Review Diving the Avelo System

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@scubadada The maximal pressure is 4000 psi, correct? What does that come out to in terms of overall ballast capacity? For example, lets say at the start of the dive I need two pounds worth of water (which from what I've seen/read, seems about like what you expect to need), what's the highest fill I can get and still add the water I need?

Also, side note, but what mechanism prevents the water pump from overfilling the tank? Like, does it switch off at 4000 psi, is there an overpressure system, or what?
During training you learn how much weight you need to dive Avelo with a 3000 psi 10L tank. This involves weight checks and post dive analysis. The goal is to run the pump once so that the pressure ends up around 3500-3600 psi. This is 2lbs of water and leaves you neutral if weighted properly.

So here's what you do if you want to dive a boosted tank. You fill it to 3700 or so and it cools off to 3600 or so. Now you enter the water neutral. You do not run the pump to descend. Now clearly this is not for training purposes and as a certified diver you have to understand you are not entering the water positively buoyant.

There is no shut off on psi. If you exceed 4350 psi the tank will be fine but your regs will be at risk of free flowing as your regs are designed with a 300 bar maximum pressure. This is why in training we emphasize looking at your gauge when running the pump. First to ensure pressure is rising and second to ensure you do not exceed 300 bar.
 
@EdMcNeill09 That makes sense. I'm given to understand a regulator's second stages act as built in overpressure valves normally anyway, so it fits. I suppose there is a slight risk that if the pump were to get stuck on you could lose your air that way, but, if absolutely nothing else, this is why we have the buddy system (and I assume you could open the water valve or something to prevent such an air loss as well. Not to mention I wouldn't expect the pump to get stuck on very often.)
 
Thank you, @EdMcNeill09, for your responses in this thread. Avelo has a serious challenge trying to break into a small market with something new, while at the same time overcoming strongly entrenched, firmly held beliefs about buoyancy control.

I am very new to scuba diving - new enough that I should not have yet formed strongly entrenched, firmly held beliefs about buoyancy control since I'm still learning how to control my buoyancy properly, particularly in the shallows at the end of a dive with an AL80 that is getting close to empty. And yet I have been very skeptical of the Avelo system since I first heard of it. The review of Avelo by the OP of this thread (a diver with MUCH experience) moved my needle a little away from "very skeptical", but not very far.

My reasoning was: "Fish use their swim bladders filled with gas to assist with their buoyancy much the same way that we use gas in a BCD to accomplish the same thing. If it's good enough for fish, why are we trying to re-invent the wheel here?"

Any marine biologist reading this (or anyone else who knows more about how the creatures in the sea control their buoyancy) is probably shaking their head ruefully, banging their palm on their head, or pounding their fist on their desk, depending on their temperament. Because, as a little more research has now shown me, that is only part of the story.

My reasoning seems accurate enough - for (most) bony fish. That is indeed how they primarily control their buoyancy (or so I understand - I am obviously not a marine biologist but a pure layman). But my further research indicates that marine mammals like whales, dolphins, manatees (amongst many others, of course) do not have a swim bladder, but control their buoyancy primarily with their lungs (having the advantage of blubber to give them natural buoyancy so they don't have to constantly fight a tendency to sink). And cartilaginous fish, like sharks and rays (amongst others, of course) don't have a swim bladder either - the heavier-than-water oil in their livers allows them to maintain neutral buoyancy at depth (although seemingly they need to depend on hydrodynamic lift to keep from sinking, so perhaps they aren't truly "neutral" after all).

The point being that there are examples in the natural world around us that show that gas in a bladder is not the only way to control buoyancy, and so the initial reasoning that I based my skepticism on was very flawed.

If I were to post that vintage divers (the ones that don't use anything besides their lungs and weight distribution to control their buoyancy while diving) were "wrong" to dive that way, the post would probably get a bazillion "thumbs down" reactions and likely a kindly message from a moderator. And rightly so. I now believe that it's pretty much the same thing as saying that the way that whales, dolphins and manatees (amongst others) control their buoyancy is "wrong". Totally out of line.

Similarly, for me to hold to this belief that using a water-based system to control buoyancy instead of gas is "wrong" is akin to saying that the way sharks and eagle rays control their buoyancy is "wrong". And when I watch an eagle ray soaring 5 or 10 metres over my head, flapping its wings only occasionally if at all while maintaining perfect trim - I'm in awe. So what it is doing can't be "wrong".

I realize the analogy - vintage divers are like dolphins or whales, "standard" scuba divers are like parrotfish or groupers, and Avelo divers are like sharks or rays - isn't perfect. Sharks and rays, for instance, don't have to stop partway through their day and add more oil to their livers to maintain neutral buoyancy. But Avelo technology is still very, very young - and who knows where scuba technology as a whole is going? Sensors that can automatically adjust to trigger an automatic add/release of air or water as necessary are probably within our grasp someday, if they do not already exist.

One thing is for certain - much of our successful engineering as humans has come from observing and imitating what we see in the natural world around us, and there is clearly a basis in nature for a "heavier-than-air" buoyancy control system. So I'm officially reserving judgement, with my needle firmly set in the middle of the road at neither skeptic nor convert, until I can someday try it out for myself.

