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Brad, the 4.3l was from the website. If you read it in German it is quoted.
www.tecgroup.eu > SF2 ECCR
www.tecgroup.eu > SF2 ECCR
Scuba Force's Sf2 Rebreather... With Training By Tom Mccarthy
- Thread starter The Chairman
- Start date
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The sidemount unit, in trim like the photo, breaths better than anything i've ever been on. Why? Because almost everything is at lung level. It's not back or front mounted counterlungs, it's side mounted. Now that said sidemount units (excluding some of the earlier home build units which still had front mounter lungs) never breath that great when you're totally straight up and down. That said i've done a decent amount of cave diving with vertical restrictions and i've never felt overly uncomfortable. My time spent in that position is negligible. They're really not for everybody though and i'd especially never put a newbie CCR diver on one.
-Tom McCarthy
StoneRust.com | EastCoastWreckDiving.com
cool_hardware52
Contributor
I too have been "playing" with an SF2, although sadly not under water. A local PSD team purchased some and brought them to me to solve some "ease of use" issues.
I figured some of this threads participants might be interested. If there is a better place for this info feel free to move it.
The first request was for shorter back plate bolts. DSS back plates are quite flat and have fairly shallow center channels, not a bad thing with back mounted counter lungs, but the OEM bolts on the SF2 are very long. I machined up replacements that are no longer than necessary to secure a back plate and wing. These are fitted with DSS Delrin Thumwheels in 8 mm x 1.25
And with the thumbwheel
I figured some of this threads participants might be interested. If there is a better place for this info feel free to move it.
The first request was for shorter back plate bolts. DSS back plates are quite flat and have fairly shallow center channels, not a bad thing with back mounted counter lungs, but the OEM bolts on the SF2 are very long. I machined up replacements that are no longer than necessary to secure a back plate and wing. These are fitted with DSS Delrin Thumwheels in 8 mm x 1.25
And with the thumbwheel
cool_hardware52
Contributor
Next was difficulty inserting a filled scrubber into the upper tube and getting it to locate on the counterlung / ADV assembly. Adding some Taper to the three locators makes it far easier to load the scrubber when the upper carbon fiber tube is in place.
cool_hardware52
Contributor
Next was a handle. Apparently earlier SF2's were furnished with a wire "drawer pull" type handle that attached to the plate on the top of the head, but these have been discontinued.
The DSS handle (Version 3.0) is waterjet cut from 11 gauge stainless and formed to fit the SF2 center "spine". The actual handle portion is 7/8" delrin. The single 8mm bolt is trimmed to exact length so no sharp ends project beyond the stainless Nylok nut. The two small white "dots" on the divers side, one above and one below the 8 mm bolt are nylon set screws that take any "rock" out of the handle. Secure, enough clearance for a gloved hand, and a large enough diameter to comfortable lift the fully assembled RB. The handle does not interfere with the loop, and allows the head to be removed.
The DSS handle (Version 3.0) is waterjet cut from 11 gauge stainless and formed to fit the SF2 center "spine". The actual handle portion is 7/8" delrin. The single 8mm bolt is trimmed to exact length so no sharp ends project beyond the stainless Nylok nut. The two small white "dots" on the divers side, one above and one below the 8 mm bolt are nylon set screws that take any "rock" out of the handle. Secure, enough clearance for a gloved hand, and a large enough diameter to comfortable lift the fully assembled RB. The handle does not interfere with the loop, and allows the head to be removed.
cool_hardware52
Contributor
The entire machine is very nicely made, but the PSD team members found it challenging to retrieve the removable scrubber screen from the scrubber, particularly if the scrubber was only partially filled. The OEM screen lacks any way to grab it. In addition the screen and spring and retainer assembly consists of 6 individual parts.
Keeping track of these small parts on a deck of a dive boats could be problematic.
