What are your thoughts about our constant buoyancy BCD ?

[eelnoraa]

The diver determines if they are positive or negative and then adjusts the amount of air in the high pressure bladder. This is NOT an automatic servo-system.
It may best be described (as one of the commenters called it) as "variable static buoyancy."

I think Chris has it spot on. You have lack of understanding about buoyancy. The fact that driver needs a BC is because the overall buoyancy changes as the dive progress. Either by the change of weight of your gas, or exposure suit buoyancy change .... . Throughout the dive, the diver needs to determine his/her own buouyancy and adjust accordingly. In your system, it seem the diver still need to adjust his/her buoyancy, but this is not done once, but throughout entire dive, which effectively random your system useless. I think the assumption that once adjusted to neutral, the overall buoyancy doesn't change much throughout the dive is fundamentally incorrect.

 

[lmarks]

Next question: Does your system auto deflate upon ascent, as it auto inflates upon descent? Or is the lack of runaway ascents solely dictated by the small displacement of the bladders.

The system does not do anything "automatically." It is an "adjustable (by the diver) static bladder" Since it does not change volume with ascent, the diver remains neutral as he/she rises. Of course, they can add air as they approach the surface.

---------- Post added August 21st, 2014 at 06:27 AM ----------

How exactly do you detect and decide whether the diver is positive or negative buoyant? What external signal or measure do you use to detemine this?

The system does not attempt to determine positivity or negativity. That would probably be impossible to do for a number of sound technical reasons. With our system, the diver determines if they are positive or negative and then adds or subtracts air from the bladder accordingly.

---------- Post added August 21st, 2014 at 06:38 AM ----------

I think Chris has it spot on. You have lack of understanding about buoyancy. The fact that driver needs a BC is because the overall buoyancy changes as the dive progress. Either by the change of weight of your gas, or exposure suit buoyancy change .... . Throughout the dive, the diver needs to determine his/her own buouyancy and adjust accordingly. In your system, it seem the diver still need to adjust his/her buoyancy, but this is not done once, but throughout entire dive, which effectively random your system useless. I think the assumption that once adjusted to neutral, the overall buoyancy doesn't change much throughout the dive is fundamentally incorrect.

An experienced diver who is slightly negative at the start of a dive will usually not use their BCD at all during a dive. From an empirical standpoint, I can tell you that when I dive our BCD I do not make adjustments during the dive, but can control my buoyancy with breath control only.

 

[flots am]

The system does not do anything "automatically." It is an "adjustable (by the diver) static bladder" Since it does not change volume with ascent, the diver remains neutral as he/she rises. Of course, they can add air as they approach the surface.

I'm really confused by this.

Your statement: "Since it does not change volume with ascent, the diver remains neutral as he/she rises" doesn't seem to make any sense.

If your BC doesn't change volume on ascent, how is it different than diving with a sealed piece of PVC pipe, or even better, not being overweighted in the first place?

flots.

 

[yardpro]

i would not buy it because there are times when I want to be very heavy in the water... ie, installing mooring, working on something on the boat, etc...

 

[Bob DBF]

I obviously need to do a better job explaining the device. It offers "variable static buoyancy" that is you actively set your buoyancy - positive, neutral, negative - your choice - and then it is fixed - you have to do little or no further adjustment during the rest of the dive. I hope this is a better explanation.

OK, explain it in my case, I already weight properly for my dive, I'm on the bottom @ 110' with a steel 120 and a 7mm Farmer John wetsuit. I set your device to make myself neutral. Two questions, how do I adjust for the 7# of air used on my dive, how do I adjust for the 15+# of buoyancy gained from the wetsuit as I surface. Using your device as described will have me over 20# buoyant as I ascend through my safety stop, not something I haven't done, but something I do not enjoy doing.

I started diving before the BC and have a reasonable understanding of weighting and buoyancy, please let me know how this device will work to enhance my diving.




Bob
------------------------------
Always use the right tool for the job. A hammer is the right tool for any job. Anything can be used as a hammer.

 

[Diver0001]

We have developed a BCD that does not change buoyancy with depth. This prevents runaway ascents and descents. With it you do not have to inflate and deflate the BCD during a dive. It allows the diver to precisely compensate for overweighting and the compensation is fixed regardless of depth. Details are at Home. We have not yet commercialized this technology and would like to get feedback from divers before doing so. Do you think this would be a useful feature ? Are there disadvantages we may not have thought of ?

Disadvantages ... maybe not.

but factually anyone who can dive doesn't need this.

You have created a solution for a problem that does not exist.

R..

 

[tursiops]

OK, explain it in my case, I already weight properly for my dive, I'm on the bottom @ 110' with a steel 120 and a 7mm Farmer John wetsuit. I set your device to make myself neutral. Two questions, how do I adjust for the 7# of air used on my dive, how do I adjust for the 15+# of buoyancy gained from the wetsuit as I surface. Using your device as described will have me over 20# buoyant as I ascend through my safety stop, not something I haven't done, but something I do not enjoy doing.

I started diving before the BC and have a reasonable understanding of weighting and buoyancy, please let me know how this device will work to enhance my diving.




Bob
------------------------------
Always use the right tool for the job. A hammer is the right tool for any job. Anything can be used as a hammer.

His previous answers to this are that you use your lungs to counteract the gas used from the tank, and your wetsuit does not lose any buoyancy as you dive.
He is either lying or really really confused. I'll give him the latter.

 

[Lost down under]

I haven't been this confused since someone told me the story of Schrodinger's cat.

If you can't explain a product to a bunch of enthusiastic diver on here how are you going to market it?

 

[DaleC]

I think what he is saying is that he has very strong/thick/resistive bladders that require high pressure to inflate and, because of this, will not over inflate on ascent (the resistance of the bladder being able to overcome the force of expansion) - thus preventing runaway ascents. I hope I got that right.

But I think the outward pressure that would be exerted by gas expanding to 4 atm's without venting might require significant engineering. Take a coke bottle down to 100', fill it with air, cap it and watch what happens when you take it to the surface.

 

[flots am]

I think what he is saying is that he has very strong/thick/resistive bladders that require high pressure to inflate and, because of this, will not over inflate on ascent (the resistance of the bladder being able to overcome the force of expansion) - thus preventing runaway ascents. I hope I got that right.

It still doesn't make any sense. How is this different from diving with a 1' section of PVC pipe with endcaps glued on each end?

All I have so far is that if you become negative when you descend, this thing fixes it somehow, and then doesn't change buoyancy, even though your wetsuit will and your tank will, but somehow you're still neutral.

It's either smoke and mirrors or the OP needs to figure out how to explain it better.