I'll PM you my address. Send me one, and I'll let you know how it works 
What are your thoughts about our constant buoyancy BCD ?
- Thread starter lmarks
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
I understand your concept, but disagree with your solution. You "fix" the problem of an over-weighted diver. Good, but with many down-sides. One could also remove the extra weight. Much better, with no down-side.
You argue that buoyancy loss from wetsuit compression is negligible; that is just plain wrong. You say you tested this (for a 3mm from 40 feet); your tests were inadequate.
I'm a mechanical engineer; I'm impressed by your design.
But I'm a diver and instructor; your design is useless.
By analogy; you correct for overweighting. What would your design solution be for a recreational diver who is cold? A battery-powered, hot-water heater with tubes running through it? Or a thicker wetsuit? The former is one solution, the latter is the better solution. KISS.
You argue that buoyancy loss from wetsuit compression is negligible; that is just plain wrong. You say you tested this (for a 3mm from 40 feet); your tests were inadequate.
I'm a mechanical engineer; I'm impressed by your design.
But I'm a diver and instructor; your design is useless.
By analogy; you correct for overweighting. What would your design solution be for a recreational diver who is cold? A battery-powered, hot-water heater with tubes running through it? Or a thicker wetsuit? The former is one solution, the latter is the better solution. KISS.
More simple is better: cheaper to make, cheaper to maintain, more reliable.
Bouyancy is not a problem, it's a skill that needs to be practised and developed. Take away the responsiveness of a diver's gear to ineffective bouyancy control and you are damaging and disrupting the feedback he needs both to get his bouyancy right at that moment and also to learn how to better gain & maintain bouyancy control as a skill for the long term. In short, you are NOT doing him a favor.
Bouyancy is not a problem, it's a skill that needs to be practised and developed. Take away the responsiveness of a diver's gear to ineffective bouyancy control and you are damaging and disrupting the feedback he needs both to get his bouyancy right at that moment and also to learn how to better gain & maintain bouyancy control as a skill for the long term. In short, you are NOT doing him a favor.
I find it interesting you have spent 5 years developing a product that divers will not want and ask now what divers think of it, when that should have been done much earlier. It solves a problem that has an easier solution, it's more complicated, has a smaller range of use and will never be competitive in terms of prices. I don't see a future for it.
DaleC
Contributor
I'd like to see an actual picture of the BCD. From the website:
"Diving the ABCD is a dream. It has been described as "feeling like you are suspended on strings" as there are no forces pushing the diver up or down the water column."
A real product or a bogus claim?
Like Redshift, I just find it hard to believe a diver would invest 5 years in developing such a product, knowing what little benefit it would offer, or that a non diver would proceed that far down the rabbit hole without first polling the target consumer. It looks like one of those theoretical products marketing students have to create for a project.
The one basic question pertaining to this whole discussion is: Do the rigid containers shielding the bladders allow water to move in and out of them, or are they sealed? That answer will explain everything about the system.
If the answer is: They allow water to move in and out. Then this is just a submarine ballast system with small bladders within the ballast tanks. Add air to the tanks and they displace water. The displacement of water by lighter air creates buoyancy. The claims of limited runaway lift are just a result of using 4 small bladders. Add larger bladders and one would broach like the Squalus. My corresponding question would then be why not just use a smaller traditional BCD.
If the answer is: They do not allow water to move in and out. The whole concept is flawed. A rigid vessel does not change buoyancy characteristics when air is added, no matter how high pressure the air is within it. As Captain pointed out, the air is coming from somewhere already on the person so there is no gain/loss of weight.
"Diving the ABCD is a dream. It has been described as "feeling like you are suspended on strings" as there are no forces pushing the diver up or down the water column."
A real product or a bogus claim?
Like Redshift, I just find it hard to believe a diver would invest 5 years in developing such a product, knowing what little benefit it would offer, or that a non diver would proceed that far down the rabbit hole without first polling the target consumer. It looks like one of those theoretical products marketing students have to create for a project.
