Capillary Depth Gauge - anachronism or reference...

[runsongas]

Analog depth gauges are a novelty at best, no matter how good they are at this point. The disadvantages of using tables and square profiles are just too significant. Also compounded by needing a separate device to handle the timing. Even analog compasses are losing ground these days as more dive computers are integrating them.

 

[Valeriy_Kulaha]

Analog depth gauges are a novelty at best, no matter how good they are at this point. The disadvantages of using tables and square profiles are just too significant. Also compounded by needing a separate device to handle the timing. Even analog compasses are losing ground these days as more dive computers are integrating them.

This is how a person becomes a slave to technology!
The only thing that does not allow falling into deep pessimism is the hope that boyscouts are still taught to find the East without an electronic compass.
By the way, I am Ukrainian and I know how you can wake up in one morning in a completely different world, where it becomes a big problem just to charge your phone.

 

[Valeriy_Kulaha]

The first question is not really an issue with a quality contemporary computer. As an example, the Perdix is accurate to the nearest one foot of depth and is 100% reliable for accurate depth down to 435 feet. Granted, a computer can fail and while some carry an additional backup gauge, the trend is to wear two computers. I understand your position, I was diving long before computers so when they came out, they had a lot of issues and many did not trust them. Those days are long gone. The Navy doctor is simply pointing out that everyone has different physiology and even if the computer says you are good, you still might experience a DCS episode. Just responding to your initial inquiry “could this be helpful” and with the current trends in diving and what is available, I see a very limited application for what you are proposing. Again, JMHO so don’t let that dissuade you from moving forward with your project.

I want to add that modern computers are 100% reliable. Modern parachutes are also reliable, but иy law (FAA regulations), all intentional parachute jumps must be made with a single harness, dual parachute system with both a main canopy *AND* a reserve canopy.
And here again we return to the reliability of the second computer and our ability to visually assess the correctness of its work in a critical situation. It looks like we only have faith in the divine name and the word of honour of the manufacturer!
And again the question is which of the two computers shows correctly! It seems that at present this issue can only be solved with a rope with knotted depth marks, since a capillary depth gauge is almost impossible to buy.
While this might solve the issue quickly and reliably...

 

[Angelo Farina]

And again the question is which of the two computers shows correctly! It seems that at present this issue can only be solved with a rope with knotted depth marks, since a capillary depth gauge is almost impossible to buy.
While this might solve the issue quickly and reliably...

The problem of using two computers is that, when they diverge significantly, you are not sure which of the two is correct...
It the problem is just assessing if you are close to NDL, then of course you follow the most restrictive one.
But when you need to make deco stops, you must be sure of the correct depth: too little or too much are both wrong!
And here your trusty analog meter with no mechanical parts in movement comes handy.
Please note that I am an engineer, and I designed and patented electronic measuring systems.
I am also a software developer of some commercial programs for acoustical simulations and signal processing.
Despite this (or, perhaps, exactly because I know how they are designed, maufactured and programmed), I do NOT thrust 100% electronics devices, particularly in harsh environments, such as underwater.
I prefer to backup my computer with an analog pressure gauge and an analog depth meter.
For time, I trust the crown of my old Seiko watch, which served me well in the past 50 years.

 

[DAJ]

There is a reason the manufacturers that are still in business today that use to make them in the 70s no longer offer them and haven’t for decades. There is no market for them. Justify it as you will but you can “what if” this all day. It still doesn’t create a need in contemporary diving. Like I posted before, if you feel the need is there then that should be enough for you to proceed and market them.

 

[Valeriy_Kulaha]

There is a reason the manufacturers that are still in business today that use to make them in the 70s no longer offer them and haven’t for decades. There is no market for them. Justify it as you will but you can “what if” this all day. It still doesn’t create a need in contemporary diving. Like I posted before, if you feel the need is there then that should be enough for you to proceed and market them.

