The Octopus Conundrum

[Eric Sedletzky]

Being serious now.

A few weeks back I was diving with a friend up on the coast. We each solo dive off our kayaks and have a mutual understanding that we are same ocean same day divers. A big reason is because we are hunters and hunting is almost always more productive while solo.
Anyway, after the first dive when I cam back to my kayak I learned that he had a freeflow about 15 minutes into his dive in about 60 feet of water and had to do a freeflow breathing ascent where he breathed off the reg sideways. It pretty much emptied the tank except for about 120 PSI when the spring in the second stage was able to close it down. He said he knew what happened right away, had no problems at all getting to the surface, wasn't freaked out in the least bit, and knew exactly what to do. He did have an octo that he gave up on trying to find and just decided it was easier to side breath his primary since the surface wasn't that far away and he knew his air was going to run out soon. He isn't a long hose person, he still uses the scumball and the octo reg came out and was swing around somewhere...
The reg set he was using was an Aeris which was brand new BTW, his wife got it for him (supposed to be rated high by scuba lab).
So back in the parking lot at the truck we decided to do a little testing to find out what went wrong.
When I checked the IP (on a full tank) it fluctuated between purges from 135 up to 152 and would creep to 155. It would stop sometimes at random numbers in between. My hunch is that the second was tuned for 135 to 140 and 155 pushed it over.
I'm wondering, and have a question for reg experts in this thread: Since highly balanced second stages have such a soft spring and are designed to have a very low cracking pressure plus have the ability to easily deliver air at very low tank pressures, does that also mean that they are more prone to freeflows at slightly higher IP's? and do they also tend to drain tanks out more completely than unbalanced second stages since they are pressure assisted? And last, having a venturi opened up all the way to assist in flow would that also have an affect of keeping a flow going down to almost an empty tank?
I'm guessing that if that's true then using a regular unbalanced poppet second stage might be a smart idea since it seems they would be a little less prone to freeflows. And if they did freeflow, would the freeflow stop earlier at a higher tank pressure like maybe 200 or 300 instead of 120? And what about the venturi affect, do you think that plays a big enough part either in combo or alone? I'm just looking at anything to minimize the possiblity of a freeflow since it did happen and does happen occassionally.
I personally have no problems using unbalanced regs, and in some ways think since they are simpler then they also are more problem free... at least with the second stage.

So long story short, I tightened up his second stage, we rigged his octo under his neck on a piece of bungee I had in my toolbox, and we were on our way for our second dive. And yes we did stick together the whole time as buddies.
See, I'm not as big a prick as I may seem.

 

[beanojones]

With equally light breathing second stages the balanced will always handle a high out of range IP better.

The easy way to test this is to use an "overbalanced" first stage, one whose IP goes higher with higher ambient pressure, and try and use any unblanced second stage.

Unless the unbalanced second stage is tuned to not crack until 160 PSI or so (which makes it hard breathing) it will leak (not a free flow but a leak). A balanced second stage uses IP to close the valve so it can stand a broader range.

If you have that swinging IP problem then it was probably swinging higher in the water and caused the explosive free flow.

With almost all hoses bending them like a garden hose is one way to direct flow to a single second stage which can save gas in a blown hose or failed second stage, but in a 200 PSI IP broken reg, that will just cause the other second to free-flow as well.

 

[Eric Sedletzky]

With equally light breathing second stages the balanced will always handle a high out of range IP better.

The easy way to test this is to use an "overbalanced" first stage, one whose IP goes higher with higher ambient pressure, and try and use any unblanced second stage.

Unless the unbalanced second stage is tuned to not crack until 160 PSI or so (which makes it hard breathing) it will leak (not a free flow but a leak). A balanced second stage uses IP to close the valve so it can stand a broader range.

If you have that swinging IP problem then it was probably swinging higher in the water and caused the explosive free flow.