The one basic question pertaining to this whole discussion is: Do the rigid containers shielding the bladders allow water to move in and out of them, or are they sealed? That answer will explain everything about the system.
If the answer is: They allow water to move in and out. Then this is just a submarine ballast system with small bladders within the ballast tanks. Add air to the tanks and they displace water. The displacement of water by lighter air creates buoyancy. The claims of limited runaway lift are just a result of using 4 small bladders. Add larger bladders and one would broach like the Squalus. My corresponding question would then be why not just use a smaller traditional BCD.
If the answer is: They do not allow water to move in and out. The whole concept is flawed. A rigid vessel does not change buoyancy characteristics when air is added, no matter how high pressure the air is within it. As Captain pointed out, the air is coming from somewhere already on the person so there is no gain/loss of weight.
Last edited:
CAPTAIN SINBAD
Contributor
There are times when I want to be negative and there are times when I want to be positive during my dive. Static buoyancy will be a problem for me more than a solution. Just my 2 cents.
I believe this worked by having a rigid container which partially filled with water to vary buoyancy (like the ballast tank on a submarine). This approach results in a large heavy BCD and is difficult to adjust because the air bubble in the rigid container shifts about.
---------- Post added August 18th, 2014 at 07:00 AM ----------
Thanks for your comments.
---------- Post added August 18th, 2014 at 07:04 AM ----------
Thanks for your comments. You are one poster that clearly understands the technology. It is difficult for me to convey the experience of diving it. I would describe it as sort of feeling as if you are suspended by strings, like a puppet. I'm a very experienced diver and find that diving this BCD is a dream.
---------- Post added August 18th, 2014 at 07:07 AM ----------
You're right - When wearing thick neoprene, you must make adjustments during the dive --- but much less so than with a conventional BCD. Venting is well controlled and, in fact, one of the advantages of this type of system is that you can vent from any body position - you don't have to position the air bubble toward the venting port.
---------- Post added August 18th, 2014 at 07:10 AM ----------
We are looking for a partner with an established marketing presence. There is a legitimate concern that the costs associated with this feature might be a deterrent. It would probably retail in the $400 rqnge.
---------- Post added August 18th, 2014 at 07:12 AM ----------
There is a separate low pressure manual inflator.
---------- Post added August 18th, 2014 at 07:21 AM ----------
Thanks for your thoughtful comments. Answering your questions: 1-The primary mode of failure would be a bladder rupture. The bladder has withstood 2000 inflation-deflation cycles on the test bench but that does not insure with certainty that it could not occur. Therefore, the device is designed so that if one bladder ruptures, it is sealed off from the other three. 2-There is a redundant conventional bladder that can be inflated orally. 3-Maximum lift in the prototype is 16 lbs. This would be increased in a production model. The conventional bladder can be expanded for additional lift at the surface. 4-The high pressure venting is not a problem as the venting is through a restrictive orifice. It is actually more controllable than a conventional BCD. Furthermore, venting can be accomplished from any body position.
---------- Post added August 18th, 2014 at 07:23 AM ----------
Although attempts have been made to achieve constant buoyancy with an automatic mechanism, this is not one of them. There is no automation. The bladder simply has different inflation characteristics than a conventional BCD.
---------- Post added August 18th, 2014 at 07:27 AM ----------
With 3 bladders, there is still less "roll" than that experience when shifting body position with a conventional BCD. If 25 % or more lift capacity were lost, and was insufficient to maintain neutral buoyancy, the diver can use an incorporated redundant low pressure bladder system.
---------- Post added August 18th, 2014 at 07:28 AM ----------
Let me clarify. This is not a fixed volume container. It is a high pressure bladder whose volume can be adjusted.
---------- Post added August 18th, 2014 at 07:31 AM ----------
You are right. With a very thick wetsuit, the volume in the bladder must be adjusted during the dive -- just much less so than with a conventional BCD.
