Wrist Mounted Depth Gauge

[Nemrod]

Don't get a capillarry guage, they don't work very well, older guages are better than newer in most cases. The USD Calypso is good, their expanded depth unit that says made in France is good, the oil filled ones from the early 60s are good, the Voits with the big orange faces are good, the ones that were made by Taylor and by Taylor for Voit that read to 140 feet work but they are not that great, any Tekna or Oceanic, the ScubaPros that read to 500 feet are good etc.

I don't know what a "standard wrist mount boot" is--never seen one--can somone please show an example. N

 

[miketsp]

If you get hold of any analog cylindrical depth gauge you could try molding your own boot using silicone sealant. All you need is a tin or a jar with an internal diameter about 1/2" larger than the gauge to serve as a mold. If you use a glass jar just cut the neck off with a glass cutter. Spray the inside of the mold and the gauge with silicone spray before molding - this will act as a demoldant. Squeeze about 1/2" silicone sealant into the bottom, it doesn't have to be very flat and then position the gauge in the middle and press firmly until the silicone underneath starts to rise around the sides. Then inject more silicone around the edge to complete the walls and partially cover the face. Leave it 24 hours to set and then pull the whole thing out.
(If really necessary break the glass or cut the tin.) Remove the gauge from the "boot" and trim the boot with a sharp knife. Cut slots for a strap.
If you want a good finish you can cover the center of the face with a wooden or plastic disk (bottle top) while molding the top of the walls.
It's not that difficult to mold a nice looking boot.
If you have thick strap you can mold the gauge with a piece of plastic strip underneath it. This is later removed and will leave a slot for the strap to pass.

 

[dimitrik]

Don't get a capillarry guage, they don't work very well, older guages are better than newer in most cases. The USD Calypso is good, their expanded depth unit that says made in France is good, the oil filled ones from the early 60s are good, the Voits with the big orange faces are good, the ones that were made by Taylor and by Taylor for Voit that read to 140 feet work but they are not that great, any Tekna or Oceanic, the ScubaPros that read to 500 feet are good etc.

I don't know what a "standard wrist mount boot" is--never seen one--can somone please show an example. N

Leisurepro has a wrist boot for 15 bucks. I'm not sure if depth guages are the same size as compass' and some computers, but if they are, wouldn't something like this work?

http://www.leisurepro.com/Catalog.aspx?op=ItemDisplay&ProductID=WB

 

[Nemrod]

Thanks for the link to the "boot". I might order one and see if it fits anything I have. I think one can see from my attached thumbnail that dive depth guages come in many differening sizes and shapes. One of my USD units I have and that big orange Voit is so heavy I can remove weight when I dive it or have to add weight on the other side for trim--lol. That boot might fit some of the more recent plastic depth guages---hard to say. N

 

[Muzzwezz]

Thanks Mike S, great idea i dident think about looking on E-Bay ill have alook around & thanx for the links.

 

[mike_s]

No problem.

I've never "checked" my capilary depth gauge to compare it to a normal gauge. I didn't know they are that inaccurate. I guess I could take both down sometime and compare them. I suggested it because it is smaller than a normal gauge.

I'm almost afraid to ask Nemrod why he has so many of them? heh.

 

[Muzzwezz]

No problem.

I've never "checked" my capilary depth gauge to compare it to a normal gauge. I didn't know they are that inaccurate. I guess I could take both down sometime and compare them. I suggested it because it is smaller than a normal gauge.

I'm almost afraid to ask Nemrod why he has so many of them? heh.

this isent my field of expertise, infact i dont think i have one but, what is the difference between a Oli/Normal/Capilary gauge?

 

[mike_s]

The capilary gauge has a small capilary tube (remember those from chemisty class?) built into it that allows water in a very tight small tube. As you go deeper the pressure pushes the air farther into the tube which is on a background of Numbers that you can then reference for depth. Because it has no moving parts and only a glass tube in it and a set of reference numbers, it is very thin which makes a nice feature about wearing on your wrist. I guess it'd be easy to break that tube also and is more fragile than the oil one. The tube I guess isn't as accurate but I don't have a good answer besides it's an air bubble and maybe more prone to error.

