Mathematical model of wetsuit's buoyancy

Hi,
I am researching the mathematical model for the buoyancy of a wetsuit and I was wondering if anyone out there had already researched this subject.

More specifically I am trying to figure out how a wetsuit will change its buoyancy characteristics with depth.

On first approximation one could think that the model is linear (air trapped in the wetsuit get compressed proportionally to pressure at depth) ..... but .... it seems to me that, in addition to air, there are other materials in the wetsuit that might get compressed in a non linear way.

Any suggestion?

Thanks

AM

I would just look at the density of the N2 Bubbles in the suit. The rest of the material are all solids which cannot compress.

cudachaser:

I would just look at the density of the N2 Bubbles in the suit. The rest of the material are all solids which cannot compress.

Click to expand...

I_AM - why only N2 and not the other gases too?

Too many variables. Plastics lose elasticity and becomes more rigid with age, thus might compress less. Even within the same batch of neoprene, you might have areas of different densities. Each companies have their own formulation of neoprene, thus complicating matters more. Some neoprene are compressed, thus changes little with pressure.

Mathematical models would most likely rely on Boyles law (PV= constant) - direct relationship between pressure and volume - to be simple. In real life, it is likely non-linear. Second variable you have here is temperature. Not only does it affect the volume of gas, but it will change the elasticity of the neoprene also.

fisherdvm:

Too many variables....

Click to expand...

bah- shame on the naysayers! I think the OP should get some neoprene of various ages, thicknesses, and densities and then gather some empircal research. This would involve "weighing" the neoprene at different depths to see how the buoyancy changes. It would be a great excuse to go diving.
of course real divers don't need an excuse

Cause that's what they use for the bubbles

I_AM:

Hi,
I am researching the mathematical model for the buoyancy of a wetsuit and I was wondering if anyone out there had already researched this subject.

More specifically I am trying to figure out how a wetsuit will change its buoyancy characteristics with depth.

On first approximation one could think that the model is linear (air trapped in the wetsuit get compressed proportionally to pressure at depth) ..... but .... it seems to me that, in addition to air, there are other materials in the wetsuit that might get compressed in a non linear way.

Any suggestion?

Click to expand...

For what it's worth, I wrote an article on weighting which included:

"Data on neoprene foam compressibility seems hard to find, but the following table was derived from some data on insulation loss with depth:

Depth (ft) Reduction in Thickness (Percent)

20 20
40 35
60 50
100 70

My 1/4-inch wetsuit (which fit well when I weighed about 210 pounds) is made up of about 3000 square inches of closed-cell neoprene foam. That’s about 750 cubic inches of foam. It weighs about 9 pounds and would displace about 62.4(750/1728) =27 pounds of fresh water if uncompressed. Hence, on the surface, it’s about 18 pounds light. At 20 feet it would be about (27)(1.0-0.8)-9 = 12.5 pounds light; at 40 feet, about 8.5 pounds light; at 60 feet, about 4.5 pound light; and at 100 feet, about 1 pound heavy."

Another responder mentioned imponderables such as aging, etc. I once tried to chase down information about that, but came up empty. No surprise, since manufacturers of neoprene foam aren't about to advertise that sort of thing.

But the bubbles still use the same proven laws of physics

fisherdvm:

Too many variables. Plastics lose elasticity and becomes more rigid with age, thus might compress less. Even within the same batch of neoprene, you might have areas of different densities. Each companies have their own formulation of neoprene, thus complicating matters more. Some neoprene are compressed, thus changes little with pressure.

Mathematical models would most likely rely on Boyles law (PV= constant) - direct relationship between pressure and volume - to be simple. In real life, it is likely non-linear. Second variable you have here is temperature. Not only does it affect the volume of gas, but it will change the elasticity of the neoprene also.

Click to expand...

do it easy:

bah- shame on the naysayers! I think the OP should get some neoprene of various ages, thicknesses, and densities and then gather some empircal research. This would involve "weighing" the neoprene at different depths to see how the buoyancy changes. It would be a great excuse to go diving.
of course real divers don't need an excuse

Click to expand...

Yeh, and sew them into a "coat of many colours".... Dive with them, and see where your skin feel the coldest....

Better yet, do an infrared photo of yourself with the suit of many colors, and dive to different depths.... and take more IR photos.

Then post them on scubaboard!!! Then we'll really know which neoprene thickness at what depth worked the best...

fisherdvm:

Yeh, and sew them into a "coat of many colours".... Dive with them, and see where your skin feel the coldest....

Better yet, do an infrared photo of yourself with the suit of many colors, and dive to different depths.... and take more IR photos.

Then post them on scubaboard!!! Then we'll really know which neoprene thickness at what depth worked the best...

Click to expand...

I think that you are confusing buoyancy and insulation... the OP didn't ask anything about heat loss or IR photos

More specifically I am trying to figure out how a wetsuit will change its buoyancy characteristics with depth.

Click to expand...

cww