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Thread: SF2 versus JJ. Thoughts please?

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    RBW Member damianb is an unknown quantity at this point damianb's Avatar
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    SF2 versus JJ. Thoughts please?

    Hi guys. I posted this on another site but keen to hear if you guys also have thoughts on the following...

    I am pretty new to CCR having just done my JJ - TDI air dil deco diver course last month. I don't have a unit yet. I dived a JJ again this weekend Saturday and Sunday and I really love it, It just feels so comfortable and balanced. I know someone who is selling a unit and I'm slowly but surely talking myself into buying it. However, I recently heard some good stuff on the SF2. I saw one this weekend an they look solid.

    Can those in the know, offer pro's and cons for JJ versus SF2. I am not considering any other units right now, so can we please stay on point with thoughts on these two units :)

  2. #2
    RBW Member kaj crucq is an unknown quantity at this point kaj crucq's Avatar
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    Re: SF2 versus JJ. Thoughts please?

    Hey Damian.


    I dived both units too before i did my MOD1.


    The SF2 is solid as a rock. no doubt about that. the carbon fibre canister is light and strong. Maintenance is easy. but my experience with breathing on the SF2 wasn't that good. in perfect horizontal position it breaths ok. but as soon you get a little bit head up position you'll get hamster cheeks. just a little bit head down feels like sucking a thick milkshake. I think it's because the counterlung is way to far from the lungs with a big static pressure difference as result.


    the breathing loop i didn't like. it has way to much positive buoyancy. however it seems that there are counter weights available.


    I finally went for the JJ. it breaths way easier then the sf2 in my opinion. maintenance is a bit more work on the JJ.


    just make a try dive on the SF2 if possible, and feel the difference.
    I'm just about to finish my MOD1 and have my own JJ allready. I love the Unit, unless I don't have that much rebreather experience yet.


    greetz kaj
    Last edited by kaj crucq; 4th November 2015 at 11:46.

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    RBW Member dspe is an unknown quantity at this point dspe's Avatar
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    Re: SF2 versus JJ. Thoughts please?

    BUY THE JJ you wont regret it.

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    Re: SF2 versus JJ. Thoughts please?

    The SF2, as a SM rebreather is more of a specialist rebreather; in that it is made to combat tight penetrations that would prove inaccessible with the standard bm rb.

    I was stuck trying to make the same decision as you were several months ago and my instructor helped educate me to make the wisest choice possible for the type of diving I am currently restricted to.

    Unless you plan on diving tight caves/wrecks in the immediate future, there is no point sacrificing your wob when you dont need to.

    As a result, I ended up purchasing a bm rb (isc meg), however as my diving goal is to dive caves, I will be making the switch to sm rb in the next few years once I earn the relevant certifications and a bm rb is no longer 'fit for pupose'.

    Sidemount, Backmount, No Mount are all tools for a job. Its easier to use the right tools for the job and limit potential failure or worse.

    Either way, enjoy the benefits of CCRs!!!!!

    Cheers mate

    Mike

    Sent from my SM-G920I using Tapatalk

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    Re: SF2 versus JJ. Thoughts please?

    Quote Originally Posted by Deerey  View Original Post
    Unless you plan on diving tight caves/wrecks in the immediate future, there is no point sacrificing your wob when you dont need to.

    Sidemount, Backmount, No Mount are all tools for a job. Its easier to use the right tools for the job and limit potential failure or worse.
    Sure :) makes no sense to go SM just to go SM, obviously there needs to be a purpose for this.. In regards to BOB it also always makes sense to look at options, like starnawski did with his dual hammerhead i.e. backmount two..
    As far as it comes to myself.. I had been BM diving Rebreathers a lot. For the last years I had been more concentrating on OC SM caving hence the interest in a SM breather essentially use it to further my OC SM cave diving..

  6. #6
    RBW Member damianb is an unknown quantity at this point damianb's Avatar
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    Re: SF2 versus JJ. Thoughts please?

    Thanks for this Kaj :)
    I've mad my mind up.
    Quote Originally Posted by kaj crucq  View Original Post
    Hey Damian.


    I dived both units too before i did my MOD1.


    The SF2 is solid as a rock. no doubt about that. the carbon fibre canister is light and strong. Maintenance is easy. but my experience with breathing on the SF2 wasn't that good. in perfect horizontal position it breaths ok. but as soon you get a little bit head up position you'll get hamster cheeks. just a little bit head down feels like sucking a thick milkshake. I think it's because the counterlung is way to far from the lungs with a big static pressure difference as result.


    the breathing loop i didn't like. it has way to much positive buoyancy. however it seems that there are counter weights available.


    I finally went for the JJ. it breaths way easier then the sf2 in my opinion. maintenance is a bit more work on the JJ.


    just make a try dive on the SF2 if possible, and feel the difference.
    I'm just about to finish my MOD1 and have my own JJ allready. I love the Unit, unless I don't have that much rebreather experience yet.


    greetz kaj

  7. #7
    RBW Member damianb is an unknown quantity at this point damianb's Avatar
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    Re: SF2 versus JJ. Thoughts please?

    Logical thinking. Cheers.
    I've made up my mind and it starts with a J and ends with a J.
    Quote Originally Posted by Deerey  View Original Post
    The SF2, as a SM rebreather is more of a specialist rebreather; in that it is made to combat tight penetrations that would prove inaccessible with the standard bm rb.

    I was stuck trying to make the same decision as you were several months ago and my instructor helped educate me to make the wisest choice possible for the type of diving I am currently restricted to.

    Unless you plan on diving tight caves/wrecks in the immediate future, there is no point sacrificing your wob when you dont need to.

    As a result, I ended up purchasing a bm rb (isc meg), however as my diving goal is to dive caves, I will be making the switch to sm rb in the next few years once I earn the relevant certifications and a bm rb is no longer 'fit for pupose'.

    Sidemount, Backmount, No Mount are all tools for a job. Its easier to use the right tools for the job and limit potential failure or worse.

    Either way, enjoy the benefits of CCRs!!!!!

    Cheers mate

    Mike

    Sent from my SM-G920I using Tapatalk

  8. #8
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    Re: SF2 versus JJ. Thoughts please?


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    Re: SF2 versus JJ. Thoughts please?

    I'm pretty biased now because I'm an instructor on the SF2 and have a lot to gain financially by liking it. That said, there was a point that I didn't and I ended up buying one. I'll just touch on what I liked when I was looking and not bash anything. I found that it breathed great in every position in backmount. Obviously in sidemount it's a lot more position dependent just because of where the counter lung is. I find it's an acceptable trade off as opposed to having unprotected/crushable front mounted lungs in tight sidemount situations. It's also nice being able to blow water out the base of the counterlung by over pressurizing the loop with dil. Ted Mccoy and James Draker (James is the US contact for scubaforce now) have been doing huge exploration cave dives sub 300' on the unit and haven't had any complaints. Just my two cents. Good luck with your choice, they're both solid units.
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