With almost all hoses bending them like a garden hose is one way to direct flow to a single second stage which can save gas in a blown hose or failed second stage, but in a 200 PSI IP broken reg, that will just cause the other second to free-flow as well.

The first stage was an AT600 as I remember. I'm not familiar with that brand so I have no idea what it is other than it appeared to be a diaphragm style. I did also do a test to see what kind of flow it had while depressing both second stages. I wasn't very impressed with the amount of flow, it was very weak at best with both regs barely moving any volume and the IP gauge going down to almost zero.
I'm surprised the balanced second stage is the one that blew and not the unbalanced octo.
I also noticed his reg set had Max Flex braided hoses, which seemed flimsy to me. Overall I wasn't impressed with the Aeris at all, it looked very second or third tier to me.
Not my style, but then I'm not the one using it either.

 

[Doc Harry]

Just curious, how many of you, as a solo diver, still tote an octopus/safe second on your main tank regulator? And why if so?

When solo diving, I always have two separate cylinders (twin back mounts), two independent first stages and two independent second stages.

That being said, sometimes I solo in locations where I cannot get twins, in which case I use a pony. Often I am on vacation with my wife, and I go off for some solo diving while she sleeps on the beach.

So let me ask you a question:
Why should I remove my octo just because I am soloing? Especially when I would have to re-attach the octo when I go diving with my wife. Doesn't make any sense to remove the octo.

An octopus/second and it's fittings do, in my opinion, right or wrong, represent a decrease in reliability.

I also think that you're reasoning is incorrect. You don't use redundant gear because equipment is so reliable, and then you say that you shouldn't use redundant gear because equipment is so unreliable.

Do you see your contradiction?

 

[Nemrod]

This thread is really not intended to argue one way over another, it was a inquiry/conversation into and about what people do and use and why.

You have changed the wording of what I said, I did not say;

You don't use redundant gear because equipment is so reliable, and then you say that you shouldn't use redundant gear because equipment is so unreliable.

I have said that I prefer to simplify and choose proven and reliable gear.

I attempt to reduce to the practical extent, failure points, snag points, etc.

I do not carry multiple items unless there is a specific need to do so.

I prefer to not use redundant systems solo to my general free dive depth dependent upon conditions because under such conditions, the surface is my redundancy. Below my free dive depth and again dependent upon conditions, I may choose redundant systems or may not.

Redundant systems, for a solo diver, do not include an octopus rig which is intended for buddy team redundancy.

Therefore as a minimalist I would be loath to carry an octopus as a solo diver since it serves no useful purpose. And I have stated my thoughts on the usual caveat that I might meet a stranger who needs to share air.

And therefore one of my opening questions, would it seem practical or useful to substitute an Air II (type) system for an octopus and inflator mechanism? ;

Because it eliminates a hose to an octopus I do not need as a solo diver.

But still allows me to share air with a buddy if buddy diving (wife etc. as you say).

And fits within my minimalist thinking because it combines two pieces of equipment into one.

Allowing me to accomplish both solo and buddy diving with minimal equipment and that considering travel (packing, weight and all that).

And yet another therefore;

Is it practical to use such a system for both solo and buddy team diving? That is where this started.

And I have said, I think my questions have been answered.

Just curious, how many of you, as a solo diver, still tote an octopus/safe second on your main tank regulator? And why if so?

N

It is the conflict within my mind on these subjects that you have incorrectly understood, misunderstood, that resulted in my initiating this thread. I wanted opinions and I got some and I thank you for yours.

And going back to your quote, I think you could clarify your thoughts on redundancy? I see a contradiction there and it is not mine but yours.


And, I did not make this clear, the problem with starting a thread and not spending more time to clarify what I was asking. There is boat diving and there is shore/beach diving. I do both. Much of my curiosity was concerning shore diving especially involving walking some distances. And then, manipulating equipment while carrying a camera system and my camera getting banged by the pony rigging and it getting in my way sometimes was also in the mix somewhere if I recall along the way.

