Buoyancy Characteristics Info

[ScubaFeenD]

I know I have seen some charts of buoyancy characteristics for various equipment. Specifically I am referring to dry suits, undergarments, and wetsuits, and what their individual addition to buoyancy (in pounds neg or pos) would be.

I would have searched this but dont know how to really focus my search to prevent hours of sifting through every thread about buoyancy.

Thanks to anyone that can help.

 

[Afishianado]

I would love to find a good chart like this. I have heard people talking about their rules of thumb, etc how much to account for this or that but when I thought about the answers they didn't make any sense. I have resigned myself to the fact that I will have to develop one of my own by actually talking gear into the water and weighting the pieces individually to measure the buoyancy of each piece..

 

[cool_hardware52]

The charts don't exist. Even wetsuit manufacturers do not / cannot provide this information.

Drysuits? Really? The buoyancy of a drysuit is dependent on the undies used and the fit of the suit. There's only an infinite number of possible combinations.

Sorry there's no short cut to testing your own set up.

Tobin

 

[Chris12day]

Everyone always tells me I carry too much weight. I am 5'6" and weigh just under 160 pounds. I carry an 80 cuft aluminum tank. In salt water with no air in my BCD to control my buoyancy, once I have left the surface.

3/2 mil wet suit -- 18 ponds (tropics)
7 mil wet suit -- 22 pounds (cold water 50F)

On every boat they tell me they can reduce my weight while in the boat. When I fail to drop, they always give me more weight.

I just finished my pool session for dry-suit cert. We first went through the 10% plus 4 pounds (10 pounds BCD release pockets and 10 pound weight belt). The full tank was a 63 cuft aluminum. Emptied dry suit, I now know what a squeeze feels like, exhale my lungs...I float. Added two pounds....then another two pounds. I could sink initially, but had to fight to stay under. I also could not add any air to my dry suit for the squeeze. Ended up carrying 26 pounds total (additional six pounds added to my weight pockets next to my tank) and was comfortable in the pool water completing the necessary exercises.

I was not wearing any gloves or hood in the chlorinated pool dive.

Long story short review...Check YOUR own buoyancy for YOUR set-up. Use the amount of weight YOU personally need to safely descend, control buoyancy on the bottom, ascend, and complete YOUR safety stop(s).

Safe diving

 

[dave4868]

I would love to find a good chart like this. I have heard people talking about their rules of thumb, etc how much to account for this or that but when I thought about the answers they didn't make any sense. I have resigned myself to the fact that I will have to develop one of my own by actually talking gear into the water and weighting the pieces individually to measure the buoyancy of each piece..

You're right. Measuring the buoyancy of each piece of gear will be the most accurate. It won't take long to create your personal list, will it?

I have a "rule of thumb" for estimating weight required for drysuit undergarments that I sometimes mix and match. I simply estimate the volume of water the undergarment will displace. If I want to add a chest pad, I'll fold it up, compress it slightly, estimate its displacement and required weight (8 lbs per gallon).

It's going to be close enough because I prefer to wear about 10% more than the "minimum" or "perfect" weighting anyway. I have some room for error.... For those who want to achieve what is generally considered ideal weighting, this probably won't be satisfactory....

Dave C

 

[cool_hardware52]

Everyone always tells me I carry too much weight. I am 5'6" and weigh just under 160 pounds. I carry an 80 cuft aluminum tank. In salt water with no air in my BCD to control my buoyancy, once I have left the surface.

3/2 mil wet suit -- 18 ponds (tropics)
7 mil wet suit -- 22 pounds (cold water 50F)

The typical 3mm full suit is 3-6 lbs positive and the typical 7mm suit is 18-22 lbs positive.

If you only need 4 lbs more in a 7mm suit, and the rest of gear is the same, something is wacky.

Tobin

 

[Chris12day]

Just call me wacky....

Same gear: gloves, hood, 19cft pony, camera w/strobe, and SMB.

Safe diving

 

[FL-Jack]

Everyone always tells me I carry too much weight. I am 5'6" and weigh just under 160 pounds. I carry an 80 cuft aluminum tank. In salt water with no air in my BCD to control my buoyancy, once I have left the surface.

3/2 mil wet suit -- 18 ponds (tropics)
7 mil wet suit -- 22 pounds (cold water 50F)

I am a sinker. With no wetsuit and an 80cu I do not use lead. 5lb with my full 3mil and hood.

As a matter of fact I have a difficult time even floating in the ocean. Forget the pool!

 

[The Kraken]

Charts for neoprene products would be very problematic at best.

Neoprene is produced in lots. Although manufactureres try to keep the properties of varying lots as close to a median as possible, there are still variations within the individual run, not to mention different product runs.

Add to that the fact the the manufacturers of wet suits, etc., probably shop among different neoprene manufacturers for the best pricing adds another variable to the formula.

For a wet suit manufactuer to state that "X" wet suit is "Y" pounds buoyant they would have to be certain that each individual lot of neoprene exhibited the exact same buoyancy properties.

If they were to do this and someone were injured in some manner that could be associated with the wet suit she or he was wearing, then the manufacturer would be in a position of liability because of the published statement of buoyancy.

I'm sure you can see where all of this goes.

Consider, too, the all wet suits lose buoyancy over time due to repetitive compression and expansion breaking down the cellular structure.

the K

 

[ScubaFeenD]

The charts don't exist. Even wetsuit manufacturers do not / cannot provide this information.

Drysuits? Really? The buoyancy of a drysuit is dependent on the undies used and the fit of the suit. There's only an infinite number of possible combinations.

Sorry there's no short cut to testing your own set up.

Tobin

I dont think this is totally unreasonable. Surely there must be a range of buoyancy figures that can generally work. If they dont exist then I accept that, but I would think people would generally be happy with having an IDEA of where they should start their weighting. Clearly a chart would only be a starting point and not something to base your final weighting on--im not sure why everyone here thought I was going to calculate on paper and be done with it.