Review Diving the Avelo System

[gordonscuba]

Fair point, but at least you have the option/possibility. Hence why I asked if Avelo's weight was ditchable. If so, I could definitely see a panicked diver going "Oh shoot, I'm sinking!" and dumping weight, thereby saving themself from sinking.

What do you mean "Avelo's weight?" Avelo is a tank with integrated buoyancy control. The diver is free to use a weight belt if they need one (I didn't). Yes, weight belts are ditchable.

 

[SouthernSharktoothDiver]

@gordonscuba The promotional footage/images I've seen show weights strapped on to the based of the hydrotank. Obviously you can wear a weight belt with any buoyancy system, but there are also pockets, at least on some, and I was wondering if Avelo's system for mounting weights on the hydrotank was designed for in water removal. Looking at the pictures, I feel like you could reach it with a little work, from there it's just a question of how easily it comes off/out.

Tank mounted weights are usually located there for trim, as I understand it, and I've never seen ditchable trim weights, so it wouldn't shock me if Avelo's weight mounting is non-ditchable.

Not a huge difference either way, of course. I'm just curious. I suspect if someone were to load down a massively excessive amount of weight, they'd end up putting at least some of it in place they could reach, if only because it has to go somewhere, thus allowing them to ditch some fraction and stop a sink. Whereas if someone who was neutral at 0 put the 3/4lbs the tank weight system usually seems to hold (based on user comments on here), they could overcome that by finning up and buying their dive buddy a beer later in atonement.

 

[inquis]

They say the hydrotank can hold up to 300 Bar, but then in practice you can't fill it that high cause you need to leave "room" for the water ballast. So is that, 250 Bar? 200? I don't think you're get much more air in the biggest tank than an AL 80

Your intuition is spot on. Allowing just enough room to take on 2 lbs of water for ballast, I calculate the 10L cylinder would be at 255 bar to start, including adiabatic heating and compressibility. This is about 8% more gas than an AL80 at rated pressure. (FWIW, an HP100 holds about 29% more than the AL80.)

 

[SouthernSharktoothDiver]

@inquis To be fair, I don't think the company/the people talking about it are trying to be deceitful. Most of the posts I've seen have been very clear you have to leave room for the water, though I haven't heard anything about what the "standard" Avelo fill is. I assume they have a rated pressure they fill to so the system can function properly. Someone who's actually dove it might could say what that is, if it does in fact exist.

 

[gordonscuba]

@inquis To be fair, I don't think the company/the people talking about it are trying to be deceitful. Most of the posts I've seen have been very clear you have to leave room for the water, though I haven't heard anything about what the "standard" Avelo fill is. I assume they have a rated pressure they fill to so the system can function properly. Someone who's actually dove it might could say what that is, if it does in fact exist.

The system is typically filled to a pressure allowing it to provide similar bottom time as an AL80. It's been a while, so I no longer recall the exact pressures, but IIRC that pressure was around 3300 - 3400 psi. It is known that the system can work at higher pressures than that (apparently the pump is quite powerful and has no problem counteracting the pressure of the bladder), but overfilling it just to get a few more minutes is kind of missing the point. This isn't a gas extending tool, it's a buoyancy control tool on which you definitely won't have shorter dives than whatever you currently have on a single AL80.

 

[CT-Rich]

@inquis To be fair, I don't think the company/the people talking about it are trying to be deceitful. Most of the posts I've seen have been very clear you have to leave room for the water, though I haven't heard anything about what the "standard" Avelo fill is. I assume they have a rated pressure they fill to so the system can function properly. Someone who's actually dove it might could say what that is, if it does in fact exist.

My understanding of the system is that you fill the tank and the bladder expands to the full volume of the tank. What the fill pressure is I don't know, but, when you get in the water, you use the pump to add water to the tank (outside the bladder). To get that water in, you have to further compress the air. That is where the 300 bar comes in. As the tank runs down the air, you can add more water to offset the mass of air being expelled, thus keeping the diver neutral throughout the dive. The mass of air inside a 10 Liter tank is about 4-5 lbs (2 kg). From the descriptions I've read, the system is only designed to offset about that much water.
Warm water diving, where you are only using a rash guard, you should be able to get in the water and be able be neutrally buoyant (balanced rig) and stay that way throughout the dive with minimal adjustments.

