SF2 rebreather

[giorgino]

Any info about the SF2 reb? It seems very interesting,because it is very simple, have the single counterlung coaxial with the can scrubber, no obstructions on the chest, also CE approved for Europe (where I live). In this board there are some info about demo days, but I like to have some fedback from divers that uset it because I'm considering tu buy a reb (first one for me).
Mny Thanks
Giorgino

 

[kensuf]

I spent two days on one and a good friend is an instructor on the unit, I also have a couple of friends diving them regularly.

The construction appears to be well made, the head is robust and well thought out, and the pendulum counterlung is really good at keeping everything dry. The CF works as an insulator, so the scrubber stays nice and warm and is more efficient than other materials. Personally, I like the counter lungs for helping to keep the unit clean. I'm not a fan of chest-mounted counterlungs.

My only complaint is that I'm not sure how durable the CF will be -- I raced bikes for 6 years and have seen too much broken carbon during that time. But I'm not ruling it out, and I'm keeping an eye on how the units hold up.

 

[giorgino]

Thnx Ken. my question was because apparently so few divers use SF2, but it is a very new unit. About the fiberglass CF, I just read others not good ideas, but I think don't affect to me because I do not plan to cave dive or sidemount it, because my dives are in Mediterranean sea only, so I think bumps will be very rare. I am a trimix DIR diver (sorry, I read your DWW orientation ;-)) doing 50-60 dives a year, not so much but not sporadic...
Can you tell me about the WOB of the unit, please?

 

[kensuf]

The unit breathed fine when you're in horizontal trim. Head down was difficult (like sucking through a straw) and feet down it feels like you get a super-venturi assist on inhalation.

The only other CCR's I've been on are a KISS Classic and a LAR V, so my ability to compare to other units is limited.

 

[tbone1004]

so a bit of misinformation. CF is not an insulator, it is very much a conductor. Fiberglass is an insulator, kevlar, etc, but carbon fiber is a very very good conductor, of both heat and electricity... Apparently they are using CF because they actually needed to cool the unit off, not keep it warm as the bed temps were getting too warm.

 

[sea_ledford]

The fragility of the carbon fiber is a non-issue. I have seen a couple sidemonut units that have been trashed for several years. The cf is certainly not new looking, but structurally they are still good enough to use as a wheel chock. Don't try to compare it to a bike frame as the goals of the designs are on opposite ends of the spectrum.

With regard to WOB, there are the published numbers (only in German as far as I have seen, but easy enough to figure out). I'm pretty sure I saw them on the SF2 facebook page a month or two ago. What you are more likely asking about is static lung load, which is what varies with position. Any backmounted CCR will have SLL issues in certain positions. The SF2's sweet spot is just slightly foot down from horizontal, but not bad in any position. Straight vertical isn't very pleasant, but maintaining minimum loop volume helps a LOT with that.

If you are new to the CCR world, just be aware that "WOB" is commonly used as SLL, but in reality they are completely different. If someone says the WOB is great in one position, but crap in another, they actually aren't talking about WOB, but SLL.

-Chris

 

[giorgino]

Thanks a lot to all for answers.
It seems to be a very good unit, and it interest me because I have a very good instructor at hand and this year it seems a little group of SF2 users is forming this year where I dive (Tuscan Archipelagus), so it will become easy to build teams SF2 related. My hope is to do quickly the 1° Mod (air) as an eCCR, and then to switch to trimix, perhaps in mCCR mode, when well surpassed the "overconfidence" point.in the Learning curve. Our best trimix dives here are in the range 50-90 metres (mine up to 65 around in OC) but I think I'll remain on air as diluent in the 5-30 metres range for the first year to consolidate the big changes in buoyancy and others skills that are different from OC diving.
Chris, thanks a lot also for explain the difference between WOB and SLL, very useful as I know I must change my point of view from OC to CC, that's new for me.
Any other help is very appreciated.

 

[The Chairman]

I just picked mine up and will be training on it mid March. I tried one out last year and I like the way it breathes horizontal. I spend most of my dives in that position, so it's fine for me.