However, my intelligence and experience are limited, and the intelligence of the two "research assistants" that I used to help me come to my new way of looking at this topic is entirely artificial - clever computer coding made to look like intelligence even though it really isn't. If my new way of looking at the Avelo system is flawed because the analogy is flawed due to flawed research... please, please let me know.
 
From upthread:
When I dive with a boosted Avelo tank I don't add water to descend. I enter the water with neutral buoyancy instead of being 1 pound positive. This is obviously a choice I make and it might not be comfortable for divers who need to be positively buoyant before descending. In my experience it's pretty easy to stay on the surface when neutral.

bottom line is if you are weighted for one pound positive buoyancy with Avelo at 3,000 psi you will be neutral with 3600 psi in your tank. No need to run the pump. In practice some like to run the pump and add another 100psi to become comfortable at the start of a dive.
 
@EdMcNeill09 That makes sense. I'm given to understand a regulator's second stages act as built in overpressure valves normally anyway, so it fits. I suppose there is a slight risk that if the pump were to get stuck on you could lose your air that way, but, if absolutely nothing else, this is why we have the buddy system (and I assume you could open the water valve or something to prevent such an air loss as well. Not to mention I wouldn't expect the pump to get stuck on very often.)
Yes. Exactly. During training we have divers experience a pump failure where the pump adds 4lbs of water. This requires the diver to swim in a slightly heads up position. In real life a diver would probably release pressure as it rose to uncomfortable levels and end the dive. I would add that I don't know of a pump ever getting stuck open.
 
Thank you, @EdMcNeill09, for your responses in this thread. Avelo has a serious challenge trying to break into a small market with something new, while at the same time overcoming strongly entrenched, firmly held beliefs about buoyancy control.

I am very new to scuba diving - new enough that I should not have yet formed strongly entrenched, firmly held beliefs about buoyancy control since I'm still learning how to control my buoyancy properly, particularly in the shallows at the end of a dive with an AL80 that is getting close to empty. And yet I have been very skeptical of the Avelo system since I first heard of it. The review of Avelo by the OP of this thread (a diver with MUCH experience) moved my needle a little away from "very skeptical", but not very far.

My reasoning was: "Fish use their swim bladders filled with gas to assist with their buoyancy much the same way that we use gas in a BCD to accomplish the same thing. If it's good enough for fish, why are we trying to re-invent the wheel here?"

Any marine biologist reading this (or anyone else who knows more about how the creatures in the sea control their buoyancy) is probably shaking their head ruefully, banging their palm on their head, or pounding their fist on their desk, depending on their temperament. Because, as a little more research has now shown me, that is only part of the story.

My reasoning seems accurate enough - for (most) bony fish. That is indeed how they primarily control their buoyancy (or so I understand - I am obviously not a marine biologist but a pure layman). But my further research indicates that marine mammals like whales, dolphins, manatees (amongst many others, of course) do not have a swim bladder, but control their buoyancy primarily with their lungs (having the advantage of blubber to give them natural buoyancy so they don't have to constantly fight a tendency to sink). And cartilaginous fish, like sharks and rays (amongst others, of course) don't have a swim bladder either - the heavier-than-water oil in their livers allows them to maintain neutral buoyancy at depth (although seemingly they need to depend on hydrodynamic lift to keep from sinking, so perhaps they aren't truly "neutral" after all).

The point being that there are examples in the natural world around us that show that gas in a bladder is not the only way to control buoyancy, and so the initial reasoning that I based my skepticism on was very flawed.

If I were to post that vintage divers (the ones that don't use anything besides their lungs and weight distribution to control their buoyancy while diving) were "wrong" to dive that way, the post would probably get a bazillion "thumbs down" reactions and likely a kindly message from a moderator. And rightly so. I now believe that it's pretty much the same thing as saying that the way that whales, dolphins and manatees (amongst others) control their buoyancy is "wrong". Totally out of line.

Similarly, for me to hold to this belief that using a water-based system to control buoyancy instead of gas is "wrong" is akin to saying that the way sharks and eagle rays control their buoyancy is "wrong". And when I watch an eagle ray soaring 5 or 10 metres over my head, flapping its wings only occasionally if at all while maintaining perfect trim - I'm in awe. So what it is doing can't be "wrong".

I realize the analogy - vintage divers are like dolphins or whales, "standard" scuba divers are like parrotfish or groupers, and Avelo divers are like sharks or rays - isn't perfect. Sharks and rays, for instance, don't have to stop partway through their day and add more oil to their livers to maintain neutral buoyancy. But Avelo technology is still very, very young - and who knows where scuba technology as a whole is going? Sensors that can automatically adjust to trigger an automatic add/release of air or water as necessary are probably within our grasp someday, if they do not already exist.

One thing is for certain - much of our successful engineering as humans has come from observing and imitating what we see in the natural world around us, and there is clearly a basis in nature for a "heavier-than-air" buoyancy control system. So I'm officially reserving judgement, with my needle firmly set in the middle of the road at neither skeptic nor convert, until I can someday try it out for myself.

