my LP 85 becomes the equivalent of 348 cf on the GEM. Ive heard rumor of 5:1 and 8:1 mouthpieces being produced in the future and was considering getting one, but I dont think that will be necessary. I was able to get an RMV of .128 on my last GEM dive. Ive had as low as .07. Planning on an average RMV of .12, I can get 4 hours from an LP 85, 4.5 from an LP 95. At this point the scrubber becomes my limiting factor, not the mouthpiece.
Ive done rebreather tryouts before, including over an hour diving a KISS Classic CCR, and 15-20 minutes each on a Meg and a Dive Rite Optima. I know most people have issues with buoyancy control when they go from OC to diving a RB. That wasnt an issue for me. I knew what to expect and didnt fall into that with the GEM. I had already experienced it on my KISS Classic dive a couple of times and it was enough to get it ingrained in my mind. The most difficult part of diving the GEM was the work of breathing. Finding the perfect position for the counter lungs has been the challenge. I played around with the position and finally found where I get the least work of breathing. One thing about the GEM is the counter lung covers are small. KISS uses 4 liter MSR bags, but the covers dont allow for full expansion of the bags. My first couple of times on the GEM resulted in pretty significant gas consumption because I had to exhale a little through my nose on every breath, thus causing the GEM to have to pull in more gas during every exhalation. This issue was easily resolved by removing the MSR bags from the covers.
With the MSR bags removed, I moved them around until I found the best place for breathing. Ive also found that I have to retrain myself on breathing underwater. On OC, I typically only take 6-8 slow breaths per minute. Before anyone says it, I dont skip breathe. Im not holding my breath, just breathing slowly. Thats not the way to do it on the GEM. Breathing has to be more like it is on the surface. I was finally able to retrain myself somewhat, but until I have more time on the GEM, it will take some concentration to breathe properly on it, especially since Im still spending more time on OC than I am on the GEM. I may end up putting the MSR bags back in the covers, but definitely without the bungee that are used to retract them.
Another thing I discovered is I tend to fin much like I breathe. On OC, I fin very little, but am still able to swim at a pace of about 50 fpm. During my last GEM dive I noticed I was finning along with my breathing. So my glide was gone! I really had to concentrate to slow my finning down. That will be something else I need to work on. I guess it really doesnt matter for my RMV, but it would be nice to not fin so much. It was making me tired!
I did notice that if I distracted myself I was more likely to fall into my usual slow finning pace and breathe easier. I decided during my last dive to do a little survey work and was able to just fall into the task of collecting data while monitoring my ppO2 regularly. I also noticed my breathing and finning relaxed somewhat. I think more time on the unit will lead to that happening without the distraction.
One of the things I dont particularly like about the GEM is the length of the loop hoses. While I understand the GEM is being marketed to recreational divers and the long hoses may work for them, the length doesnt work for the diving Im doing. Im still working through how I will deal with the hose issue. Its not a pressing issue since I dont plan on taking the GEM into small passage without more time on it.
The nice thing about the GEM is that once I get everything dialed in and more time in it, it wont be an issue to dive in mixed teams. As I said earlier, I have the GEM plumbed into my right sidemount cylinder. I still have a 7 hose on that cylinder and my left cylinder is no different than it is in sidemount. Rather than pulling the 7 hose all the way out and routing it around my neck, I leave it tucked into the retainers on the cylinder and clipped off to my waist d-ring. If I need to donate it, I simply grab it and pull it, breaking the zip tie and pulling it loose from the hose retainers. I still have my left cylinder for bailout.
I also have my GEM plumbed so I can swap cylinders with a quick release. Some people have suggested I use a gas switch block, but Im not sure I really need that. Its simple enough to disconnect from one cylinder and connect to another. That also means I can plumb my decompression cylinder into the GEM at the end of the dive and continue to breathe warm, moist air, even during that portion of the dive. And with longer bottom times, the decompression will also become longer, so keeping the gas warm and moist will be nice.
Overall, Im happy with my decision to buy a KISS GEM. Once I have a little more time in it, Ill be taking it on some of my usual dives and putting it to the use I intended it for when I bought it. The true test will be riding my Magnus without having the mouthpiece fly out of my mouth because of the force on the loop!
Lets start with why I chose the GEM. Ive gotten to a point in my diving where my dive time is limited by the amount of gas I can carry. While my RMV is fairly low (.35-.45 range), Ive found myself having to bring along a couple of stage cylinders in addition to my sidemount cylinders. Adding a 3rd stage cylinder isnt really practical, so a rebreather seemed the appropriate solution.
In discussing this with some people, the first response I usually get is, you still need to bring enough bailout to get out of the cave. Im well aware of this, and what those people dont understand is that not all cave penetrations are necessarily linear. In other words, just because Im doing a 3-4 hour long dive in a cave doesnt mean Im 1.5-2 hours from the entrance. Caves are mazes and one can spend a lot of time in the 3000-4000 penetration area. I have swam out of Jackson Blue, average depth 85-90, from 2500 penetration on an AL80 while pushing a scooter in front of me during low flow and still had plenty of volume left in the cylinder. Im diving my GEM on a set of cave-filled LP 85s, one of which is about 1.5 times the volume of an AL80. One LP 85 alone is enough bailout. Add the 2nd one thats plumbed into the GEM and thats more than enough gas to get out from 4000 back in a 90 deep cave a couple of times.
