Question SCR Semi Closed Rebreather

[Dann-Oh]

Hey all I am looking for some basic information on SCR units. I am looking for extended bottom time within Recreational diving limits(my current depth limits are 130FSW and no decompression). I'm currently diving single back gas (AL62, LP72, HP100) and sidemount (I have a set of both LP72 and LP50 for side mount). I was talking with a tech in my LDS and he mentioned I may want to look into SCR units for extending my bottom time within Recreational limits. I do have desire to eventually get into tec for deeper wreck dives (one is the Infadel in 150FSW and a second is UB88 in 190 FSW), I do know I want to wait until my kid(s) is/are older.

I don't really have many friends that dive rebreather at the moment but I do know there is a local community but im not a part of them yet.

Thoughts on going with an SCR at this point in my dive career?

 

[Robert H. Diver]

Hey all I am looking for some basic information on SCR units. I am looking for extended bottom time within Recreational diving limits(my current depth limits are 130FSW and no decompression). I'm currently diving single back gas (AL62, LP72, HP100) and sidemount (I have a set of both LP72 and LP50 for side mount). I was talking with a tech in my LDS and he mentioned I may want to look into SCR units for extending my bottom time within Recreational limits. I do have desire to eventually get into tec for deeper wreck dives (one is the Infadel in 150FSW and a second is UB88 in 190 FSW), I do know I want to wait until my kid(s) is/are older.

I don't really have many friends that dive rebreather at the moment but I do know there is a local community but im not a part of them yet.

Thoughts on going with an SCR at this point in my dive career?

I am NO authority on rebreathers, there are people that will comment on this that have forgotten more about SCR/CCR than I’ll probably ever know…but IMO just do CCR…SCR is kinda pointless…especially if you want to do deep tec dives in the future.

 

[lermontov]

does your local LDS sell scr rebreathers?- why do you want to wait til the kids are older ? whats the criteria on going rebreather based on their age?

in regard to "at this point of my career"what does that mean ?

 

[Marie13]

I am NO authority on rebreathers, there are people that will comment on this that have forgotten more about SCR/CCR than I’ll probably ever know…but IMO just do CCR…SCR is kinda pointless…especially if you want to do deep tec dives in the future.

Yeah, SCR pretty worthless. Does anyone dive them now? You can get a rebreather and dive shallow. The first CCR cert with TDI is to 100ft. There’s one member here whose wife dives CCR and only within recreational depths.

 

[tbone1004]

Hey all I am looking for some basic information on SCR units. I am looking for extended bottom time within Recreational diving limits(my current depth limits are 130FSW and no decompression). I'm currently diving single back gas (AL62, LP72, HP100) and sidemount (I have a set of both LP72 and LP50 for side mount). I was talking with a tech in my LDS and he mentioned I may want to look into SCR units for extending my bottom time within Recreational limits. I do have desire to eventually get into tec for deeper wreck dives (one is the Infadel in 150FSW and a second is UB88 in 190 FSW), I do know I want to wait until my kid(s) is/are older.

I don't really have many friends that dive rebreather at the moment but I do know there is a local community but im not a part of them yet.

Thoughts on going with an SCR at this point in my dive career?

You don't say what your actual limitation is, Gas or NDL, nor do you say what your SAC rate is so it's hard to make blanket suggestions in most cases but this one is thankfully pretty easy.

On SCR you will still be bound by NDL and since the SCR lowers the ppO2 in the loop compared to breathing on OC you either have to compensate with a higher nitrox percentage or you will actually hit NDL faster than if you were on open circuit. All depends on where you are getting fills. That said though, if you are bound by NDL, the SCR isn't going to get you anywhere and you're still using pretty small backgas cylinders so I would go up to bigger bottles before I went with SCR if strictly as a gas extender for open water.

The Horizon is really the only SCR on the market and it is capped at 3hrs before you have to change the scrubber, it is also has a mfg max depth of 40m.
Technically KISS still makes the Gem but you really don't want that, and technically Halcyon still makes the RB-80 but you aren't getting anywhere near a RB-80 training without going through the full run of GUE courses and it is probably a 5-6year process at the shortest to get there.

SCR has some really powerful attributes that make it an incredibly tool for very specific applications and arguably better than a CCR. Long range cave diving in specific systems/as a bailout rebreather where you have pretty constant depths when used as a primary rebreather. By not having to deal with sensors or onboard oxygen you have a much more simple system that is only marginally less efficient than a CCR but without all of the hassle of the sensors. As a bailout rebreather it also removes the complexity of the sensors and maintenance tied to it while giving you huge gas extension for the exit, arguably only justified if you are well over a mile back in a trimix depth cave. Second is shallow water photography/videography where you want to be on a loop to be quiet and while a SCR isn't silent it's almost there but since it only has to contend with one of the 3 H's *only hypercapnia, no hyperoxia or hypoxia* and you don't have to babysit sensors it removes a lot of risks that are usually dealt with by safety divers. Other than those two super specific applications where there are only a handful of divers globally that can justify it, SCR's don't really have a place IMO, certainly not for recreational diving.

 

[OTF]

I think in your case there's a good argument to take AN/DP and dive big tanks of nitrox. Being able to add a few minutes of deco will extend your dives a lot, you don't have to be going beyond 130 for deco to be useful. You'll get more bang for your buck in terms of cost and effort than going to a rebreather, and if you dive rebreathers you'll end up wanting to do deco on them anyway.

Do you currently find that gas or NDL is your limiting factor on most dives?

As for SCRs, they seem to be out of fashion these days, I'm not sure I've ever actually seen someone dive one in person. But CCR seems to be gaining popularity.

 

[Centrals]

I have done SCR course 24yrs(Drager) ago so unless there is new development in knowledge, technology etc., NDL is still the limitation of the unit.
I have seen mantis shrimp and octopus came out from their hiding places without realizing I was there(on SCR). GREAT.

 

[lostsheep]

Yeah, SCR pretty worthless. Does anyone dive them now? You can get a rebreather and dive shallow. The first CCR cert with TDI is to 100ft. There’s one member here whose wife dives CCR and only within recreational depths.

You can go straight to Helitrox if you are already AN / DP.

Helium and rebreathers were made for one another

 

[grantctobin]

Yeah, SCR pretty worthless. Does anyone dive them now?

Again, you continue to talk about things that you know naught about

 

[Asheron]

I've got a kiss Gem and it's a fun little unit. I am also certified on the horizon, but am no where near enthusiastic about it. The horizon needs tons of lead and where it is positioned using pockets it makes it hard to clip the sidemount cylinders. Also all the "safety" systems are very annoying and make the unit sometimes uncomfortable.

The Gem I found to be a better unit even as awkward as it looks attached to an aluminum 80.

If I had to pay full price for a current SCR I would just buy a chest mount CCR. If you are looking for a serious SCR then get a used Tres President's, but there really is no benefit to getting such a beastly unit if it doesn't match you needs.