Review Diving the Avelo System

[SouthernSharktoothDiver]

@scubadada @lowwall These explanations make sense. I thought a while ago that Avelo might be better off using a second tank for buoyancy management, so that your airfills are not tied into your buoyancy system. I did a little research, and found I invented the Dacor Nautilus. Sigh. Someone always steals all my good ideas...decades before I have them.

Presumably the technology does not currently allow for a system with larger air capacity without losing either streamlining or the light weight that is the major advantage Avelo lays claim to, but as always, technology progresses. Assuming Avelo gains a strong enough following to warrant a 2.0 version in a decade or two, it will be interesting to see what new advances in materials science, manufacturing, and pump/battery design might allow. Still, for the moment at least, it does look like there's a definite upper bound on how much air avelo can carry without becoming heavier and bulkier than a standard setup.

I did have one question: if someone were to dive Avelo with a sidemounted AL 80, would the system be able to adjust for that? The AL 80 would presumably change your buoyancy by about 5 pounds over the course of the dive, as well as the several pounds of change due to the air in the hydrotank, for perhaps 8-10 pounds of buoyancy shift. As I understand it, Avelo typically can only adjust for around 4-6 pounds of buoyancy, but I thought perhaps if you breathed down the hydrotank first, you might could take on additional mass as the air volume in the tank is now lower. However, I feel like at a certain point you might run into safety concerns, or the inevitable issue of only have so much space to pump water into.

Thoughts?

 

[scubadada]

I have not dived Avelo off a boat. I have seen Avelo off a boat and assume the tanks fit into normal tank slots

 

[Trailboss123]

I have not dived Avelo off a boat. I have seen Avelo off a boat and assume the tanks fit into normal tank slots

Did you ever in your wildest dreams think that your Avelo post would generate 66 pages of Scubaboard content? Totally amazing

 

[inquis]

I did have one question: if someone were to dive Avelo with a sidemounted AL 80, would the system be able to adjust for that?

Short answer: probably, but I suspect for reasons other than what you're thinking based on your post.

Details:
At the beginning of the dive you would want to be positively buoyant by +2 lb. Assume this is possible. If you consumed all the gas in the Avelo tank, there would be room for an additional 9 L of water or 20 lb of ballast (ignoring the space the bladder takes up for simplicity). That's the equivalent of about 250 cuft of gas you could conceivably take with you and consume while still remaining neutral.

The difficulty lies with that initial assumption. For the normal Avelo system, the "fixed parts" (cylinder/plate/pump/batteries/lead/diver) have some buoyancy (call it X1), and we know the total buoyancy will be +2 lb. Since X1 - 6 lb (Avelo gas weight) = +2 lb, we see that X1 = +8 lb. If you add an AL80/reg, the fixed buoyancy will increase by +2 lb (assuming +4 lb empty tank in salt water - 2 lb reg), so X2 = +10 lb. The total buoyancy will then be: B2 = +10 lb (X2) - 6 lb (Avelo gas weight) - 6 lb (AL80 gas weight) = -2 lb.

That's a problem, but possibly not insurmountable. If you had added lead to the system, you could just remove 4 lb of lead, and you're back to your target +2 lb starting buoyancy. Enjoy the additional bottom time and watch that NDL.

If you didn't add lead (e.g., you are diving without a wetsuit), what do you do? Avelo already solved this issue by making "buoyancy pads" (I believe out of plastic) that can be attached to the system to increase its buoyancy. (Search upthread, and you'll run across mention of them.) The crucial question is whether those pads can add 4 additional pounds of buoyancy. You're looking at a volume increase of at least the size of a 2L soda bottle (not even counting the weight of the plastic). I have no idea how much buoyancy those pads add or how many attachment points are built-in.

Another option might be to use a more buoyant tank. Connecting the dots, you may guess this is why Avelo chose the carbon-wrapped cylinder in the first place. It wasn't just for the "cool factor".

Bottom line: I believe a side-mounted AL80 would work with Avelo in most cases. Weighting will be CRITICAL to safety and successful usage, but that's already the case for the normal system.