I'd love to see it too (just the "enginerd" in me). My suspicion is that they were vented/open bottom, with a internal bladder that is connected to a "typical" inflator.
Wing made from PVC pipe.
- Thread starter Rich Keller
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Thanks!
Very interesting - not even as complex as I envisioned - no bladder - so much for horizontal trim or a slight heads down position as they will empty... reminds me of a garbage can as a lift bag...
Very interesting - not even as complex as I envisioned - no bladder - so much for horizontal trim or a slight heads down position as they will empty... reminds me of a garbage can as a lift bag...
That probably explains why I never saw one at the beach or LDS. 
However, it “might” have helped inspire the first BCs and wing. This was a time when the Bouée Fenzy horse collar emergency floatation vest was the first that could be inflated at depth from a very small onboard HP cylinder. There wasn’t enough gas onboard to waste on buoyancy compensation and still be sure enough would be left if you actually needed it. Some years later guys added power inflator valves from early drysuits and discovered what a BC was good for.
The Fenzy cost an eye-watering at $125 and mostly professional photographers used them in the US at that time.
However, it “might” have helped inspire the first BCs and wing. This was a time when the Bouée Fenzy horse collar emergency floatation vest was the first that could be inflated at depth from a very small onboard HP cylinder. There wasn’t enough gas onboard to waste on buoyancy compensation and still be sure enough would be left if you actually needed it. Some years later guys added power inflator valves from early drysuits and discovered what a BC was good for.
The Fenzy cost an eye-watering at $125 and mostly professional photographers used them in the US at that time.
nice information, thanks
Dacor had the Nautilus rigid ballast system in the late 70's. I you do a quick search you will find more information.
I own one of the Dacor Nautilus (I need to service the valves and inflator). I have dove a different Nautilus and it is interesting. The major draw back is the size. It has a huge lift capacity that is not needed.
White Stag also has a smaller rigid ballast system, but I have only seen pictures of it.
Thanks for the information on the Saf-T-Ballast.
I have been wanting to make something that looks similar out of PVC, but with a simple plugs on the bottom of each cylinder. I would only pull the plugs at the end of a dive to flood the cylinder. At that point my tank is lighter and my wet-suit is going expand again as I approach a safety stop depth. If I am properly weighted all I need is about 10 LB of ballast cylinder. That would be two fairly small tubes. One of this days, when I have time I will try it.
I own one of the Dacor Nautilus (I need to service the valves and inflator). I have dove a different Nautilus and it is interesting. The major draw back is the size. It has a huge lift capacity that is not needed.
White Stag also has a smaller rigid ballast system, but I have only seen pictures of it.
Thanks for the information on the Saf-T-Ballast.
I have been wanting to make something that looks similar out of PVC, but with a simple plugs on the bottom of each cylinder. I would only pull the plugs at the end of a dive to flood the cylinder. At that point my tank is lighter and my wet-suit is going expand again as I approach a safety stop depth. If I am properly weighted all I need is about 10 LB of ballast cylinder. That would be two fairly small tubes. One of this days, when I have time I will try it.
The Imperial Turtle back pack of the mid 70ies had a similar design philosophy. It was a hollow, rigid back pack where one could introduce or remove air. Unfortunately, the bottom was open and would vent air when the diver made a head first descent-I think it was this "feature" was its undoing.
Great (or at least DIY) minds think alike. I too have toyed with the idea of using PVC pipe for temporary counter ballast. I.g. at the beginning of a dive with my steel 100 and SS backplate I am just a tad over weighted with the amount (little to none) of thermal protection I most often use. An empty, sealed section or two of PVC pipe that I could flood when the tank had less pressure/weight seems like a reasonable idea.
Getting back to the OP's question. Why not employ an accordion type bag inside the PVC pipes? That would solve the issue that the White Stag and Turtle design had.
Great (or at least DIY) minds think alike. I too have toyed with the idea of using PVC pipe for temporary counter ballast. I.g. at the beginning of a dive with my steel 100 and SS backplate I am just a tad over weighted with the amount (little to none) of thermal protection I most often use. An empty, sealed section or two of PVC pipe that I could flood when the tank had less pressure/weight seems like a reasonable idea.
Getting back to the OP's question. Why not employ an accordion type bag inside the PVC pipes? That would solve the issue that the White Stag and Turtle design had.
OP
Rich Keller
Contributor
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? The first thing that came to mind using PVC tubes would be an air intake at the top and a vent at the bottom of both tubes. Purge valves at the bottom was their solution but this was meant more for a heads up assent. What is needed at the bottom are valves that will open only when the inflator buttons are being used. The only other way I can think of would be to run a hose from the bottom of the tube on the divers left to the tube on the right and then from the right tube to a 1/4 valve on the divers right side. This would require a 2 handed approach in the slightly heads up position in order to use it. Open the 1/4 turn valve first with your right hand, add or dump air with a normal inflator in your left hand then when you are done close the 1/4 turn valve. If you make this out of the heavier schedule 80 PVC instead of the more common white PVC the tubes should be able to handle more stress from increasing pressure during assent but I have no idea if the joints on the 80 would be any stronger then the regular PVC joint would be.
GrumpyOldGuy
Contributor
I had a friend who had a Nautilus to play with (I never dived it). He claimed since it was rigid, the volume did not change with dept making buoyancy control a little easier. The logic involved was you only need to tweak for suit compression rather than suit + badder. The unit as bulky though.
halocline
Contributor
They talk about 'steady' ascent rate, which implies to me that the bubble does not increase in size as the diver ascends; this would be the advantage of a rigid system I suppose. But if the bottoms are open, unless the cylinders are completely filled with air the bubble's going to expand. It's kind of like using a bucket as a BC.
Anyhow, thanks to Akimbo for posting those interesting articles. It's nice to see that they were using girls in bikinis and questionable 'scientific' claims to sell dive gear even back then!
Anyhow, thanks to Akimbo for posting those interesting articles. It's nice to see that they were using girls in bikinis and questionable 'scientific' claims to sell dive gear even back then!