And I think because diving began to be managed by an accountant. Both in commercial training and in production. It is more profitable to sell three computers to a teapot than one watch with a depth gauge.
Let's remember NGA Diving Manual:

E. Depth gauges shall be tested:
1) Every year against a master reference gauge, with no deviation greater than
+3.0/-0.0 fsw between any two (2) equivalent gauges; or
2) When there is a discrepancy greater than two (2) percent of full scale between
any two (2) equivalent gauges.
F. Submersible pressure gauges shall be tested annually against a master reference
gauge, with no deviation greater than +/– 10 percent of scale.
5.6.6 Gauges and Timekeeping Devices.
A. A timekeeping device and gauges indicating diver depth that can be read at the
surface shall be available at each diving location.
B. All depth gauges shall be deadweight tested or calibrated against a master reference
gauge every six (6) months, and when there is a discrepancy greater than two (2)
percentage points between any two (2) equivalent gauges

And now let's read the operating instructions for all dive computers of all manufacturers.
For example the best Shearwater Peregrine:

This computer has bugs. Although we haven’t found them all yet, they are there. It is certain that there are things that this computer does that either we didn’t think about or planned for it to do something different. Never risk your life on only one source of information. Use a second computer or tables. If you choose to make riskier dives, obtain the proper training and work up to them slowly to gain experience.
This computer will fail. It is not whether it will fail but when it will fail. Do not depend on it. Always have a plan for how to handle failures. Automatic systems are no substitute for knowledge and training.
No technology will keep you alive. Knowledge, skill, and practiced procedures are your best defense (except for not doing the dive, of course).

Now let's try to answer the question, which option is more reliable:
- two computers
- computer and capillary depth gauge

 

[Whitrzac]

2 computers, without question.

Depth is irrelevant without a timer and printed deco tables.

 

[Valeriy_Kulaha]

The first question is not really an issue with a quality contemporary computer. As an example, the Perdix is accurate to the nearest one foot of depth and is 100% reliable for accurate depth down to 435 feet. Granted, a computer can fail and while some carry an additional backup gauge, the trend is to wear two computers. I understand your position, I was diving long before computers so when they came out, they had a lot of issues and many did not trust them. Those days are long gone. The Navy doctor is simply pointing out that everyone has different physiology and even if the computer says you are good, you still might experience a DCS episode. Just responding to your initial inquiry “could this be helpful” and with the current trends in diving and what is available, I see a very limited application for what you are proposing. Again, JMHO so don’t let that dissuade you from moving forward with your project.

Read the manufacturer's instructions for the same Perdix on page 3

 

[Valeriy_Kulaha]

2 computers, without question.

Depth is irrelevant without a timer and printed deco tables.

Two computers is good! BUT my firsh question never got answered:
"If you see that your main computer and spare computer have a difference in depth readings of 5 or 8 meters, which computer will you use to continue diving. On what basis will you make your choice?"
Therefore, for the safety of diving, you still need to have three computers - then most likely it will be possible to determine one that will be faulty. And it would be even better to have four - the probability of calculating a computer with an error will be higher. But even four computers will not replace one reference sensor.
Since the instructions for each computer indicate the manufacturer:

This computer has bugs. Although we haven’t found them all yet, they are there. It is certain that there are things that this computer does that either we didn’t think about or planned for it to do something different. Never risk your life on only one source of information. Use a second computer or tables. If you choose to make riskier dives, obtain the proper training and work up to them slowly to gain experience.
This computer will fail. It is not whether it will fail but when it will fail. Do not depend on it. Always have a plan for how to handle failures. Automatic systems are no substitute for knowledge and training.
No technology will keep you alive. Knowledge, skill, and practiced procedures are your best defense (except for not doing the dive, of course).

Old divers who lived to see their gray hairs will tell you that the most safety option is an watch with capillary depth gauge like Oris.

 

[DAJ]

I am an old diver (40+ years) and most of my hair is gone not gray. Now we are quoting legal directed disclaimers to justify your plastic disk. People have answered the question, you’re just not seeing it. The chance of a Perdix failing is extremely low, the chance of two computers failing at the same time is so remote that it’s not ever worth mentioning. I see you pushing this on other sites but you just can’t take the hint. While you may sell off a couple of them, you are trying to create a solution for a problem that doesn’t exist. Again, if there was still a need for this, they would still be commercially available. If, and that is a remote “if” I have two computers are giving me two different depth readings, you go with the computer that gives you the deeper reading, no big deal.