Diving Sidemount Rebreathers

I'm explorer Jill heiner's come join me for another into the planet adventure video [Music] [Music] hi I'm Jill hi earth today I'm going to talk a little bit about sidemount rebreathers if you're considering one then I'm going to talk about the differences between a side mount and a back mounted rebreather the different risks associated with each configuration I'll share with you some of the things that I think are really important to know if you choose to take up side mount CCR diving specifically an in-depth talk about work of breathing and finally I'll give you some of my conclusions so let's have a look at the Liberty side mount rebreather it weighs 48 pounds when it's ready to dive with the scrubber the tanks and everything else if you take it apart and put it in a Pelle air case the whole thing ships in the 23 kilogram limit that's perfect for air travel out of the box it's completely neutral which is really nice now why would you want to dive a side mount rebreather as opposed to a back mount rebreather I mean some people are really just interested in the fact that this is you know one simple unit that you're gonna be able to just clip right on your body with two quick clips so it's it's kind of simple in that configuration you use a standard side mount rig and so this is instead of one of the tanks and then on the other side you wear a bailout tank and you come up pretty trimmed if I use this with a dry suit with lightweight undergarments and a steel tank on my left side I'll wear about a four pound weight on my right just to counterbalance the steel tank if I'm just wearing an aluminum tank is my bailout tank I don't need any led at all and I might just be a hair light in a dry suit but in a wet suit that's totally fine and well trimmed a lot of people are really interested in sidemount rebreathers because the the trim is really nice when you're horizontal you're absolutely horizontally trimmed in the water and you're just literally hanging there as opposed to when you're in a background rebreather there is you know quite a shift as you move buoyancy wise from horizontal to head up and feet down so this is really appealing to a lot of people who want to go through small spaces cave diving and dive in complete horizontal trim like I mentioned you've got two clips one that's gonna clip right on the sort of hip to the rear of your side mount rig and the top one will clip somewhere on the chest harness I actually take an extra bungee so the bungee that's on the side mountain harness and I pull it around the valve on the top of the rig and what that does is it really pulls the rig close to my body and that's incredibly important in a side mount rebreather so the whole thing is like held together on this stainless steel frame I think they make it titanium one two and so it's a little bit taller than a tank the mouthpiece itself comes up and into your mouth and the cool thing about this rig one thing I really like about it are these injection lovers here for Dillian and for oxygen it's to me a really easy way to to reach your manual injectors and it makes a lot of the diving skills really intuitive you know exactly where the gas is coming from and where it's going to when they're sitting up there right by your mouth now if you're gonna dive a side mount rebreather any side mount rebreather there's a couple of things that you should know they're easier to flood now when this is in your mouth you can see that there's a straight line of travel right down through the breathing loop through the counter and down into the stack what that means is that if your mouthpiece breaks like if the tie wrap breaks if it's dislodged someone kicks it out of your mouth then the water has a really easy fast path all the way down to the canister in a back mounted rebreather with over-the-shoulder counterlungs if the mouthpiece is kicked out of your mouth then the water will travel down the exhalation hose it'll hit a water trap and then generally drain down into the front counter lung and then you're able to get rid of the moisture now you can still get rid of moisture in this rebreather here so you do have a dump that allows you to get rid of a little bit of moisture but if you've had a major flood it's very possible to get water all the way down into the canister and that's not just with this model that's with any side mat rebreather another risk though to think about is how the work of breathing changes between a back mounted rebreather and a side mounted rebreather so on a back mounted rebreather the entire breathing loop is much better and closer to the centroid of your lungs so that's the very middle balancing point for inhalation and exhalation it just simply can't be on a side mounted rebreather because even if you've got it right up under your armpits you've got tanks and counterlung there that are pretty close to your lungs but then you've got the canister all the way down at your hip so depending on your position in the water that work of breathing is going to shift dramatically from hydrostatic pressure so head up is going to be completely different than a head down horizontals