Well, it is that time of year that I pile everything in the middle of my "dive shop" and pick out what I will use for the year. Last year I started out with no octopus/second on my main regulator and a slung pony with it's regulator, therefore fully redundant. Then about half way through the season, I went back to my old ways of no pony above 60 feet (arbitrary number that is flexible and dependent upon several factors).

This year I am considering an Air II type device to eliminate a hose for buddy diving and I may as well retain that for solo as it adds no particular clutter (nor redundancy). And this would be with or without my slung pony (depth/condition/whatever dependent). If I had only one set of regs or one SCUBA rig I would do differently but I, unfortunately, have many complete rigs and a huge assortment of gear collected over the years so I am not restricted in any way to a single rig or configuration but rig instead appropriate to the dive and my needs for that dive.

The other consideration is my camera, the pony, frankly, it gets in the way, no way around it. Is it a big deal, not really, but it is there and it can be in the way. Another is weight when walking, when one gets to be 60 plus, it does matter, no way around it. And, my typical cylinder for solo at sport diving depths is a 63 cf. I can have the same or greater bottom time with that size cylinder as do most with an 80 or larger, I simply do not need larger for most diving.

I did not expect a consensus and am not surprised there is not. I am pretty sure the SDI book for solo and the book Solo Diving do not call for an octopus as it does not provide redundancy or at best partial redundancy, that being supplied by an independent gas supply, however rigged (pony, independent doubles, doubles on an isolation manifold etc.).

N

I have ordered a unified inflator mechanism to experiment with.

And, a new set of free dive fins because all divers need another set of fins.

N

 

[beanojones]

What has always been the appeal for me of Air2 type devices is just what you recognize: no extra hose, and yet a backup for a buddy.

The drawback for me of Air2 based system as I see it as other divers use it is the length of the primary hose. However, I have used an underarm octopus length primary hose (with a swivel) ever since I started out with a Sherwood Maximus and Sherwood Shadow.

There are some great advantages to this Sherwood type setup because the breathing devices are still all connected directly and a standard BCD inflator can be used, so for people who want to travel with the system it just means bringing the reg and slapping it on a rental BCD.

Air2's get a ad rap for being tricky because people keep allowing seawater and freshwater into the inlet of the device, when they disconnect the hose from the Air2.

No Reg is designed to be flooded and stay reliable.

Because I like the idea, I have wandered over to the Atomic ss1 which allows the device to be unscrewed from the BCD corrugated hose.

But if I only had one reg set, it would be the shadow plus system as the inflator reg, and not the SS1.

 

[Patoux01]

Well, I'm not completely confident with my knowledge of the air 2, but it looks as if losing your bcd inflator (for instance should it get stuck) also means you loose your backup reg. Am I mistaken on that? If I'm right, no one here has an issue with that?

 

[Basking Ridge Diver]

Well, I'm not completely confident with my knowledge of the air 2, but it looks as if losing your bcd inflator (for instance should it get stuck) also means you loose your backup reg. Am I mistaken on that? If I'm right, no one here has an issue with that?

That is what my Pony is for?

 

[DaleC]

I go with Nemrod's thoughts. To me an AIR2 (like) device is an octo, or rather a back up reg as you would donate the primary.

As for losing your inflator and back up reg. If you lost one would you keep going or abort the dive? What are the odds you will need to donate to an OOA diver as you are surfacing because of a stuck inflator hose?

 

[redacted]

Air2's get a ad rap for being tricky because people keep allowing seawater and freshwater into the inlet of the device, when they disconnect the hose from the Air2.

No Reg is designed to be flooded and stay reliable.

The problem is not so much that sea water gets in as it is the failure to clean it out and dry it before storage. The "inlet protector" needs to be left off during soaking/cleaning and drying and should only be used to protect the sealing surface during transport and storage.

The Air2 inflator mechanism uses an LP seat to make the gas seal rather than a dynamic o-ring sliding past an orifice which leaves it less subject to wear and damage.