Capillary Depth Gauge - anachronism or reference...

[Valeriy_Kulaha]

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.

I do not advertise my plastic product. All physicists know that Boyle's depth gauge is a reference one, since it has no transmission parts, and therefore no possible sources of error. It's like a mercury thermometer or a mercury barometer. These are direct-reading devices.
Manufacturers do not do a lot of things that are inexpensive - it is more profitable to sell an expensive product. But in many countries of the world, the cost of one Sherwater's computer is equal to half a year, or even more, the income of a worker. Well, why do millions of schnorcheler need a computer?
And another question - when was the last time you checked your computers in a service center?

 

[Belzelbub]

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?"

First, the capillary gauge is an interesting concept. That said, I don't see it being a solution for me.

I generally wear two computers. A Shearwater Perdix and a Garmin Descent MK2s. As of now, I've not seen any reason to not trust the depth reported by my computers. They both agree, so I'm confident they are both accurate.

To answer your question, if one of my computers were to read 50' (~15M) and the other were to read 65' (~20M), I could determine which one is correct based on knowledge of the dive site. If the bottom is at 55' and I'm a few feet above the bottom, I know that the one reading 65' is not to be trusted.

A wall dive might be a different scenario, but based on the diving that I do, a 5-8M variance would be obvious.

 

[John C. Ratliff]

There are three potential sources of error for a capillary depth gauge, two physical and one mechanical. The first, physical error potential is temperature. When there is a large discrepancy between the temperature of the air/gauge before enter water, and the water is cold, there can be an error as the air inside the captured capillary tube cools, and contracts somewhat. The second potential for error is altitude, whereby the air is thinner than at sea level. In both cases, the capillary depth gauge will read deeper than the actual depth, which is a safety factor.

The third potential is that the air column, when banged hard, could separate and have two air columns inside the tube, separated by an area of water. This is unlikely, but I have seen it happen. The gauge then needs to come out of the water, and the water inside the tube needs to be removed (usually placing the gauge in the sun will do that easily in an hour or two).

When I get to my to my other desktop computer, I’ll upload a correction table for both analog (Bourden tube) and capillary depth gauges at various altitudes. Also enclosed is a Skin Diver Magazine article by E.R. Cross titled "High Altitude Decompression," which includes the Cross Altitude Dive Tables.

I am one of those older divers, who would prefer to use a depth gauge/tables backup to buying two dive computers. Different manufacturers also have different means of testing their algorithms, which many don’t make public (as we discussed in the discussion in Basic Scuba here about tables not now being taught to divers). The other thing is that a cheap, almost foolproof alternative to buying a dive computer is not going to be supported by diving equipment manufacturers, as they must have profits to survive, and a capillary depth gauge simply won’t supply that profit. They must make money, and what better way than to say that their computers may be subjected to failure, and that all divers should have two dive computers.

SeaRat

PS, the photo is of me diving at High Rocks on the Clackamas River last summer.

 

[jale]

Hi
Just for your information, Sunline is still making a capillary gauge and you can buy one quite easliy in Europe.
I have one and had used it when I dive oxy reb but I prefer a burbon gauge: Sunline is doing some nice one for shallow oxy diving

 

[Valeriy_Kulaha]

There are three potential sources of error for a capillary depth gauge, two physical and one mechanical. The first, physical error potential is temperature. When there is a large discrepancy between the temperature of the air/gauge before enter water, and the water is cold, there can be an error as the air inside the captured capillary tube cools, and contracts somewhat. The second potential for error is altitude, whereby the air is thinner than at sea level. In both cases, the capillary depth gauge will read deeper than the actual depth, which is a safety factor.

The third potential is that the air column, when banged hard, could separate and have two air columns inside the tube, separated by an area of water. This is unlikely, but I have seen it happen. The gauge then needs to come out of the water, and the water inside the tube needs to be removed (usually placing the gauge in the sun will do that easily in an hour or two).

When I get to my to my other desktop computer, I’ll upload a correction table for both analog (Bourden tube) and capillary depth gauges at various altitudes. Also enclosed is a Skin Diver Magazine article by E.R. Cross titled "High Altitude Decompression," which includes the Cross Altitude Dive Tables.

I am one of those older divers, who would prefer to use a depth gauge/tables backup to buying two dive computers. Different manufacturers also have different means of testing their algorithms, which many don’t make public (as we discussed in the discussion in Basic Scuba here about tables not now being taught to divers). The other thing is that a cheap, almost foolproof alternative to buying a dive computer is not going to be supported by diving equipment manufacturers, as they must have profits to survive, and a capillary depth gauge simply won’t supply that profit. They must make money, and what better way than to say that their computers may be subjected to failure, and that all divers should have two dive computers.

SeaRat

PS, the photo is of me diving at High Rocks on the Clackamas River last summer.

The Clapeyron formula for an ideal gas uses absolute temperature with absolute zero -273
Therefore, a decrease in water temperature during immersion by 15 degrees will amount to a volume change of only 5 percent. Moreover, this is also true for the Bourdon air tube and the membrane.
Piezoelectric computer's sensors are even more sensitive to temperature changes.

 

[Valeriy_Kulaha]

Hi
Just for your information, Sunline is still making a capillary gauge and you can buy one quite easliy in Europe.
I have one and had used it when I dive oxy reb but I prefer a burbon gauge: Sunline is doing some nice one for shallow oxy diving

The Polish company Gramy is preparing to produce a capillary depth gauge based on my Patent US # 11525658.
Weight - less than 20 grams, thickness - 6 mm, diameter - 45 mm.
Suitable even for kids and snorkelers. Price - about 25-30 USD
It will be a very strong and reliable case. We calculate the possibility of a lifetime warranty, like Zipo lighters.

 

[Lorenzoid]

The Polish company Gramy is preparing to produce a capillary depth gauge based on my Patent US # 11525658.
Weight - less than 20 grams, thickness - 6 mm, diameter - 45 mm.
Suitable even for kids and snorkelers. Price - about 25-30 USD
It will be a very strong and reliable case. We calculate the possibility of a lifetime warranty, like Zipo lighters.

Congratulations! Relatively few independent inventors who obtain their own patents are able to monetize them.

 

[Tassie_Rohan]

Do let us know when Gramy has a prototype out: be nice to see it.

While digital gauges/computers are accurate, some folks such as myself like the look and feel of an analogue gauge.

If you are looking for a market opportunity, consider combining your capillary gauge with a simple watch with a moveable needle/hand to track elapsed time. I have been looking for a simple watch/depth gauge that can be worn as a backup on a dive, and as a watch on surface (but keeping the look of a diving gauge).

Cheers
Rohan

 

[rx7diver]

... modern dive computers have become the standard and older style instruments are now viewed as obsolete. ...

Analog depth gauges are a novelty at best, no matter how good they are at this point. ...

Sometimes some of you crack me up! IJS.

rx7diver

 

[runsongas]

i'll stick with my shearwater