LiteHedded
Contributor
i would just check it in a pelican case. that's what i'm doing with my rb80 (seems similar size and length wise)
Scuba Force's Sf2 Rebreather... With Training By Tom Mccarthy
- Thread starter The Chairman
- Start date
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OP
The Chairman
Chairman of the Board
Some lessons learned while diving shallow. While many like rebreathers to extend their NDLs and gas management at depth, my favorite part about a rebreather is the lack of bubbles and how close I can get to the critters. Consequently, I've been doing a number of shallow dives and have arrived at a few conclusions along the way. The biggest of these is that the ADV (Automatic Diluent Valve) is not your friend above 20 ft. I dove with @sphyon in Jules Underwater Park and Lodge (Key Largo) and then again at The Blue Heron Bridge (Phil Foster Park). He's playing around with sidemount and I'm still building experience on my SF2. We were floating on surface at Jules talking about what we were looking for as well as discussing sphyon's trails, and I noticed that every few seconds I would hear a gas fart. I checked my SPGs and discovered that I had lost a lot of gas. I told him we would meet on the bottom and descended. Due to equalization issues the man never made it down. 
No matter, I came back up but before I did, I slid the ADV isolator closed. We discussed his equalization issues and called the dive. In the meantime, I noticed that the gas letting had ceased. Problem solved, but man I used a lot of gas during that dive. While I was never in danger, I was a bit disappointed.
A week or so later, Sphyon and I decided to meet at the Blue Heron Bridge. With him in Orlando and me in the Keys, it's a good half way point. I love the bridge and have heard about peeps on rebreathers there seing great things. Well hell, you can see a lot of cool stuff on OC there, but it was worth a try. We could not have asked for a nicer day or dive. The sky was an awesome blue and the park was not that crowded. Met @JahJahwarrior, @crd_kats and Jefferson from Dive Rite in the parking lot, so that was cool too since SPhyon wanted some help with his new Nomad LTZ. That delayed us a bit, but it was worth it. Soon we were walking into the warm waters and finishing up with fins and such.
One of the things I really like about this unit is just how perfectly balanced it is for me. On the bottom, I need just a smattering of air in my BC to be neutral. All I have to do after that is to keep my loop volume constant (minimal). On a normal descent during a deep dive, I let the ADV have fun. It's just so normal and natural to dive my SF2 that way. However, if your target depth is less than 20 ft, you're in for a roller coaster ride with your buoyancy. The minimum setting for my PPO2 is 0.7ata. Simply adding dil above 66 ft is problematic when this is the case. At 20 and above it's a real problem. Most of the dive was done @ 16 fsw so the PPO2 of the dil is about 0.3ata witch depresses the amount of PPO2 in the unit. Now the unit is trying to get the PPO2 up by flooding the unit with O2. That leads to having too much volume in my loop and me starting to be floaty. Consequently, I was constantly exhaling through my nose to keep the breathing loop to a minimum and me neutral. Every now and then, I would exhale a bit too much and the ADV would fire causing the PPO2 to drop some more. Arrrrgh! I'm pissing through O2 like a mad man! So I reached down and simply flipped off the ADV. Oh my. That was easy. Now I'm going through about a bar every three minutes instead of 3 bar every minute. Cool. While I love automation, it's incredibly important to know when to turn it off. If I ever find I need dil, it's easy enough to hit the manual add valve.
Caveat... this was my best dive at BHB. It was magical. We found all sorts of critters and in such quantities that it was amazing. Sphyon would swim behind me and let me scout since the critters weren't spooked by my breathing. I would then call him up to show him the cool stuff. It wasn't all one sided though. He's starting to find a lot on his own, including his first octopus. At one point I saw a one inch blue crab burrow into the sand. I grabbed him and bunch of sand and let the sand wash through my fingers. I held out my hand to Sphyon, he opened up his palm and I released the crab into it. I didn't quite expect the reaction I got though. He acted like I threw a cockroach on him. I was laughing in my loop for a long time after that. It was truly funny.