As many of you know, I typically dive sidemount, and not just for the configuration, but also for the passages I dive. One of the key considerations in choosing a rebreather has always been the ability to sidemount it. My reason for wanting a rebreather, as stated above, was gas extension. While I do deep dives on occasion, I much prefer to spend more time diving and less time decompressing. While CCRs can be somewhat advantageous on deep dives, Im fine doing those dives on OC. I needed something that would simply allow me to stay in the 80-100 depth range longer without carrying half a dozen cylinders. When I saw the KISS GEM at DEMA last year, I had found the solution to my problem. The GEM is compact and can easily be mounted in a low profile position with a sidemount configuration. I hadnt really considered an SCR before, but the GEM had my attention.
As I said, the GEM can easily be mounted in a low profile position. I have rigged it up so I carry it in a similar manner as I do a stage cylinder on top nestled in between my right sidemount cylinder and my torso. The GEM is a gas extender. The current mouthpiece is a 3:1, which means it can extend gas 3 times what it is. In other words, the 116 cf in my LP 85 becomes the equivalent of 348 cf on the GEM. Ive heard rumor of 5:1 and 8:1 mouthpieces being produced in the future and was considering getting one, but I dont think that will be necessary. I was able to get an RMV of .128 on my last GEM dive. Ive had as low as .07. Planning on an average RMV of .12, I can get 4 hours from an LP 85, 4.5 from an LP 95. At this point the scrubber becomes my limiting factor, not the mouthpiece.
Ive done rebreather tryouts before, including over an hour diving a KISS Classic CCR, and 15-20 minutes each on a Meg and a Dive Rite Optima. I know most people have issues with buoyancy control when they go from OC to diving a RB. That wasnt an issue for me. I knew what to expect and didnt fall into that with the GEM. I had already experienced it on my KISS Classic dive a couple of times and it was enough to get it ingrained in my mind. The most difficult part of diving the GEM was the work of breathing. Finding the perfect position for the counter lungs has been the challenge. I played around with the position and finally found where I get the least work of breathing. One thing about the GEM is the counter lung covers are small. KISS uses 4 liter MSR bags, but the covers dont allow for full expansion of the bags. My first couple of times on the GEM resulted in pretty significant gas consumption because I had to exhale a little through my nose on every breath, thus causing the GEM to have to pull in more gas during every exhalation. This issue was easily resolved by removing the MSR bags from the covers.
With the MSR bags removed, I moved them around until I found the best place for breathing. Ive also found that I have to retrain myself on breathing underwater. On OC, I typically only take 6-8 slow breaths per minute. Before anyone says it, I dont skip breathe. Im not holding my breath, just breathing slowly. Thats not the way to do it on the GEM. Breathing has to be more like it is on the surface. I was finally able to retrain myself somewhat, but until I have more time on the GEM, it will take some concentration to breathe properly on it, especially since Im still spending more time on OC than I am on the GEM. I may end up putting the MSR bags back in the covers, but definitely without the bungee that are used to retract them.
Another thing I discovered is I tend to fin much like I breathe. On OC, I fin very little, but am still able to swim at a pace of about 50 fpm. During my last GEM dive I noticed I was finning along with my breathing. So my glide was gone! I really had to concentrate to slow my finning down. That will be something else I need to work on. I guess it really doesnt matter for my RMV, but it would be nice to not fin so much. It was making me tired!
I did notice that if I distracted myself I was more likely to fall into my usual slow finning pace and breathe easier. I decided during my last dive to do a little survey work and was able to just fall into the task of collecting data while monitoring my ppO2 regularly. I also noticed my breathing and finning relaxed somewhat. I think more time on the unit will lead to that happening without the distraction.
One of the things I dont particularly like about the GEM is the length of the loop hoses. While I understand the GEM is being marketed to recreational divers and the long hoses may work for them, the length doesnt work for the diving Im doing. Im still working through how I will deal with the hose issue. Its not a pressing issue since I dont plan on taking the GEM into small passage without more time on it.
The nice thing about the GEM is that once I get everything dialed in and more time in it, it wont be an issue to dive in mixed teams. As I said earlier, I have the GEM plumbed into my right sidemount cylinder. I still have a 7 hose on that cylinder and my left cylinder is no different than it is in sidemount. Rather than pulling the 7 hose all the way out and routing it around my neck, I leave it tucked into the retainers on the cylinder and clipped off to my waist d-ring. If I need to donate it, I simply grab it and pull it, breaking the zip tie and pulling it loose from the hose retainers. I still have my left cylinder for bailout.
I also have my GEM plumbed so I can swap cylinders with a quick release. Some people have suggested I use a gas switch block, but Im not sure I really need that. Its simple enough to disconnect from one cylinder and connect to another. That also means I can plumb my decompression cylinder into the GEM at the end of the dive and continue to breathe warm, moist air, even during that portion of the dive. And with longer bottom times, the decompression will also become longer, so keeping the gas warm and moist will be nice.
Overall, Im happy with my decision to buy a KISS GEM. Once I have a little more time in it, Ill be taking it on some of my usual dives and putting it to the use I intended it for when I bought it. The true test will be riding my Magnus without having the mouthpiece fly out of my mouth because of the force on the loop!