---------- Post added August 18th, 2014 at 07:33 AM ----------
This is not a rigid container, It is a high pressure bladder that has an adjustable volume.
---------- Post added August 18th, 2014 at 07:42 AM ----------
Good points. My responses: First of all our system does not have just one "fixed buoyancy". The buoyancy is adjustable, just not affected by depth changes. For the novice, this prevents runaway ascents (and descents). For the more experienced diver --- haven't you ever changed your rig so that your buoyancy is unknown- Then you hit the water and either need to add weight, or add a relatively large amount of air to your bladder to compensate for overweighting. That large amount of air is subject to considerable expansion and contraction during the dive, so you have to make frequent adjustments. If you don't experience either of these scenarios, then you would not derive much benefit from our system.
---------- Post added August 18th, 2014 at 07:48 AM ----------
This system does not have a rigid bladder. It has a high pressure bladder that has adjustable volume but does not change volume significantly with changes in depth.
---------- Post added August 18th, 2014 at 07:00 AM ----------
Thanks for your comments.
---------- Post added August 18th, 2014 at 07:04 AM ----------
Thanks for your comments. You are one poster that clearly understands the technology. It is difficult for me to convey the experience of diving it. I would describe it as sort of feeling as if you are suspended by strings, like a puppet. I'm a very experienced diver and find that diving this BCD is a dream.
---------- Post added August 18th, 2014 at 07:07 AM ----------
You're right - When wearing thick neoprene, you must make adjustments during the dive --- but much less so than with a conventional BCD. Venting is well controlled and, in fact, one of the advantages of this type of system is that you can vent from any body position - you don't have to position the air bubble toward the venting port.
---------- Post added August 18th, 2014 at 07:10 AM ----------
We are looking for a partner with an established marketing presence. There is a legitimate concern that the costs associated with this feature might be a deterrent. It would probably retail in the $400 rqnge.
---------- Post added August 18th, 2014 at 07:12 AM ----------
There is a separate low pressure manual inflator.
---------- Post added August 18th, 2014 at 07:21 AM ----------
Thanks for your thoughtful comments. Answering your questions: 1-The primary mode of failure would be a bladder rupture. The bladder has withstood 2000 inflation-deflation cycles on the test bench but that does not insure with certainty that it could not occur. Therefore, the device is designed so that if one bladder ruptures, it is sealed off from the other three. 2-There is a redundant conventional bladder that can be inflated orally. 3-Maximum lift in the prototype is 16 lbs. This would be increased in a production model. The conventional bladder can be expanded for additional lift at the surface. 4-The high pressure venting is not a problem as the venting is through a restrictive orifice. It is actually more controllable than a conventional BCD. Furthermore, venting can be accomplished from any body position.
---------- Post added August 18th, 2014 at 07:23 AM ----------
Although attempts have been made to achieve constant buoyancy with an automatic mechanism, this is not one of them. There is no automation. The bladder simply has different inflation characteristics than a conventional BCD.
---------- Post added August 18th, 2014 at 07:27 AM ----------
With 3 bladders, there is still less "roll" than that experience when shifting body position with a conventional BCD. If 25 % or more lift capacity were lost, and was insufficient to maintain neutral buoyancy, the diver can use an incorporated redundant low pressure bladder system.
---------- Post added August 18th, 2014 at 07:28 AM ----------
Let me clarify. This is not a fixed volume container. It is a high pressure bladder whose volume can be adjusted.
---------- Post added August 18th, 2014 at 07:31 AM ----------
You are right. With a very thick wetsuit, the volume in the bladder must be adjusted during the dive -- just much less so than with a conventional BCD.
---------- Post added August 18th, 2014 at 07:33 AM ----------
This is not a rigid container, It is a high pressure bladder that has an adjustable volume.
