Wing made from PVC pipe.

[Sam Miller III]

There was a product in the late 1960s that used rigid plastic tubes that may provide some inspiration. I have a review from Skin Diver Magazine that I can scan into a pdf file if you want it.

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Akimbo Thank you!

I was ready to go to my SDMs and Catalogs for this one..you beat me to it!

The "saf T ballast" was early in the market place and had a very short life.

Certainly verifies that much of the short history of recreational diving has been ignored or lost and now the current crop is redesigning the wheel----over and over again and again---but they are thinking wet!

SDM

 

[Akimbo]

The Saf-T-Ballast tubes looked like they could provide a lot more then just the 13lbs of lift stated in the article. Could they have meant 13lbs for each tube?...

Thirteen pounds total sounds about right. Just guessing at dimensions, but let’s say each tube is 3" ID x 24". That is 169.6 In³ or 0.098 Ft³, so that is about 6.3 Lbs of displacement in sea water per tube.

I never used the Saf-T-Ballast or Nautilus, but have a lot of experience with rigid ballast tanks. Open bottom tanks are fine in a submarine or submersible for gross surface buoyancy, but are fraught with problems for divers that see dramatic shifts in orientation relative to vertical.

Rigid tanks have the advantage of constant buoyancy, but water sloshing around in them plays havoc with trim. They also have to be pressure-rated internal and external — implosion and explosion is really bad form.

Short of positioning a spherical tank at your center mass, it’s hard to imagine an elegant solution.

---------- Post added January 14th, 2013 at 09:00 AM ----------

Sam: It was just a strange coincidence that I was re-reading an old article on the Andrea Doria in that same issue of Skin Diver the night before and noticed the review. There is no way I could have responded so fast otherwise.

Can you find a review on the Dacor Nautilus? I’m not sure they did one… just guessing. You never know what can be learned or what ideas can be sparked in a literature review with an eye toward engineering.

It really is a shame that Skin Diver Magazines are not available online as a resource. Collectively it is certainly the best insight into recreational diving development in existence. I “have heard” that the “Skin Diver” name was purchased by a competitor, but not the content or copyrights.

 

[Rich Keller]

My impression from the article was they were bigger but there is no way to know for sure.

 

[Akimbo]

They may look bigger if you mentally compare them to a 7¼" OD cylinder that dominates today but, that is a 6.9" OD steel 72 in the picture. It doesn’t sound like much but they look much smaller to me.

Looking at the picture again, they must be larger in diameter than 3" because they are nowhere near 24" long. Either way, I can't imagine getting much more than 7 Lbs/tube out of the deal.

 

[Luis H]

The Nautilus system did not use a pressure vessel for ballast tanks. Instead it had a pressure regulator and pressure relieve valves to compensate for pressure changes. The trick was to adjust the ratio of air and water (in a somewhat vertical attitude) and close the bottom valve. When you are heading up the excess air vents from the slightly higher pressure relieve valve. You don't actually have to be in a vertical position at that point (you just can't be in a feet up position).

If you do a search in this board I think you will find copies of some instruction manual and/or reviews plus descriptions from Skin Diver magazine.

 

[East West]

I also was toying with this application for hauling heavy and bulky loads . It is a wonder that nobody has designed a independent rigid flotation ballast system for equipment intensive diving . A lightweight two compartment pressurized tank would do the trick .

 

[mddolson]

I was looking for ideas on making a light travel BP/W for a single tank and someone suggested making the wing out of an 8" PVC pipe. I was wondering if anyone here as done this? If I am understanding this suggestion right it would involve two 8" sections cut to the length of the backpack with a cross section at the top to connect both pipes. If you added caps at the bottom of the pipes you could also us it to store small items you do not want damaged in transit. If the basic premise works then how can you inflate and deflate this type of wing? My original idea involved attaching either Oxyquen 18lb, DSS 12 or 17lb wing to a commercial diving harness like this. The original problem I wanted to solve was finding a way to attach the wing other then along the center line of the harness.

View attachment 144716

Nice looking back plate btw:
I'm working on a similar idea, for air-travel (light weight) but also want some flexibililty.
I want to to dive singles with my (DR) rec-wing, & also be capable of side mount rigging for cenote diving.
It will be used as a traditional backplate, & wing with aluminum STA in O/W.
I'm planning on using 0.10 thick carbon composite. The top will be half round, rather than flat like traditional back plate.
The plate/wing positions are swapped for side mount & restraining straps are added to wing, attached to front waist D-rings to prevent taco-ing, & under arm bungies added for tank retention.
The two cam straps serve to hold lower tank bolt snaps.

Mike D

 

[cbrich]

There was a product in the late 1960s that used rigid plastic tubes that may provide some inspiration. I have a review from Skin Diver Magazine that I can scan into a pdf file if you want it.

That thing needs a toy space shuttle strapped to it; then it will complete the look.

 

[mddolson]

Any one remember the Watergill At-Pack?
It was probaly one of the first integrated weight & buoyancy systems.
Wing was similar to current B/P wing designs of today. But had optional hard shell to protect it from corral abration.
Scuba-pro also had a version.
Weight was via lead shot & marbles (to prevent rattle) in the pack, with bottom release trap door to dump wieight.
The weight system was flawed however, becasue the lead shot became encrusted with salt crystals & would not release.
Most used them with a standard weight belt after reports of failures.


Mike D

 

[Couv]

Mike D,

Have a look at this thread: http://www.scubaboard.com/forums/regulators/212330-seapro-regulators-atpak-bcd-units.html