So now I'm an SF2 instructor...

[kensuf]

Then how do you walk down the cave passages?

You know, part of me is laughing because yesterday afternoon I told a well known cave instructor a story about how I had to bunny hop on my feet in a cave once while carrying a boulder in my hands to get just the perfect line anchor for the gold line that's in the first 100' of Little River. Basically I would squat while holding the boulder, then jump to move a foot at a time forward.

 

[kensuf]

Sometimes it's not possible in a cave...and if I'm diving a sidemount CCR it's so I can get in a cave. Of course there are ways to mitigate that, and there aren't really better options out there yet, but it's not as easy as just "stay flat all the time" for some folks.

My main concern with it is the counterlung size. I have a 7.5ish Liter lung capacity, and my understanding is the SF2 is optimistically rated at 4.2L

Simple solution on the lung volume - try dive and see for yourself!

As for the sidemount stuff, I know two guys that pushed SF2's through a no-mount restriction in 290' of water about 2500' back in a cave to do some exploration. The "glory hole" was in the ceiling of the tunnel they were coming from, and in the floor of the room they found on the other side. They had no choice but to go vertical to get in and out of the new passage, but they managed to do it.

Personally, I'm not into no-mount restrictions in 290' of water...

 

[victorzamora]

Simple solution on the lung volume - try dive and see for yourself!

It's on my very-short-list of units to try before putting any real money down on anything. The meager lung volume is one major fear I have with it, but not enough to keep me from trying it.

As for the sidemount stuff, I know two guys that pushed SF2's through a no-mount restriction in 290' of water about 2500' back in a cave to do some exploration. The "glory hole" was in the ceiling of the tunnel they were coming from, and in the floor of the room they found on the other side. They had no choice but to go vertical to get in and out of the new passage, but they managed to do it.

Personally, I'm not into no-mount restrictions in 290' of water...

My comment about sidemounting in a cave isn't that the SF2 isn't capable of being dove SM in a cave....it's that if I'm giving up the ease and convenience of BMCCR for the hassle of SMCCR, you can bet your butt it won't spend its life at 30ft in the Keys in OW. Don't get me wrong, I'd have no issue taking it on reef dives and don't fault those that do....I'm just saying that "stay flat" isn't always an option where a SMCCR is meant to be: in a cave.

You know, part of me is laughing because yesterday afternoon I told a well known cave instructor a story about how I had to bunny hop on my feet in a cave once while carrying a boulder in my hands to get just the perfect line anchor for the gold line that's in the first 100' of Little River. Basically I would squat while holding the boulder, then jump to move a foot at a time forward.

I would've paid GOOD money to watch that!

 

[The Chairman]

Damn, Ken! That's phreakin awesome! We'll have to dive our SF2s together!

 

[kensuf]

I would've paid GOOD money to watch that!

Next time you're in LR, look at the two boulders in the middle of the tunnel right before the chimney. Those weren't there originally...

 

[JohnnyC]

Sometimes it's not possible in a cave...and if I'm diving a sidemount CCR it's so I can get in a cave. Of course there are ways to mitigate that, and there aren't really better options out there yet, but it's not as easy as just "stay flat all the time" for some folks.

My main concern with it is the counterlung size. I have a 7.5ish Liter lung capacity, and my understanding is the SF2 is optimistically rated at 4.2L

Sure, but if you're taking off your rebreather, sidemount or otherwise to navigate a restriction, they're all going to breathe equally as bad. Ever take a Meg off underwater? Good luck trying to reasonably do anything with it. The SF2 excels in that since the counterlungs are self-contained, you can more easily navigate with the unit regardless of configuration.

As for not maintaining trim, sure, there are situations where that arises, and they're momentary. It's not like you're going to be breathing off a bag that's a meter above your head for half an hour fighting hydrostatic imbalance. And if that's the case, you're much better off bringing an extra stage of whatever gas you need and doing it OC, regardless of rebreather design, because they will all suck. And if it's low, you can throw it in front of you just like a sidemount bottle and maintain depth so there's no imbalance at all. Can't do that well with a unit with OTSCL's. Even my Pelagian with BMCL's is annoying when it's off.

At the end of the day, it's just people trying to make a mountain out of a molehill. Everyone I've spoken to says it breathes great in trim, and while you can tell a difference when the CL is either above or below your lungs, it's not horrible at all.

As for lung capacity, you should be running minimum loop volume. You're not entirely filling your lungs with every breath so your max lung volume means very little. If you've never tried a rebreather before, you need to relearn how to breathe. It's definitely different, and it takes getting used to.

 

[jerrwhy01]

Great, there will be no living with Ken now.

 

[kensuf]

Great, there will be no living with Ken now.

Lol! Jerry, just for you, I will let my head swell a bit.

 

[Kristi@CCDS]

Congrats Ken, a certification well earned and well deserved. I know you will be a fantastic rebreather instructor.

 

[sea_ledford]

Thanks. I'm doing a demo on one hopefully soon. Now the hard question on a public forum..Is there anything you don't like about the SF2?

I assume that was aimed at Ken, but I'll answer as well.

Breathing at the surface (vertical, head out of the water) totally sucks. Switch to OC for that. I've only had to do it once waiting for a boat pickup, but staying on the loop wasn't really an option. Underwater vertical has been covered and I agree with everyone else in this regard... not great, but not impossible either.

My biggest issue so far has been the placement of the cells and collecting condensation. If I go vertical without knocking on the top of the unit, mine seems to collect the condensation on top of the #2 cell. It seems to drip off the top of the head and land right on that cell. This usually happens to me at the end of the dive when I'm getting back on the boat and I'm on 100% anyway, but getting a slow cell during a dive due to condensation has been an issue a couple times. I had to call one dive because I didn't open up the loop to let it dry out between dives and it wouldn't read correctly or calibrate. Because it had a big drop of water on the cell face.

I had 2 of my three original cells crap out on me within about six months, last one died at 9 months. Replacements have been rock solid so far.

Things I have changed:
-Swapped to Cooper hoses. When I ordered my unit they still came with the 15 foot long loop hoses. The current ones are an appropriate length.
-Added a Shrimp BOV
-Added an AV1 HUD. That thing kicks ass. About the size of your thumb and plugs straight into the fischer connector. no battery box, no additional cable. You can get them from Silent O Solutions.
-removed the inline shut off on the O2 side first stage.
- I didn't like that the dill MAV and the wing inflate hang on top of one another with the add buttons on the same side (added dil instead of adding air to wing more than once), so I swapped out for a shorter infiltrator hose (12" I think) and turned around the MAV. So MAV button in inboard, inflate button is outboard and higher on my shoulder.

Overall I really like the unit, but I'm still trying to determine if the condensation thing is a design issue or a "I don't know how to dive it" issue. I haven't heard anyone else complain about it.

-Chris