SCUBA PROJECT

[johnb]

Hi! i'm a university student from the uk and am hoping you can spare me a second of your time!

For my product design degree project i'm attempting to streamline the aqua lung. I'm looking at reducing the amount that the air supply proturudes from the divers back. The reason why i'm hoping you'll read this post is because i know cave divers have probably the best technical understanding of scuba diving as a whole. I personally have only a basic understanding and am hoping some of you could offer me a little of your knowledge.

My first ideas revolove around the concept of breaking the large backmounted tank(s) up into an arrangemnt of smaller ones (10-15 cubic feet), that could be arranged in a strip down the back. They would ovbiously have smaller diameters and protrude less, but when combined could provide the same amount of air as a large tank. Could such a valve arrangemnt even be produced?? Is it viable?

I would really appreciate any comments you might have, good or bad!

Thanks alot!

John

[medic2230]

HI John

Welcome to the forum. With multiple tanks and manifolds you would be creating more failure points for your air supply. You would also have a lot of task loading if you had a failure on a system like that.

Murph

[Dave Lizdas]

hello john.

How small would our tanks be if they contained liquified gas?

Of course, a greater challenge is to find someone who would actually dive it first... anyone? :D

[DeepSea]

You may want to investigate side-mounting. It seems that has already accomplished what you are looking for. Also, remember that we usually dive doubles. So splitting the tanks up would mean 4 tanks?

[GCT]

Hi John,

It's great that you want to streamline dive gear for your design project. I would have to agree with Murph, adding more manifolds or "failure points" to a tank system wouldn't be the best idea. If you look at it by the numbers making the tanks 10 to 15 cubic feet, you would need 10 to 13 of these small tanks to produce the volume of gas needed that most cavers will want. Keep with it and hopefully your project will evolve into something very useful. Keep us posted. 8)

Tucker

[NitroxWarrior]

Sounds like a good idea, you would have to set the tanks up like a parrallel circuit, so if one valve wasnt functioning you could still get air from the tanks on the other side of that tank.

[mswicord]

This concept was produced by USD in the late 60's early 70's. The tanks (3 of them) were placed in a hard shell case. The concept did not stay around long.

Mark

[Moonfuzzy]

I believe I saw a picture of Gary with this set-up... three 60cuft tanks manifolded together?

[Alan Garrett]

And I don't even want to THINK about all the extra hassle and expense of VIPs, hydros, and O2 cleaning all the extra tanks and hardware. Also, I would think that the turbulence and drag created by water flowing around and between a larger number of smaller cylinders, along with the inevitably complex manifolding hardware, would be less hydrodynamic than a couple of standard cylinders and a single manifold, or in the case of sidemounts and back-mounted independents, no manifold at all. The cylinders currently in use, although heavy and bulky, really are a fairly efficient shape for moving through the water. They share a fairly similar profile to modern submarines. I think in order to really slick things down you should shelve the idea of open-circuit SCUBA and look at some of the newest rebreather technology out there. I think they present a whole new realm of possibilities for someone looking to downsize or streamline diving equipment. I'm no rebreather expert, but a lot of folks on this forum have a lot of experience with them and are qualified to offer some pretty informed opinions. ;-)

[curtschu]

How about looking at the manufacturing process of the tank itself.
What about changing the shape of the tank maybe like a turtle shell shape. The only thing I have not worked out yet is the BC and of course how to make it. But then thats what engineers are for right?

[Genesis]

The triples mentioned are AL30s - I have a friend with three sets.

He was forced to retire them last summer after the Rennaker incident - nobody around here will fill them any more, since they were all 6351 alloy.

Its a bizarre setup. Custom manifold and band system, along with a custom backplate/BC system. Cover/enclosure optional. Single outlet, one "K" valve on the end of the manifold. The manifold and bands are "bent" to go around/on your back.

90 cubes in a nice compact package, but the hydros and vis's will kill you!

He got 'em nearly free when USD stopped marketing them - they didn't sell well as the setup was very expensive.

[johnb]

Thanks for all your replies,

The reason why i started on this project was because my friends father, who was a keen and experienced diver, died on a dive last year . It was hard to get a picture of exactly what happened, it seems like he got part of his equipment snared when swimming in a confined environment, which caused a fatal malfunction in his breathing equipment!

My aim is to reduce the chances of this kind of accident happening. It seems like my initial idea to perhaps reduce the extent to which equipment protrudes isn't really feasible, and i'm greatfull to you for telling me that! I am however still keen to stick with this project.