gonna feel pretty good because the counterlung and the canister are at least in line with your body but you're probably going to find overall in normal you know swimming positions a little bit of head up that you're going to have a bit of a tougher in now at the bottom of the inhale so that's characteristic of all sidemount rebreathers now we're cat breathing is not just hydrostatic effect meaning your body's position and that relationship between your lungs centroid in the center of the breathing loop on the rebreather we also have an effect caused by resistive effort within the breathing loop resistive work of breathing is the gas passing through all the different twists and turns and corners and valves and as it does so that slows it down speeds it up creates turbulence so there's a work of breathing associated with that resistive circuit you know it's much like if you yelled fire in a movie theater and everyone got up and and tried to run out the door and start tripping over each other and and blocking the door that would be a poor resistive work of breathing but if you told everyone to get up calmly and walk towards the exit and please leave the theater and they did so in an orderly fashion that would be a much better resistive effort in terms of work of breathing so all rebreathers have the the resistive work of breathing as well and so you know in a rebreather like this you have some you know additional resistant effort at this 90 degree turn for example and where the mushroom valves are but but the resistive effort is also important in creating a certain gas velocity that allows for the gas to stay in contact with the scrubber for a sufficient dwell time in order for the scrubber to have an opportunity to do its job so there's a lot of engineering that goes into all of that the bottom line though with a sidemount rebreather is that so far there isn't one that can pass the ce-1 for one for three specifications for work of breathing on rebreather it's physically impossible and that's really due to that whole length and the impossibility of getting that completely balanced around your lungs centroid so what does that mean for you it means that your rebreather no matter what side Matt rebreather you have is not passed seee meaning it's not passed a specification that's been deemed appropriate for life support so that sounds a little scary there are lots of rebreathers out there that are sold at least in North America without seee ratings at all and these are back mounted rebreathers - so when you're stepping into a side mount rebreather you know that you're going to have an increased work of breathing no matter what the deeper you take that the more problematic that that can become in terms of carbon dioxide buildup something that we don't yet have sensors for inside metal rebreathers so that means that you're really a test pilot in a way and you have to acknowledge that even in the 40 meter range this isn't gonna pass the CEO of breathing nor is any other side memory breather so is that it was risk that you want to take that you're willing to take you know do so with the knowledge that that that that's what's going on here it's physics and we can't beat physics so I think that's important for people to know and I think that's important to decide whether the you know streamlining the sort of ease of transport and everything else is is worth it for you if you do choose to use a side mount rebreather I've been using this for almost a year now the Liberty side mount and I've had a really good experience with it honestly you know between you and me I'm still a little leery about those deeper dives no this is fully equipped for deep dives with to helium sensors for oxygen sensor is an amazing you know interface between the the computer handsets and so it's equipped but but I'm nerv because you know if I have a really high workload situation or a non-optimal you know swim and trim position then that could create a work of breathing issue that creates a carbon dioxide buildup and so it might not be the safest choice for me for those really deep dives but as I was saying I've had a really good experience with this in the last year and have really enjoyed the simplicity of just throwing it on like a tank or if I'm on a project where I dive some rebreather dives and some open circuit dives I can easily switch from side mount to CCR just by putting on a tank instead of the unit so if you want to learn more about the Liberty side mount check out the company dives soft they're the distributors for the rebreather they have a back mounted version as well and full disclosure they have loaned me this rebreather and so I'm just giving you my my feelings and thoughts about it so far but I didn't buy it so I think it's important to disclose that in the video too thanks for joining me it into the planet videos don't forget to click the links and subscribe you'll be supporting our Channel

Channel: Jill Heinerth

Views: 13,531

Rating: 4.9086757 out of 5

Keywords: sidemount rebreather, sidemount CCR, Liberty, Divesoft, rebreather diving

Id: 8HFbn5j68tY

Length: 12min 53sec (773 seconds)

Published: Sun Mar 10 2019