SF2 vs JJ vs Liberty

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Evan Davies

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Hey guys,

So, i'm looking at buying my own RB. Certified on the SF2 up to Helitrox Deco. Got plenty of instructors around.

Might want to switch to SM CCR later, where the SF2 and Liberty would be better as they have sidemount version. As far as I know the JJ does not have any option for this.

I like the simplicity of the SF2 in a technical sense, where it all is inside one tube. Same goes for the SF2 SM and the Liberty SM.

Pros & Cons about them in your opinions?

Thanks guys
 

tbone1004

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SF2 important points- uses funky cells, axial scrubber, SM unit isn't self contained with bottles, but unit as a whole is. Pros and cons to the lung being in the tube as far as work of breathing is concerned
JJ-doesn't have sidemount capability without crazy DIY solutions, not "self contained" like the SF2
Liberty-doesn't use Shearwater electronics, big and heavy, not self contained like the SF2

What drew you to the SF2 in the first place? What has you looking at the other units? What do you think the pros and cons are?
 
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Evan Davies

Evan Davies

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SF2 important points- uses funky cells, axial scrubber, SM unit isn't self contained with bottles, but unit as a whole is. Pros and cons to the lung being in the tube as far as work of breathing is concerned
JJ-doesn't have sidemount capability without crazy DIY solutions, not "self contained" like the SF2
Liberty-doesn't use Shearwater electronics, big and heavy, not self contained like the SF2

What drew you to the SF2 in the first place? What has you looking at the other units? What do you think the pros and cons are?

What drew me to the SF2 is that my ANDP instructor is an instructor for the SF2. The WoB I actually didn't have much problem with, though I am aware of that it seems to be an issue for others due to the location of the CL.
Doesn't the JJ use an axial scrubber too?
 

rddvet

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I originally considered an SF2 until I was around them more and felt they were just big and cumbersome. The head seems to stick up higher than most units. Either way I'm glad of my choice. SF2s were hot here for a little while because they were being pushed by a couple of instructors. The used units are flooding the market as people move away from them to different units. There are also quite a few reported issues with cracked heads. Not surprisingly since carbon fiber's a poor material choice.
Of the 3 you've mentioned, I personally would go with the JJ. It's robust and hard to kill.
 

helodriver87

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Can only speak to the JJ right now, but I love it. It's big, especially if you're running onboard dil/BO, but it's very durable and, in my limited experience, reliable. I like the design philosophy and I see myself sticking with it for quite awhile. I don't like the way debris gets trapped around the head o rings, but it's been fine so far. I also don't love the positioning of the counterlung OPV. Makes flood recovery awkward in limited space situations. Other than that, it's a great unit. If I were to go SMCCR, I'd just get a dedicated unit. From what I know about the drawbacks of the various options out there, I'd rather dive the JJ unless I needed the SM form factor.
 

tbone1004

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What drew me to the SF2 is that my ANDP instructor is an instructor for the SF2. The WoB I actually didn't have much problem with, though I am aware of that it seems to be an issue for others due to the location of the CL.
Doesn't the JJ use an axial scrubber too?

JJ has the option to use radial though. Pros and cons, but it's a variable.
 

rddvet

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Can only speak to the JJ right now, but I love it. It's big, especially if you're running onboard dil/BO, but it's very durable and, in my limited experience, reliable. I like the design philosophy and I see myself sticking with it for quite awhile. I don't like the way debris gets trapped around the head o rings, but it's been fine so far. I also don't love the positioning of the counterlung OPV. Makes flood recovery awkward in limited space situations. Other than that, it's a great unit. If I were to go SMCCR, I'd just get a dedicated unit. From what I know about the drawbacks of the various options out there, I'd rather dive the JJ unless I needed the SM form factor.

Agree with the sm sentiment. All sm rebreathers come with really serious cons. The main one being bailout being limited to one main and one stage as opposed to a set of sm mains for a bm unit.
 

Madddogggy

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The standard JJ comes with a 5.5lb (2.5kg) axial scrubber from JJ. The radial scrubber (slightly larger) is an option, which may need to be purchased in addition to the axial. Some of the JJ add-ons are only available after a diver is certified on the unit.

If you don't mind the heavy weight, the JJ, as mentioned by others is built like a tank.
 

Big-swede

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Hi.
I have never dived anyone of the units but the sf2 is made out of carbon fiber and that is a big no in my eyes.

Sure it's tough as ***** but when you drop it to hard or squeeze to tight in a cave the carbon fibre will crack and leak where delrin and aluminium will get a dent that probably wont harm the dive.
 

rjack321

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What drew me to the SF2 is that my ANDP instructor is an instructor for the SF2. The WoB I actually didn't have much problem with, though I am aware of that it seems to be an issue for others due to the location of the CL.
Doesn't the JJ use an axial scrubber too?
If you want crossover to a new unit I don't see any reason not to buy one but
Why not just stick with the SF2? What don't you like about it?
 
https://www.shearwater.com/products/peregrine/

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