An oil gauge is obviousely oil filled and has some sort of pressure port which then somehow turns the needle on a background of reference numbers. I know know besides that how the pressure affects the needle and makes it move. maybe it's a spring? anyone else know this?

 

[Muzzwezz]

The capilary gauge has a small capilary tube (remember those from chemisty class?) built into it that allows water in a very tight small tube. As you go deeper the pressure pushes the air farther into the tube which is on a background of Numbers that you can then reference for depth. Because it has no moving parts and only a glass tube in it and a set of reference numbers, it is very thin which makes a nice feature about wearing on your wrist. I guess it'd be easy to break that tube also and is more fragile than the oil one. The tube I guess isn't as accurate but I don't have a good answer besides it's an air bubble and maybe more prone to error.

An oil gauge is obviousely oil filled and has some sort of pressure port which then somehow turns the needle on a background of reference numbers. I know know besides that how the pressure affects the needle and makes it move. maybe it's a spring? anyone else know this?

thanks for that although i am stil doing "thoes chemistry lessons" although not used a capilary tube yet, only done thoes in biology. anyways thanks for that tis been useful

 

[Nemrod]

As explained by several the capillary guage uses a tube which has a small inside diameter. One end is open to the ambient pressure and the other is closed. Water enters the open end and then as pressure increases the air is compressed that is trapped and it is the difference in refractivity of the air trapped in the tube and the water in the tube that gives the read out indication. Temperature and accumulation of debris in the tube affect the operation and they are diffucult to clean.
Most of the depth guages that I have in the picture, though at least one is a capillary and I have several others not shown, are either bourdon tube or diaphram and some of them are air filled and some are oil filled. With a bourdon tube, a curved closed chmaber, it straightens with decreased pressure and curves more with increasing ambient pressure (compared to internal pressure in the bourdon tube). This motion is translated via a mechanical mechanism to the rotary output of the needle from which you take your depth reading. In a diaphram type the motion of the diaphram inward with increasing external pressure similarly drives the mechanical mechanism that rotates the needle.

Thus, in answer to this question, ""I'm almost afraid to ask Nemrod why he has so many of them? heh.""----I don't have many capillary guages. I have diaphram and bourdon tube types and some are oil filled. If that was not the meaning of the question then if you were asking why I have som many analog guages--that was answered as well---I collect them and as well use them.

I also have my own pressure pot, which I built of my own design, using a calibrated known reference guage that I can "dive" a guage to any depth up to 250 feet or so. It is my finding that simple capillary guages are not especially accurate and are most useful at shallow depths up to about 30 feet. On the other hand, my Tekna 240 foot guage, the ScubaPro 500 foot gauge and the orange Voit and several of the USD guages are extremely accurate! As I said, these are tested against a calibrated guage--one that has been certified accurate by a local facility for pressure guage and test instrument certification. Pressure guages are used for things other than diving.
So to summarize, there are three different types of guages leaving aside computer and electronic mechanisms which may derive pressure in a varity of ways, they are:
1. capillary
2. Diaphram
3. bourdon tube

Bourdon tubes may in some cases be closed, a closed chamber, or open to the sea (ambient). Obviouslly those that are open to ambient require cleaning by soaking in distilled water after diving in salt water so that the bourdon tube does not corrode and affect accuracy and function. Most of the quality guages made in the 80s were diaphram units (most--not all). Most guages in the 60s and 70s that I have are bourdon tube types, some open and some closed. The little Taylor made 140 foot gauges I mentioned in another post are an example of a open bourdon tube type. Taylor made some for Voit as well and they had green cases. If you look close in the thumbnail in the other post the black one that reads to 140 feet is the Taylor version. The black USD Calypso is also an open bourdon tube type from circa 1961 and the orange Calypso is oil filed and it is a closed bourdon type. The 70s ScubaPro and the 80s Oceanic and tekna (in the console) are diaphram and the late 60s Voit is also a diaphram. N