Our solution was to make all 6 pieces into a single unit, with a captive DSS delring 8mm x 1.25 thumbwheel topping off the stack. A small piece of delrin is fastened to the screen and a new spring retainer cap with the captive thumbwheel replaces the Oem retainer. Two small Stainless screw in the sides of the delrin retainer and delrin spring base prevent keep the spring from slipping off. In use the spring forces hold everything together, when changing sorb there is now a single part to keep track of, and the screen is easy to remove even if it is 1/2 down the inside of the scrubber.
This modification does require accurately locating and drilling two 1/8" holes in the screen assembly to allow attachment of the delrin spring base to the screen.
Tobin
Our solution was to make all 6 pieces into a single unit, with a captive DSS delring 8mm x 1.25 thumbwheel topping off the stack. A small piece of delrin is fastened to the screen and a new spring retainer cap with the captive thumbwheel replaces the Oem retainer. Two small Stainless screw in the sides of the delrin retainer and delrin spring base prevent keep the spring from slipping off. In use the spring forces hold everything together, when changing sorb there is now a single part to keep track of, and the screen is easy to remove even if it is 1/2 down the inside of the scrubber.
This modification does require accurately locating and drilling two 1/8" holes in the screen assembly to allow attachment of the delrin spring base to the screen.
Tobin
OP
OW teaching is eating into my rebreather time. I've only got 4 dives and just a few minutes less than 3 hours on my SF2 this past week. I've had it twice on Speigel Grove though and that's been fun. My first boat dives, I felt very awkward donning and doffing my unit on the boat. I'm used to the positioning height on the back of my Sprinter and the boat allows it to sit way low. I really have to slouch to get my shoulders low enough for it. I'm going to make a stand for it. One that will allow me to build it without cylinders and it not fall over and that will also allow me to take it on the boat and give it some height when I suit up. I also want it to not open the automatic dump by contact as well as to vent it out. My mind is turning on this and I'm open to suggestions.
I've also developed a mini-routine to check that everything's turned on while I'm diving. I do this and a current limiting check on descent at 20ft and then any time I feel a need to. The last one is at the beginning of my ascent. This is in addition to the many, many times I glance at my PPO2 situation during the dive. It goes like this:
✔PPO2=>✔SPGs=>DIL&O2 Valves Off=>Back On=>Isolators Off=>Back On=>✔PPO2
FWIW, the last time on the boat was far better. I found a lip to sit the unit on while I kitted up and that made all the difference. I have to say that Rainbow Reef is awesome when it comes to accommodating rebreather divers. I think they have more rebreather divers off of their boats than just about anyone else in the Keys at this point. They are quick to help you with the little things like your bail out bottle and you can get your tanks easily filled on site. They are also patient with you when you need it. You dive at your pace, not theirs and I really appreciate that. They rock! A big shout out to Captain Cici and her crew!
I've also developed a mini-routine to check that everything's turned on while I'm diving. I do this and a current limiting check on descent at 20ft and then any time I feel a need to. The last one is at the beginning of my ascent. This is in addition to the many, many times I glance at my PPO2 situation during the dive. It goes like this:
✔PPO2=>✔SPGs=>DIL&O2 Valves Off=>Back On=>Isolators Off=>Back On=>✔PPO2
FWIW, the last time on the boat was far better. I found a lip to sit the unit on while I kitted up and that made all the difference. I have to say that Rainbow Reef is awesome when it comes to accommodating rebreather divers. I think they have more rebreather divers off of their boats than just about anyone else in the Keys at this point. They are quick to help you with the little things like your bail out bottle and you can get your tanks easily filled on site. They are also patient with you when you need it. You dive at your pace, not theirs and I really appreciate that. They rock! A big shout out to Captain Cici and her crew!
teknitroxdiver
Contributor
OP
I have no idea. I don't think I would try.
The problem with carry on is the latches that hold the head on are attached to the bottom section, so the overall lenght can't be changed by much more than removing the head, which is about 3" (not including the sidemount handle on top).I've heard you can bend the latch bands a little to get another inch or so, but it's still long for a carry on.
Maybe with a soft cover like some of the revo people do it, and just wear it like a backpack?
-Chris
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