However, my intelligence and experience are limited, and the intelligence of the two "research assistants" that I used to help me come to my new way of looking at this topic is entirely artificial - clever computer coding made to look like intelligence even though it really isn't. If my new way of looking at the Avelo system is flawed because the analogy is flawed due to flawed research... please, please let me know.
Wow. You are a very creative thinker. I've never viewed it like this. I can't speak to your analogy. What I can tell you is that a fish has sublime buoyancy control. Avelo has sublime buoyancy control. An air filled BCD does not have sublime buoyancy control if you change depth more than 15-20'. When I dive Sea Tiger, a wreck here in Honolulu, on Avelo I am neutral at 10' and neutral at 110'. No adjustments needed. And when I say neutral I mean fully dialed in neutral. Not on the edge of good buoyancy. dialed in.
 
---snip---

There is no shut off on psi. If you exceed 4350 psi the tank will be fine but your regs will be at risk of free flowing as your regs are designed with a 300 bar maximum pressure. This is why in training we emphasize looking at your gauge when running the pump. First to ensure pressure is rising and second to ensure you do not exceed 300 bar.
300 bar * 14.5038 psi/bar = 4351 psi Short of a fire department compressor, I've never seen one that will do 300 bar
 
300 bar * 14.5038 psi/bar = 4351 psi Short of a fire department compressor, I've never seen one that will do 300 bar
Nuvair makes compressors that will fill higher than 300 bar "The VOYAGER SERIES from Nuvair are turnkey nitrox generating systems that can pump air at up to 5000 psi (345 bar) or produce nitrox (EANx) at up to 3600 psi (250 bar) to fill scuba tanks or storage cylinders. Voyager systems can deliver up to 17 CFM (481 L/min) of EANx40 (40% nitrox) at 3600 psi (250 bar) and can supply air fills up to 4500–5000 psi (310–345 bar)."

I suspect that most shops compressors are capable of higher PSI fills than they limit them to. I"ve not explored the topic. I suspect though that the limiting factor at most shops are the yoke whips they use to fill tanks and the standard expectation of a 3000psi fill. Yokes are not rated for 300 bar. I can't recall off hand what the limit is.
 
TLDR of my previous post and this one: No longer an Avelo skeptic, but not yet a convert.

No adjustments needed
Even as a new diver, I understand the appeal of this. On my last dive trip during my own dive to a wreck just a shade deeper than 100' I had to adjust ever so slightly the amount of gas in my BCD at a few points throughout. I didn't have to think about it too much - I had excellent instructors who taught me the value of a very light touch when making the adjustments and it is gradually becoming more instinctive. But I can see that to not have to think about it at all (other than one or perhaps two adjustments to the amount of water in the hydrotank due to the amount of gas breathed) would be liberating.

"Sublime" is not a word that I use very often (and my command of English sometimes is questionable these days), but using a dictionary that gives one definition of it as "tending to inspire awe usually because of ... transcendant excellence" I fully agree that fish (bony and cartilaginous) and marine mammals indeed have sublime buoyancy control. They are awesome, which is only to be expected, since they are in their natural environment. The fact that their methods of achieving it differ so greatly now convinces me that there is also more than one way for humans to control their buoyancy in what is for them an unnatural environment.

I have been taught to control my buoyancy underwater using my lungs (like any other self-respecting mammal) as well as a bladder that can be filled with varying amounts of the same gas that I am breathing, in a very poor imitation of what bony fish like parrotfish and groupers do. I am still rookie enough that my amatuerish efforts of doing so are sublime for me, and I expect that to only improve as I continue improving with that system.

The experiences that scubadada and the impressions of the other "ScubaBoard Avelo guinea pigs" who have tried out the Avelo system have posted in the forums, your informative responses to questions and challenges raised in this thread, and my own research have convinced me that if the Avelo system becomes available in the region where I dive and the cost of trying it out is in my budget I would now be more than willing to try out a system of buoyancy control using my lungs (like any self-respecting mammal) as well as a tank that can be partially filled with water, in a rather poor imitation of what cartilaginous fish like sharks and rays do. If that happens, I may very well come to the same conclusion that you have - that it is even more sublime than the currently "standard" method of human buoyancy control.

Of course, my research also kind of makes me want to try out controlling my buoyancy while scuba diving using only my lungs and proper weight distribution, just like self-respecting whales, dolphins and some vintage scuba divers do. I think it would mean somehow getting my hands on equipment that is seemingly no longer easy to come by, and a lot of training from individuals who live very far away from where I dive so that I did not kill myself in the process. But I'm wondering if perhaps for humans that isn't the most sublime way of diving of all...
 
I recently noticed that Ocean Enterprises in San Diego has become the newest Avelo Dive Center. Avelo already had dive centers on Catalina Island and in Monterey, California.

I also see that the Avelo Tour recently finished at one dive center in Los Angeles and will be starting at another later this month.
 
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