You guys can probably have a better guess at what part of his equipment got caught and what went wrong on the dive than i can. Is there a part of the system that is exposed and relatively unprotected? If so would like to tackle that, perhaps with somekind of universal cover? Can you identify any such problem areas? I don't really know where i'm going with this project as yet, but i'm really keen to hear what you have to say about it.

Thanks again!

John

[crazyduck]

John,
I am sorry to hear about your father’s friend and your loss; these things can be very frustrating at times. I lost someone and the pain crawls out of the woodwork at the worst possible times. However, I have found that pain is a type of motivation that no one can touch; deep down you want to do something and that is perhaps the most important part of channeling your energy. Always keep it positive!

You may find that education is where you can do the most good. There are associated costs with building, designing, and distributing equipment. I have found that education requires none of these manufacturing costs but instead your time, compassion of what you are looking to bring to peoples attention. If you can educate or illuminate one person that may save that persons life or provide them with the knowledge that what they are doing is potentially dangerous. While this is far from glamorous it is essential. I would not start a campaign of fear but instead provide alternatives or things that need to be taken into consideration by the diver.

If you want to look at gear development I would start by contacting local representatives of gear manufactures and see what they are up to with new products. While they are far from interested in bringing in someone’s idea sometimes it is easier to effect development and change from within the corridors of power.

Since you mentioned that this gentleman lost his life in a gear malfunction something to consider is how many divers carry bailout? Instead of designing a new system would you consider a simple addition to an existing one that uses and applies existing materials? For dives over 100ft a simple Aluminum 40 Cu Ft. tank would provide the diver with alterative to get them safely to the surface. A lot of folks here say they take “Al” with them while diving. Al is not a person but an extra Aluminum tank; and a built in safety factor. Something to think about.

Keep chipping away at it.

Regards, Andrew

[Alan Garrett]

One of the main attributes of cave/technical diving gear configurations is being able to reach around and locate your valves and hose connections by feel in the event of a leak, free-flow, or blown seal. This allows us to isolate the problem and shut down a regulator or tank if necessary. It would be very difficult to conceive of an enclosure for the tanks, valves, and regulators that would still allow a diver to accomplish this. I guess there's no "free lunch" when it comes to stuff like this. It seems every time someone comes up with a fix for one gear problem it usually creates another one, or makes an existing problem worse. :? Looks like you have your work cut out for you! Good luck though, and we're always glad to help in any way possible. :)

[curtschu]

You are correct that we need access to the valves but most of the time it is because the valves are exposed that we need to get to them. IE: Rolloffs ceiling strikes, Etc. I have read every IRAP report and I'm amazed at the number of rolloffs. That would be the Design Winner! Some type of streamlining cover that would still allow you to turn off a freeflowing reg post.

[Dave Lizdas]

Sorry to hear about your friend's father, John. We try to minimize risk but it never goes away.

The valves on a manifold for a set of backmount double tanks (twinsets) stick out to either side and can be turned by ceiling contact (rolloff.)

Wouldn't the chance for rolloff be reduced if the valves pointed up, like the isolator knob in the center? Has anyone heard of an isolator rolloff? This might make them easier to turn - if the regulators dont get in the way. just a thought.

They sure would look strange, but it would be harder for folks to pick up your doubles by the valves.

[mswicord]

Look at the valve on SCBA bottles used in the fire service. They have a rachet like device that prevents roll offs. The problem with this on dive gear is you can not rapidly turn it off if the need arose.... I see a design opportunity here.

M

[NitroxWarrior]

This comes back to a post I made earlier, how about designing a good manifold cover.
One that offers decreased drag, more valve protection but still allows you to turn your air on and off easily, and prevents guide lines from getting tangled in it.

[NitroxWarrior]

The triples mentioned are AL30s - I have a friend with three sets.

He was forced to retire them last summer after the Rennaker incident - nobody around here will fill them any more, since they were all 6351 alloy.

That whole think really sucked, I had a pair of 80 cubic foot tanks that I had to cut the tops off of and use as holders for my welding rods...

http://img25.exs.cx/img25/5899/butcheredtank9og.jpg
almost brings a tear to your eye

[curtschu]

Is this stamped in the tank I have some older tanks I need to Hydro and want to look before I even bother

[jonnythan]

Every time you make the volume contained within a cylinder smaller, you're reducing the gas/metal ratio. 10 small tanks of 10cf would certainly have considerably more mass than 1 tank of 100cf, negating any benefits of streamlining.

[johnb]

A manifold cover that is steamilined, prevents rolloff, but in no way prevents you from accessing the parts of it that you might need to during a dive ...Sounds like a challenge. I'm gona give it a go.

Thanks for all your input, i'll probably be back in a few days posting up a few inital sketch ideas.

Thanks again, really appreciate it

John