Baby doubles (steel, ~ 55 cf)?

[Jimmer]

For those of you curious, this is how a set of 72's and 45's compare in height. Personally I dont feel any significant trim change that cant be accomodated for by adjusting my feet slightly.

 

[rx7diver]

Here is another photo comparison. (I had actually intended to assemble all this stuff, but, after locating all the bits, dragging it up from the basement, dusting the spiderwebs off of the OMS LP 45's, and transferring the valves from the Al 80's to the 45's, I ran out of steam!)

Anyway, for sake of comparing relative sizes when considering (baby) doubles, here are, from left to right: (1) PST HP 80's (my first doubles, worn only briefly c. 1988 while diving wet), (2) the OMS LP 45's, (3) Luxfer Al 40's (these replaced the 45's as my deco bottles), (4) Al 80's (these I wear as independent doubles when solo diving dry), and (5) PST HP 120's (my extended range tanks, now worn as independent doubles; these 28-inch tanks replaced my exquisite HP 100's because I had difficulty reaching my valves when wearing the four-inch-shorter 100's).

The length, weight, and buoyancy of these tanks can be found on the Techdiving Limited Web site and elsewhere on the Web.

Hope this is useful.

 

[rx7diver]

... I keep thinking that if I could find a used pair of the old Scubapro "Slim-line" 3300 psig 72's (sold in the late 1980's, if memory serves, at the same time Scubapro sold the shorter "Slim-line" 63), I might be able to double them up with this old hardware and have a nifty set of practical "baby doubles."

When looking for bits for the photos in my previous post in this thread, I found my old Scubapro catalogs in a long-unopened box in my garage. My oldest, from 1986, advertises the "New! Scubapro 71.4 cubic ft. 'Slim-Tank'." The 1987 catalog advertises both the 71.4 cu ft Slim-Tank and the 60.6 [sic] cu ft Slim-Tank. These catalogs were from an era when much more technical info (and less glitz) appeared on the pages of Scubapro catalogs.

The 71.4 had a 6.00" diameter, a 25.39" length, an empty weight of 26.0# without valve, a working pressure of 3300 psig (= 3000 + 10%), and a salt water buoyancy of -2.25# empty.

The 60.6 had a 6.00" diameter, a 22.00" length, an empty weight of 22.7# without valve, a working pressure of 3300 psig, and a salt water buoyancy of -2.5# empty.

I believe Faber manufactured Scubapro tanks at that time.

My registration for the Faber Web site finally went through, and so I was able to learn a bit more about Faber's current offerings. Faber currently manufactures the following two DOT- and TC- certified tanks:

A 550 cu in water capacity tank, which has a 6" diameter, a 25.39# length, an empty weight of 26#, and a working pressure of 3300 psig (= 3000 + 10%). No buoyancy is given. I calculate this tank's capacity to be 71.45 cu ft.

A 464 cu in water capacity tank, which has a 6" diameter, a 22.05# length, an empty weight of 23#, and a working pressure of 3300 psig (= 3000 + 10%). No buoyancy is given. I calculate this tank's capacity to be 60.28 cu ft.

These two currently produced Faber tanks seem to be (essentially) the old Scubapro Slim tanks!! (The Scubapro 60.6 disappeared from the Scubapro catalog beginning in 1993. And neither the 60.6 nor the 71.4 appear in the 1996 and later Scubapro catalogs. [I don't have the 1995 catalog.])

So here's the upshot of all this: I believe a pair of these Faber 550's would make a delightful set of "baby doubles." (In fact, for him who doesn't require as much length in his tanks, these Faber 464's would work superbly, I think!) At 4000 psig, the 550 doubles would hold an indicated 173 cu ft (= 2 x 86.5)—not that I would ever suggest or condone the extremely dangerous practice of overfilling these DOT 3AA Chrome-Moly plate steel tanks which have a test pressure of 5000 psig.

NOTE: These 550 doubles (and 464 doubles) probably should NOT be worn in open water by wet suit divers, perhaps, if in fact these tanks have the same buoyancy characteristics as the old Scubapro Slim-Tanks.

 

[JS1scuba]

Baby doubles are not a new idea. The folks over in Europe have been doing it for years. Some use what are called dumpy tanks short fat tanks, others use slimmer tanks. Here in the states the most popular albiet rarely used small doubles were the Faber LP 45s with a straight manifold. OMS first introduced them in 1994 and they became a popular set up for divers who wanted to keep thier doubles regs and plate and just do a little dive. I have a few sets of these and my wife likes to use them now and then for little dives.

In 2000 or so Faber began distribution directly and you could get the Faber 45s and Faber 50s and double them up. The original Highland Millworks (not XS) made up 5.5" bands and they worked well with the Thermo brand manifold with short centepiece. Today Dive Rite is the only maker of a 5.5" band set that I know of.

There is zero reason for an isolator on these tanks as they only hold about 100 cuft of gas which would not really be used in anything other than no stop dives.

But here comes the big rub with using these. COST ... by the time you are done with 2 LP 45s bands and manifold you are pushing $900 a set. (new) At that point what's the point? You may just be better off buying a small wing, and some H-valves for some singles. The end result would be the same. 100 cuft using your doubles regulator set up.

Sure the profile is smaller and more compact but unless you plan to use these tanks all the time I think they may just fulfill a novelty.

My 2 cents.

Cheers

 

[Jimmer]

I agree Joel with pretty much everything you said there. The reason I have an isolator on mine is quite simple. I didn't want to purchase a dedicated manifold for them, incase I didn't like them I could use the standard manifold for something else. On top of that, I paid something like $110 for the pair of 45's, again I agree if I was buying new I wouldn't in a million years have bought them for doubles.

 

[rx7diver]

Joel, can you guess a street price for the Faber 550 I described in my post above?

 

[rx7diver]

Jimmer, were the tank bands that Victor (detroit mudpuppy) made for your baby doubles, custom made? If so, was it expensive to commission them? I seem to remember that when I purchased my off-the-shelf, non-isolating manifold bar for my OMS 45's (c. 1996), one could special order custom made bands from OMS and other manufacturers of tech diving equipment. I don't think I ever learned the price for this special service, though.

(Sorry, I just got mixed up and posted this on your earlier "baby doubles" thread.)

 

[Jimmer]

Jimmer, were the tank bands that Victor (detroit mudpuppy) made for your baby doubles, custom made? If so, was it expensive to commission them? I seem to remember that when I purchased my off-the-shelf, non-isolating manifold bar for my OMS 45's (c. 1996), one could special order custom made bands from OMS and other manufacturers of tech diving equipment. I don't think I ever learned the price for this special service, though.

(Sorry, I just got mixed up and posted this on your earlier "baby doubles" thread.)

They weren't custom, they are an "off the shelf" item from him, that allows you to use the 5.5" tanks with a standard manifold. If you PM him or search for his ebay store, I think it's called Technical Solutions, you can get a price that way.

 

[JS1scuba]

Joel, can you guess a street price for the Faber 550 I described in my post above?

I would assume $350 per cylinder