This pretty much what you do with a BCD except in reverse. Start with aproximately 5 lbs of Air in your BCD, dive with minimal adjustments and end the dive with an empty BCD and neutrally buoyant at the end of the dive.

The place where I see fault on this system is when you talk about anything that is not a tropical reef bumble. If you are wearing a wet suit, you will lose buoyancy with depth. A typical BCD can provide 20 or 30 lbs of lift. Even a full 3mm wetsuit might exceed what the Avelo is capable of doing on 80' dive.

It seems like the system is a solution looking for a problem to solve. If you have back issues, the simple solution is to don and doff gear in the water, not rent $4000 of gear to save ten pounds. A conventional BCD will absolutely give you more buoyancy on the surface in virtually all scenarios. BCD failures do occur, but most of them have pretty easy to follow counter measures.

 

[SouthernSharktoothDiver]

@gordonscuba Yeah, at 3300-3400, that's about matching what my local fill guy does on an AL 80. Given that Avelo is somewhat less frilly/more streamlined than your typical rental jacket, it does make sense this would extend dives or at very least, not shorten them. That being said, I remember my first blue water "tourist" dive, and I'd have happily eaten an urchin for another five minutes, so I think the greed for bottom time might surprise you (of course, that was my first dive post-open water, and I think my SAC was well above 1 cu ft/min all things considered, so perhaps it would be better now.)

@CT-Rich This matches what I've heard as well. I think you could offset more than 4-5 lbs if you wanted to, but you might need less air to do so. As for the wetsuit issue, I actually saw a claim from the company that say, a 7mm suit, doesn't actually lose all that much buoyancy with depth. I've heard many here claim otherwise, but given that I'm diving an old 3mm ski suit I found in the back of a closet, I can't speak from experience on that one. I never seem to lose much on my 3mm, but it's also so crushed by now I doubt it has much give left in it. Perhaps Santa will bring me a nice semi-dry for christmas!

 

[Wibble]

Start with aproximately 5 lbs of Air in your BCD, dive with minimal adjustments and end the dive with an empty BCD and neutrally buoyant at the end of the dive.

Struggle to understand how the complex Avelo system with valves, pump and battery can be lighter than an aluminium backplate, wing and ali80 with 4 pounds of weight in pouches (which I used on my last warm water dives).

The great benefit of a BCD — wing or poodle jacket — is the additional safety of 40-ish pounds of additional buoyancy more-or-less instantly available to keep your head well above the waves at the start and end of your dive. Not to mention if you need that reserve buoyancy for rescue or recovery scenarios (e.g. lifting the shot grapnel out of the wreck; lifting and controlling a diver in a rescue ascent).

 

[inquis]

The system is typically filled to a pressure allowing it to provide similar bottom time as an AL80. It's been a while, so I no longer recall the exact pressures, but IIRC that pressure was around 3300 - 3400 psi.

Filled to 3380 psi (233 bar), it would have the same amount of gas as a full AL80 (77.4 cuft or 2192 L, 6.2 lbs or 2.8 kg).

 

[SouthernSharktoothDiver]

@Wibble I mean, I haven't weighed the system, so I'm not sure, but to play devil's advocate for a second, I'd guess that, since the batteries, pump, etc are dense, you need less ballast weight. From there, since you're effectively adding weight/reducing density after you get in the water so you can skimp out on a bit more lead. Lastly...yeah, most of the comparisons are to "poodle jackets" so as I've said above, I feel like a minimalist setup could likely match or beat Avelo on weight.

As for the reserve buoyancy...they claim to have done rescue scenarios that say it's fine? I don't know a lot about that, as I'm not a rescue/safety diver. I do know the system comes with a "horsecollar" dsmb, but IMO, yeah, what you're pointing out is part of what reduces the versatility of the system to being limited to one type of diving.