---------- Post added August 18th, 2014 at 07:42 AM ----------
Good points. My responses: First of all our system does not have just one "fixed buoyancy". The buoyancy is adjustable, just not affected by depth changes. For the novice, this prevents runaway ascents (and descents). For the more experienced diver --- haven't you ever changed your rig so that your buoyancy is unknown- Then you hit the water and either need to add weight, or add a relatively large amount of air to your bladder to compensate for overweighting. That large amount of air is subject to considerable expansion and contraction during the dive, so you have to make frequent adjustments. If you don't experience either of these scenarios, then you would not derive much benefit from our system.
---------- Post added August 18th, 2014 at 07:48 AM ----------
This system does not have a rigid bladder. It has a high pressure bladder that has adjustable volume but does not change volume significantly with changes in depth.
captain
Contributor
Questions
1-Where is the air sourced from the the LP or HP regulator port and what pressure are the bladders operating at above ambient .
2-Is there any consideration for a stuck open inflater to prevent over inflation to the point of rupture such as on a BC.
3-If higher pressure is required to inflate that is more of a reduction of air available to the diver then with a regular BC that only requires air at ambient, how much would the reduction be.
4-What is the weight of it, is it more or less than a regular BC. When empty how negative is it.
1-Where is the air sourced from the the LP or HP regulator port and what pressure are the bladders operating at above ambient .
2-Is there any consideration for a stuck open inflater to prevent over inflation to the point of rupture such as on a BC.
3-If higher pressure is required to inflate that is more of a reduction of air available to the diver then with a regular BC that only requires air at ambient, how much would the reduction be.
4-What is the weight of it, is it more or less than a regular BC. When empty how negative is it.
Eric Sedletzky
Contributor
Pretty soon divers won't have to know how to dive.
Just like cars, first there was the automatic transmission, then there is development with anti lock brakes, now we have self parking cars, self steering cars, automatic braking. Pretty soon people won't need to know how to drive, it will all be done for them. Pretty soon divers won't need to know how to dive, it will be done for them.
I like to dive because it's a hands on thinking sport, something that's still manual that I can do and get good at. Like working with wood or some other hands on hobby.
If the automatic trend keeps up pretty soon any blob would be able to strap on a tank and go under - propelled by automatic fins or scooter, controlled by an automatic BCD, can't run out of air because a sensor will force the diver to the surface when the air gets low, etc.
I choose to go the other way, towards minimalism....it's a new trend of an old school idea. Modernized, streamlined, making use out of all the great new "simple" gear available to us in this day and age.
The more I dive and learn the more gear I get rid of. I have it down to a bare minimum, just what I need for the dive at hand. Many times I don't even use a BC, and that's with a 7mm suit. If I had the luxury of living somewhere with warm water I would probably never use a BC.
Proper weighting, proper streamlining, keeping skills sharp, staying wet, that's where it's at, not some contrivance to top the "elevator lever".
Just like cars, first there was the automatic transmission, then there is development with anti lock brakes, now we have self parking cars, self steering cars, automatic braking. Pretty soon people won't need to know how to drive, it will all be done for them. Pretty soon divers won't need to know how to dive, it will be done for them.
I like to dive because it's a hands on thinking sport, something that's still manual that I can do and get good at. Like working with wood or some other hands on hobby.
If the automatic trend keeps up pretty soon any blob would be able to strap on a tank and go under - propelled by automatic fins or scooter, controlled by an automatic BCD, can't run out of air because a sensor will force the diver to the surface when the air gets low, etc.
I choose to go the other way, towards minimalism....it's a new trend of an old school idea. Modernized, streamlined, making use out of all the great new "simple" gear available to us in this day and age.
The more I dive and learn the more gear I get rid of. I have it down to a bare minimum, just what I need for the dive at hand. Many times I don't even use a BC, and that's with a 7mm suit. If I had the luxury of living somewhere with warm water I would probably never use a BC.
Proper weighting, proper streamlining, keeping skills sharp, staying wet, that's where it's at, not some contrivance to top the "elevator lever".
Similar threads
