SF2 ccr

Warning. Everything that you read here about the rebreather is my personal opinion!
General infoThe rebreather is produced by Scubaforce company, in Germany. The rebreather can be in backmount and sidemount configuration. For the same body, there is a conversion kit for both of the configurations. In this review, I write only about sidemount configuration, because I believe that only sidemount configuration is good for cave diving. You can dive with backmount only if the logistics till the water are simple, there is no necessity to pass dry rooms in the cave. SF2 is a simple and reliable rebreather. The counterlungs are placed on the bottom of the rebreather. If you use the backmount configuration, it doesn’t make a problem, but in sidemount configuration, the distance between your lungs and counterlungs is too big and when you are in a vertical position, you feel you are a "frog". The tension in your cheeks is so strong, that you release the gas from your close circle to the water not to be able to prevent losing it. The closer you are to the surface, the bigger the problem. Divers normally change CC to OC, pass the vertical passage in OC, and after switch back to CC. This specific of the rebreather makes it not so popular in use nowadays, but there are a lot of fans of the rebreather who like the simplicity and reliability of the machine. The material of the body of the rebreather is carbon and the head on the top is from delrin. In this review, I publish photos of a predecessor of SF2. I am a user of this machine. My rebreather has the same construction and everything is the same just looks a bit different, but no electronics. It is possible to convert it to mCCR that is why you see the fisher connector on the head, but I do not need it. For some rough conditions with zero visibility, it is always good to have an instrument the same reliable as an open circuit.I am a dealer of Scubaforce in Portugal, but not an instructor. Despite my reb is not 100% SF2, the behavior of the rebreather underwater is the same that is why I call my rebreather a passive semi-closed SF2. You can come, try the machine and compare it with the other sidemount rebreathers which I have.

The sizeThe diameter and height of the rebreather are very similar with s80. It is very comfortable to use, especially in no-mount position.

The breathing hoses and connectorsThe connectors of the rebreather have an original construction. There are rotating rings with a thread between the breathing hoses and the head. There are no quick connectors on the Scubaforce DSV, due to checking the condition of the mushrooms, washing and drying procedures can be done only with the assembled breathing loop. You can buy the rebreather with IQsub DSV and have their quick connectors on the hoses. It is more practical. 

DSVSidemount SF2 supplies with IQsub DSV nowadays. The DSV has a handle to switch your breath to the closed circuit. The handle goes as a clock in parallel with your face. 

The counterlungsThe counterlungs are placed in the bottom of the rebreather. They look like harmony. The position of the counterlungs in sidemount configuration, as I mentioned above, makes some difficulties with normal breathing for you on a shallow depth in vertical passages, but you can compensate for the technical nuance with the tactic of using the rebreather. Change CC to OC to pass the passage and switch to CC back. In the down part of the “harmony”, there is an Apeks releasing valve. Rotating the valve you can adjust the lightness of breathing, but anyway, you can have some difficulties and the breathing tension can be too high even with the almost open valve. Be aware that the more open the position of the valve the more gas you lose from the circuit.

Mccr and eCCRSF2 is eCCR rebreather. I have not heard that someone made mCCR from SF2, but it is possible to do so with no problem. 

The head and electronicsSF2 uses the electronics of Shearwater. A controller and ppO2 monitor can be connected through Fisher connectors. You can connect Scubaforce Fisher HUD as well. On the photo from the manual of SF2, you can see the construction of the eCCR´s head.

SF2 CCR, the head

The canister and scrubberThe scrubber is placed on the top of the rebreather, just after the head. The scrubber is axial. The capacity is 2.2 kg. There is no canister, but a body where the scrubber is. It is from carbon.

Gas connectionThere is no on-board gas from the manufacturer, but you can place a bracket to the body of the counterlungs by yourself. There is a space for one 2L carbon bottle, but I have not seen that someone does like this. Normally the divers, and me too, connect only off-board gas. It is possible to add quick connectors. QC4 or 6 as an example.

ADVThe ADV works well. The “harmony” counterlungs go up and down with every breath. When the bottom of the “harmony” reaches the spring of Apeks like the second stage, it injects the portion of the Diluent. It is very easy and works well. On the bottom of the “harmony”, there is an Apeks releasing valve. It needs to adjust the tension of the breath. On the left photo from the manual of SF2, you can see the construction of the ADV.

TransportationThe rebreather is lightweight. You can put the assembled SF2 in a suitcase with medium size and fly.

WashingSF2 is very simple and easy to wash. It takes time to dry a “harmony” counterlungs.