Noob question: Small triples or doubles?

[Kendall Raine]

Exactly.

The challenge I'm having is wrapping my head around all the tech lingo with regards to my question.

What I truly want is a stream;lined setup to run 32/36 nitrox with my poseidon regs attached.

May sound a little out there, but I have my reasons - I figure the smaller doubles or triples will be better balanced and save wear and tear on my back.

As for doubles vs. triples, I think you'll find small doubles are the way to go. The only triple manifold of which I'm aware was made for a short time by/for US Divers. This was in the early 80's, I believe. There was no redundancy in that manifold. It only took one regulator and had a yoke fitting. It came with triple 30's and made you look like a Jacques Cousteau wannabe. Then there is the issue of banding them together if you can't find an old US Divers set-up. I doubt very much it was lighter than a single aluminum 100. Other than e-bay, I don't know where you'd find one. You could call around dive shops to see if anyone has seen such a set, but other than starting some interesting conversations I think you're looking for a needle in a haystack. I haven't seen one in 15 years. Some designs such just be allowed to die.

The double set up allows you to use two regulators, an isolator manifold, or run independents, and have a high degree of redundancy. The isolator can be fitted to a large variety of tanks, steel or aluminum, if you later decide you want a different capacity. It can also be sold if you don't like it. Running independents has its own benefits and drawbacks. If you go that route, you'll want a left handed (offsided) DIN K valve, but it's certainly the quickest and cheapest solution.

 

[WD8CDH]

Ron,

Welcome to the board and congratulations on your first post.

Thalassamania and TS&M are two different individuals. The former has inserted a quote by the latter into his "signature line", or the space beneath each of his posts.

You are addressing a post made by Thalassamania, not TS&M. (But he will likely forgive you and not flame you too severely!)

I admit to curiosity, and thus will inquire of you:

What benefit do you perceive from diving triples - three skinny tanks - over a set of doubles (specifying a set of 8" steel tanks such as PST E8 130s, for example)?

It would appear at first glance that there are drawbacks (costs of O2 cleaning/VIPing/Hydro-ing 3 tanks as opposed to 2) that are not offset by any advantages that I can identify.

So I'm curious as to what you consider advantages of "triple tanks"?

Thanks, and again, welcome to ScubaBoard.

Doc

Hi Doc,

Thanks for the welcome. My diving experience is probably a little different than most. I started in the 60's doing both commercial and sport diving. Much of my commercial diving was confined space. I had to have equipment that felt part of me rather than me hanging below the equipment. I've never really felt comfortable diving anything bigger around than a standard 71.2 (6.9"). I found double 38s or 40 to be more manouverable than a single 80 or even 71.2.

Double 71.2s or triple skinny 40s or 45s is kind of a toss up depending on the dive. I usually prefered the triples when manifolded as doubles with an independant third tank. It fit the 1/3 in 1/3 out 1/3 for emergencies real well. For a while, I used a tripple manifold with isolators between the tanks and and kept one of the tanks isolated off as the 1/3 for emergencies on "tech" dives or opened for more capacity in shallow open water dives.

I no longer have any of the old skinny steel tanks so all of my doubles and triples are now made from aluminum 30s 35s and 40s with custom manifolds.

It's interesting to note that 4.5" to 5.5" diameter is structurally a sweet spot balancing tensile strength, wall thickness and bouyancy for about 3000psi service at least with 6061-T6 aluminum. If you look at Luxfur S40 tanks and S80 tanks, you will see that the bare 80 cuft tank weighs more than 2 - 40 cuft tanks. Lifting two 40s is also easier than liftine one 80, at least for me, the 40s don't drag with my arm straight and the 80 does.

An interesting rig if you need a pony is a set of 40s on a standard wide spaced manifold with a S19 or shorter small tank tucked in between them

Now it you really want a sweet handling rig, I used to dive with a triple set of Russan titanium tanks. :14:

Ron

 

[WD8CDH]

By the way, although I prefer a standard set of double short aluminum 50s (6.9" diameter) over a single 100, it is no comparison to a set of skinny doubles.

Ron

 

[JerseyRick]

Go with twin 85's. Forget the triple idea - the previous poster is right - you may get a ton of laughs with triples - way too much hardware for an equivalent amount of air.

 

[Jimmer]

Go with twin 85's. Forget the triple idea - the previous poster is right - you may get a ton of laughs with triples - way too much hardware for an equivalent amount of air.

I think you're missing the point here. He doesn't want 170cf of gas, he wants 80 to 100, which is why he was asking about triple 30's or double 40's. I think double al40's or steel 45's are the way to go for you personally.

 

[Bob3]

Poseidon has a wonderful modular valve / manifold system, you buy individual parts & assemble as needed. They didn't go over all that well in the US so if you wanted to go that route you'd need to buy from the EU & with the worth of the US dollar being at historic lows things may get expensive to the tune of 50% more - closer to 60% against the Scandinavian currencies.
It sounds like you'd be a good candidate for an Interspiro (formerly AGA) rig.
I have a tiny set of AGA doubles that were made in the US by PST - 4400psi fills were unheard of though & still hard to find in a lot of places.

If you're still after a set of tanks that gives a modest capacity, go with a pair of 40 cu footers.
It's not just about drag, but trim & balance play a big part.

 

[WD8CDH]

Speaking of skinny tanks, has anybody seen tank boots for 4.9" or 5.25" diameter tanks?

Ron

 

[5ata]

So can anyone give a parts list for what would be needed to put together a setup like - I understand the tank end of things, but I also dive with Poseidon regs using DIN valves and want to dive that with the dual tanks.

I was at DEMA and this tech diving stuff is a little overwhelming to this minimalist freediver so any input sure would be appreciated.

My LDS has no clue about this kind of thing so I'm having to find out by asking questions here on SB.

Thanks

 

[captain]

The small tripples could be done but I don't believe there are any "off the shelf" parts to do it. I inspected one of Cousteau's rigs which was 4 small HP cylinders manifolded together with one cylinder held as a reserve. The plumbing would not that difficult to fabricate using several K valves, stainless steel tubing and fittings and some machine work. If I ever get my hands on three 40cuft cylinders I might give it a try. Two main cylinders and one reserve for 120 cuft total. There would be no isolation between the two main cylinders, only between the two mains and the one reserve with the reserve mounted inverted on the right side with the valve at my hip.

Here is a picture of the Cousteau rig.

 

[JohnW]

So can anyone give a parts list

I know your considering twins now, but here is some info on the triples that may or may not help.

Vintage Scuba Supply has a triple manifold from the USD Setup for $260. unfortuneatly it is Yoke, not Din.

Vintage Scuba Supply - New Arrivals

You would still need a set of bands, there are a few folks here on Scuba Board that can point you in the right direction on bands (Luis or Nemrod). I had triple bands made by Victor in Ontario Canada and can highly recomend him. The craftsmanship was superb.

The setup is alot of fun, well balanced and the trim is spot on. No ones laughed yet(well at least not to my face)