Choosing my first rebreather SF2 vs JJ

[Henry_LKW]

Hi all! I'm here looking for advice on which rebreather to get! Living in Singapore, there is not much CCR diver presence and the one of the only means to get certified would be to cross the border to Malaysia (about 4 hrs) to get any form of technical diving training. The dive shop I'm approaching (and where I did my Padi Tec 50) offer to sell a lightly used SF2 (but manufactured many years back) inclusive of the course at about 5500 USD. During my try ccr with the unit (my first experience in a ccr), I find the unit really hard to breathe to the point where my chest felt like it was burning and buoyancy all over the place. However, articles online informed me that its normal and will be better after getting more experience.

However, I also have been reading online where there are multiple users recommending the JJ CCR over the SF2 due to the easier WOB and reliability which the dive shop teaches on as well!

Would like to seek some opinions if I should spend the money on a new JJ CCR or go for the used SF2 use the money I saved for CCR consumables and future courses down the line?

My end goal for diving with a CCR would be for deep wrecks and cave diving!​

 

[DiveLikeAMuppet]

What really helps with a CCR is having a local group of divers who dive similar units and can help you, and more importantly - dive with you. It’s not OC, you need to dive the unit, at least one weekend per month and get some mentoring.

You also need reasonably local support for the unit as you cannot service everything yourself. I would base your decisions on these two factors.

So if you are doing OC Tec dives, I would look at the groups and boats where you dive to see what’s popular and ask around. If you only did PADI50 training and never dived much tec, it might help you if you build some of the support network first?

JJ is brilliant but it’s a full size unit. The best way to think about flying is to imagine that you are organising transport of a CCR instead of having an extra suitcase. So if you need to fly to dive, you might need to look at smaller units that compromise on other things.

Can’t speak for SF2. Depends on what you mean by many years ago?

CCR shouldn’t be difficult to breathe, not on a try-dive?

 

[Henry_LKW]

What really helps with a CCR is having a local group of divers who dive similar units and can help you, and more importantly - dive with you. It’s not OC, you need to dive the unit, at least one weekend per month and get some mentoring.

You also need reasonably local support for the unit as you cannot service everything yourself. I would base your decisions on these two factors.

So if you are doing OC Tec dives, I would look at the groups and boats where you dive to see what’s popular and ask around. If you only did PADI50 training and never dived much tec, it might help you if you build some of the support network first?

JJ is brilliant but it’s a full size unit. The best way to think about flying is to imagine that you are organising transport of a CCR instead of having an extra suitcase. So if you need to fly to dive, you might need to look at smaller units that compromise on other things.

Can’t speak for SF2. Depends on what you mean by many years ago?

CCR shouldn’t be difficult to breathe, not on a try-dive?

Thanks for providing some factors for considerations! Will weigh my options with these!

The SF2 was manufactured in 2018! and have only been used for 20 over hours or so!

My experience during try ccr was that I was attempting to keep loop at min volume and ever since then, every inhalation felt hard with a "heart burn" sensation. I was using my instructor's personal unit during the try ccr session.

 

[Heat Miser]

Have you been to see Jimmy Choo at Red Scuba Singapore about the Choptima.

I saw him on a Chop scootering past me at the Drop Off a couple of months ago when I was in Tulamben, Bali.

 

[DiveLikeAMuppet]

Thanks for providing some factors for considerations! Will weigh my options with these!

The SF2 was manufactured in 2018! and have only been used for 20 over hours or so!

You need to ask about prior service. With a JJ you send the head to the manufacturer every 5 years, and replace all the rubber bits, hoses and counterlungs every 10 years (as a maximum, should be done sooner) as these materials degrade with age. That’s on top of changing all o-rings etc every 1-2 years and servicing first stages. Cells need changing every 12 months.

So 20 hours is very low but the unit is potentially in poor shape if it hasn’t been used recently. Someone might be trying to dump their unit on you .

My experience during try ccr was that I was attempting to keep loop at min volume and ever since then, every inhalation felt hard with a "heart burn" sensation. I was using my instructor's personal unit during the try ccr session.

Maybe that’s SF2 thing? With a JJ you hit ADV that will add gas.

 

[Alex Ouroboros]

JJ..

 

[Dsix36]

I have heard several complaints about SF2s (especially the older ones) but the only bad thing I have heard about the JJ is that they are heavy if you want to travel with them. I did a very in depth introduction followed by a try dive on the SF2 but found the WOB to be extremely dependent upon trim on the water and head up on the surface was down right miserable very quickly.

 

[Henry_LKW]

Have you been to see Jimmy Choo at Red Scuba Singapore about the Choptima.

I saw him on a Chop scootering past me at the Drop Off a couple of months ago when I was in Tulamben, Bali.

I have talked to Jimmy and know that he is one of the good instructor in Singapore to look for in regards tech and Choptima. However why I choose not to pursue the Choptima would be (1) understand that BM CCR is the better config for new ccr divers and (2) he charges Choptima unit the same price as a new JJ (not sure if it’s the mark up price or the delivery charges from US)

 

[Henry_LKW]

So 20 hours is very low but the unit is potentially in poor shape if it hasn’t been used recently. Someone might be trying to dump their unit on you .


Maybe that’s SF2 thing? With a JJ you hit ADV that will add gas.

I do feel the ADV fired but perhaps I’m just not used to putting the effort to inhale and exhale from a CCR

I do appreciate that the SF2 is light weight but with my slightly bad experience (Hopefully it’s a user problem not a unit problem) from the try dive it, I’m considering the JJ!

 

[Henry_LKW]

I have heard several complaints about SF2s (especially the older ones) but the only bad thing I have heard about the JJ is that they are heavy if you want to travel with them.

Hmm how bad would JJ be for air travel? I understand it’s almost 20kg without the tanks and sorbs

I did a very in depth introduction followed by a try dive on the SF2 but found the WOB to be extremely dependent upon trim on the water and head up on the surface was down right miserable very quickly.

I understand u must be slightly off trim to have a good/ decent WOB?