No matter, I came back up but before I did, I slid the ADV isolator closed. We discussed his equalization issues and called the dive. In the meantime, I noticed that the gas letting had ceased. Problem solved, but man I used a lot of gas during that dive. While I was never in danger, I was a bit disappointed.A week or so later, Sphyon and I decided to meet at the Blue Heron Bridge. With him in Orlando and me in the Keys, it's a good half way point. I love the bridge and have heard about peeps on rebreathers there seing great things. Well hell, you can see a lot of cool stuff on OC there, but it was worth a try. We could not have asked for a nicer day or dive. The sky was an awesome blue and the park was not that crowded. Met @JahJahwarrior, @crd_kats and Jefferson from Dive Rite in the parking lot, so that was cool too since SPhyon wanted some help with his new Nomad LTZ. That delayed us a bit, but it was worth it. Soon we were walking into the warm waters and finishing up with fins and such.
One of the things I really like about this unit is just how perfectly balanced it is for me. On the bottom, I need just a smattering of air in my BC to be neutral. All I have to do after that is to keep my loop volume constant (minimal). On a normal descent during a deep dive, I let the ADV have fun. It's just so normal and natural to dive my SF2 that way. However, if your target depth is less than 20 ft, you're in for a roller coaster ride with your buoyancy. The minimum setting for my PPO2 is 0.7ata. Simply adding dil above 66 ft is problematic when this is the case. At 20 and above it's a real problem. Most of the dive was done @ 16 fsw so the PPO2 of the dil is about 0.3ata witch depresses the amount of PPO2 in the unit. Now the unit is trying to get the PPO2 up by flooding the unit with O2. That leads to having too much volume in my loop and me starting to be floaty. Consequently, I was constantly exhaling through my nose to keep the breathing loop to a minimum and me neutral. Every now and then, I would exhale a bit too much and the ADV would fire causing the PPO2 to drop some more. Arrrrgh! I'm pissing through O2 like a mad man! So I reached down and simply flipped off the ADV. Oh my. That was easy. Now I'm going through about a bar every three minutes instead of 3 bar every minute. Cool. While I love automation, it's incredibly important to know when to turn it off. If I ever find I need dil, it's easy enough to hit the manual add valve.
Caveat... this was my best dive at BHB. It was magical. We found all sorts of critters and in such quantities that it was amazing. Sphyon would swim behind me and let me scout since the critters weren't spooked by my breathing. I would then call him up to show him the cool stuff. It wasn't all one sided though. He's starting to find a lot on his own, including his first octopus. At one point I saw a one inch blue crab burrow into the sand. I grabbed him and bunch of sand and let the sand wash through my fingers. I held out my hand to Sphyon, he opened up his palm and I released the crab into it. I didn't quite expect the reaction I got though. He acted like I threw a cockroach on him. I was laughing in my loop for a long time after that. It was truly funny.
Never trust a man with closed loop and handful of sand. Lesson learned.
I like Jefferson @ DiveRite far more than Pete now for sure.
I like Jefferson @ DiveRite far more than Pete now for sure.
At 16ft why is there dil in the loop at all? Use the 0.7 setpoint to keep the solenoid quiet, but manually add o2 and run it at 1.2ish. As the loop volume drops through consumption you will sink a little. Just top it off with O2 to maintain buoyancy.
OP
The Chairman
Chairman of the Board
OP
The Chairman
Chairman of the Board
You're reading way too much into what I'm writing. I'm maintaining my PPO2 @ 0.7 ata. The ADV was working against me and wasting both dil and O2. Turning off the ADV when shallower than 40ft corrects that. I dove the Benwood yesterday and since it mostly sits at 35 ft, that protocol worked perfectly. I'm headed to do some shore dives in Ft Lauderdale this morning which will also be shallow. Deep is fine, but I like to mix things up.
I've been able to dive a bit more this week on my SF2 and have passed 10 hours. Had a wonderful dive on Conch wall with Rainbow Reef and James Draker from SF2. Saw 29 lobsters a bunch of lion fish and more. Very easy dive and everything worked perfectly.
I've been able to dive a bit more this week on my SF2 and have passed 10 hours. Had a wonderful dive on Conch wall with Rainbow Reef and James Draker from SF2. Saw 29 lobsters a bunch of lion fish and more. Very easy dive and everything worked perfectly.
Oh ok. On a 16ft dive I wouldn't bother adding dill at all and just add O2 alone. Unless you flush the loop a lot, ppO2 will be in the 1.2 - 1.3 range just from the air the loop started with. For 35ft obviously you need to add some dil
OP
The Chairman
Chairman of the Board
That's about how I'm diving it too. Did a wonderful shore dive off of Lauderdale by the Sea yesterday. The SF2 was very efficient. My buoyancy rose and fell with my consumption and addition of oxygen. Very zen.
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