Diving my Kiss GEM rebreather for a year

[scubaab]

I have been diving my GEM rebreather for a year, and thought it would be nice to let people know what it was like to learn how to dive it and what problems and solutions I encountered during this time. I know in Rebreather years I am still an infant, but the experiences might help people. Here is the link to my blog post:The Kiss GEM Rebreather ? The Undiscovered Voyage

 

[mselenaous]

Nice write up. I recently got certified to dive the GEM and had a great time. It took a bit to get used to the counterlungs and hoses, but it was doing long dives. I am looking forward to more practice!

Happy Diving!
Elena

 

[scubaab]

Thanks mselenaous. Yes those counterlungs are sometimes a pain. I also had some issues with buoyancy in the beginning. But now I love diving the GEM. Out in the ocean again this weekend

 

[Dirty-Dog]

So as an Official Hoover who would love to extend bottom time, this looks awesome. I don't know that I currently get to dive enough to make the expense worthwhile, but it still looks awesome.

As with other OC divers, I'm accustomed to making small changes in buoyancy with my lungs. How is this done with the GEM?
Why do you say that the GEM is unsuited for deco diving?
What sort of provision do you have for OC bailout when diving the GEM?

 

[bankyf]

Anyone considering the purchase of a GEM should check out the classified section ASAP. Ron (Deepthought) is a very honest and reliable guy and you can be sure that anything he has for sale is in great condition. He is almost giving that GEM away if you figure in what the Petrel costs. I very seriously considered purchasing this, but with two CCRs (one of which I purchased used from Ron) and not enough time for either, it just didn't make sense for me to add a PSCR in the mix. I have no personal or financial gain in the sale of this GEM, just trying to pass on a great deal.

So as an Official Hoover who would love to extend bottom time, this looks awesome. I don't know that I currently get to dive enough to make the expense worthwhile, but it still looks awesome.

As with other OC divers, I'm accustomed to making small changes in buoyancy with my lungs. How is this done with the GEM?
Why do you say that the GEM is unsuited for deco diving?
What sort of provision do you have for OC bailout when diving the GEM?

 

[scubaab]

So as an Official Hoover who would love to extend bottom time, this looks awesome. I don't know that I currently get to dive enough to make the expense worthwhile, but it still looks awesome.

As with other OC divers, I'm accustomed to making small changes in buoyancy with my lungs. How is this done with the GEM?
Why do you say that the GEM is unsuited for deco diving?
What sort of provision do you have for OC bailout when diving the GEM?

The GEM connects to a normal regulator attached to a normal scuba tank like an 80cft. Instead of having two second stages one is replaced by the GEM and the other would be used as a bailout reg. First let me say about the deco part that the GEM gets used for deco diving, and you can find courses that teach you how to use the GEM for this. I have been a tec diver and believe in redundancy. The GEM has only one O2 sensor. If it fails you have to go to bailout, and when doing deco emergencies are never a good thing. These O2 cells just have a habit to stop functioning when you least expect it. This is why most of the ccr have 3 of them.

 

[mathauck0814]

... Or 5

 

[Sevenrider860]

Dirty-Dog,


Rob Neto (Dive-aholic) has used the GEM since 2011 and performs deep cave dives with the unit (280 feet). The ability to easily switch between gasses (travel, deep and deco) is what really makes this unit stand out and why I purchased one. I have heard that it was actually designed with technical diving in mind, but that is second hand information that I can not personally confirm.



Rob's experience with the unit is in the thread below.


http://www.scubaboard.com/forums/rebreather-diving/385758-my-experiences-rebreather-diving-2.html

 

[Dive-aholic]

The GEM connects to a normal regulator attached to a normal scuba tank like an 80cft. Instead of having two second stages one is replaced by the GEM and the other would be used as a bailout reg. First let me say about the deco part that the GEM gets used for deco diving, and you can find courses that teach you how to use the GEM for this. I have been a tec diver and believe in redundancy. The GEM has only one O2 sensor. If it fails you have to go to bailout, and when doing deco emergencies are never a good thing. These O2 cells just have a habit to stop functioning when you least expect it. This is why most of the ccr have 3 of them.

Actually, there are currently no courses that teach you how to use the GEM for decompression diving. They are in the works but the only approved courses so far are the GEM PSCR Level I and the Gem Sidekick Diver. I teach both. As Sevenrider860, the GEM was designed with technical diving in mind. Actually, it was designed with a 300' deep cave in mind. I've had my GEM to greater than 250' several times. That being said, I don't recommend anyone do this without the proper training and experience.

While it's true that the GEM has only one O2 sensor and if it fails you should bailout, this doesn't make it unsafe. I have yet to have the sensor on my GEM. The reason it only needs one O2 sensor is because there's no way to change the gas you're breathing. The design of the GEM makes it so the gas in the loop is about 4-5% lower than the gas in the supply cylinder. It's not like a CCR where you can inject more O2 or more diluent gas to change it. It is what it is. Can it be something different than 4-5% less? Yes, hence the sensor. But it's not very likely. Also, KISS does have plans to release a T piece that will accommodate 3 O2 sensors at some point in the future. Even in a CCR, if one of the sensors fail, you're supposed to bailout. There is no way to know whether the 2 sensors or the 1 sensor is correct. And you don't want to rely only on 2 sensors to control your set point. So regardless, if an O2 sensor fails, no matter how many you have, you bailout.

Finally, you can dive the GEM with a completely different bailout tank. That is usually how I dive mine. My supply gas and my bailout gas are 2 different sources. But most of my GEM dives are decompression dives and I don't want to count on just one tank for those dives.

 

[scubaab]

Thanks Dive-aholic for giving me some more info. As I said in the beginning it is just my opinion. Everybody has a different level of what they find acceptable risk. As an open circuit tec diver I have done many extended dives that others might have found as an unacceptable risk. As I get more experience and understanding my opinion could change.