Making Steel Doubles as Buoyant as Possible

[Jiminy]

Swim them up from what depth? There are other factors involved

a diver who is wearing a 7 mm full wetsuit with attached hood who requires 22 pounds/10 kilograms of weight to be neutrally buoyant on the surface. If we assume that the wetsuit is providing the 22 pounds/10 kilograms of lift at the surface, then, at 130 feet/40 meters, the wetsuit will only provide 4.4 pounds/2 kilograms of lift (one fifth of the surface lift). This means that, ignoring all other factors, the diver will be 17.6 pounds/8 kilograms negatively buoyant at 130 feet/40 meters

The Ups and Downs of Buoyancy Control — DAN | Divers Alert Network — Medical Dive Article

 

[michael-fisch]

Not exactly right, neoprene is not just gas, it also has mass. Assuming that the neoprene is 22lbs buoyant at the surface, weighs 10lbs by itself and is made of the cheapest softest neoprene in existance it will only loose 4/5 of 12lbs at 40M of depth.

Michael

 

[swimlikethefish]

Double 85's are -13.4lbs full and 0 when empty. Just free flow your regs and empty the tanks (not fully as you still need to breath). You will gain close to 13.4 lbs of lift.

Or, get a lift bag and climb your way to the surface. Better start practicing that now if you plan on taking any tech courses. Every course I've done required a lift bag ascent.

 

[seeker242]

Is there any permanent, unobtrusive way to add buoyancy like some kind of air bladder in the space between the tanks which cannot be punctured?

No, not unless you jury rig some hackey abomination. I would not consider it wise to try and use a jury rig hack to save your life.

 

[Compressor]

Swim them up from what depth? There are other factors involved


The Ups and Downs of Buoyancy Control — DAN | Divers Alert Network — Medical Dive Article

The paper from DAN should be required reading for all divers. It is well written and at least for me is an eye opener.
Thankf for posting it.

 

[Doby45]

This does not seem wise and you basically keep asking the same question in different ways in different sections of the forum. You have already been given solid answers to your question of offsetting the added weight of steel doubles. Dual bladder wing, lift bag or drysuit. Anything other than those answers are outside the norms of traditional steel doubles diving.

PS. Anything other than the solutions mentioned above would not be acceptable in a class that revolves around doubles. Food for thought.

 

[ofg-1]

Back in ancient times, we would cut a length of PVC pipe, cap it, and strap it between the doubles. You may get 4 or 5 pounds out of it, depending on the diameter and length of the pipe. Do not use thinwall pipe.

 

[CaveSloth]

This does not seem wise and you basically keep asking the same question in different ways in different sections of the forum. You have already been given solid answers to your question of offsetting the added weight of steel doubles. Dual bladder wing, lift bag or drysuit. Anything other than those answers are outside the norms of traditional steel doubles diving.

PS. Anything other than the solutions mentioned above would not be acceptable in a class that revolves around doubles. Food for thought.

Well and apparently nothing but a drysuit is acceptable to the DIR / GUE crew.

 

[MaxBottomtime]

Or aluminum tanks with a wetsuit. You can always use the aluminum tanks later as deco bottles when you take your tech courses. It's so much easier than trying to reinvent the wheel by coming up with ad-hoc solutions.

 

[Storker]

apparently nothing but a drysuit is acceptable to the DIR / GUE crew

Well, it is hard to argue that a drysuit isn't the simplest, most efficient and most rational solution to your problem. And that's before we look at its fundamental task: to keep you warm and comfy in the water, with sufficient core heat left after the dive to completely avoid being cold during the SI.