phillydiver
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it looks like most quality analog depth gauges go to 200 feet -i saw a few go to 230 feet- i once heard accuracy beyond 200 feet is preally poor and that getting a depth gauge beyond 200 is a waste - is this true?
depth gauge max
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Bobby
Contributor
For 99% of divers it is a waste due to the recreational limits. I have one gauge that is accurate past 1000 ft., one that goes to 330 ft., and bought a back up with out knowing it only went to 250 ft. A lot of my dives are deeper than that and it is now just a watch for the most part due to the depth limitation (read the fine print very carefully) So it really depends on the diving conditions that you are in. Again 99% of the time 200 ft. is more than enough. Beyond that depth the cost expands exponentialy compared to accuracy.
It's a good idea to know the limits of your gear but if you aren't diving below recreational limits, having a depth gauge that will offers limited advantage. Most analog gauges are rated to 200 feet, which is deep enough for the normal diver. It's been my experience that, within the limits defined by the manufacturers, most depth gauges are good to within a foot or so.
If you need to go deeper, the depth gauge of choice seems to be the Uwatec Digital Depth Gauge, aka bottom timer.
If you need to go deeper, the depth gauge of choice seems to be the Uwatec Digital Depth Gauge, aka bottom timer.
It's just like the Speedometer in a car. All go past what the speed limits are in the U.S. but it doesn't mean you have to use the whole thing.
It is better to have a buffer in the gauge instead of going to 130 and stopping. If for some reason, intentional or not, you passed the 130 mark how would you know how deep you went?
Gary D.
It is better to have a buffer in the gauge instead of going to 130 and stopping. If for some reason, intentional or not, you passed the 130 mark how would you know how deep you went?
Gary D.
Xanthro
Guest
As the depth rating goes up the cost does as well. Most common gauges stop at 200 because rec divers are very unlikely to go that deep.
Charlie99
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Readings beyond 200' are not only a waste, but also a hinderance for someone diving a single tank. On a gauge (at least the bourdon tube/linear scale type) with 1,000' max depth, it would be difficult to accurately read your depth in the shallower ranges where you are actually diving.phillydiver:
Just imagine what it would be like trying to drive around town in a car with a speedometer with a max speed of 750mph.
The type of gauge design is also a large factor in how useable deeper depth readings may be.
Most electronic depth gauges and computers are accurate to plus or minus 1% across their entire range, which is only a potential error of 2 ft at 200'. The nice part is that this ability to read dephts precisely is present across the scale. The bad news is that it is battery dependent and more prone to failure.
Analog gauges can be just as accurate but have displays that are less precise and less easy to read as accurately . Mechanically speaking there are guages that are strictly linear in their display so that the space allowed to show 0 to 10 ft of depth will be the same as the space allowed to show 140 to 150 ft, 190- 200 ft or 230 to 240 ft. The good news here is that you do not lose precision at depth but the bad news is that you do not have that much to start with. In this case a gauge that reads to only 150 ft (ie only has to accommodate depth graduations of 0 to 150 ft in the space available) is much more preferable to gauges that reads to 200 or 240 ft, as long as you are never going to exceed 150 ft. These gauges by design have a needle that will move about 7/8ths of the way around the gauge before reaching the maximum depth so the space available to accomodate the depth markings is limited.
There are also gagues that will allow the needle to move around the gauge a bit more than a turn and a half. These gauges also allow more precise reading at shallow depths. The space allowed for 0 to 10 ft may be marked in 2 ft increments and will take the same space on the face as the display of, for example, 100 ft to 140 ft. Obviously the ability to precisely tell your depth is much greater at shallow depths. In many cases at depths between 100 and 190 ft, (depending on the particular gauge) the needle will also start it's second lap around the gauge face. This could theoretically cause problems at depth on air or nitrox as a narced diver could read 150 ft as being for example 20 ft., but you'd have to be really narced and totally clueless to do it.
With regard to analog gauges I prefer this type as it allows much greater precision at shallower depths in the 0 to 60 ft range where most rec divers spend most of their time and also where decompression divers do the majority of their deco stops as in that situation being able to tell if you are at 30 ft or 32 ft is potentially important.
Capillary depth guages use air trapped in a tube running around the gauge face to show depth. The bubble is compressed and there it ends will corrospond with the depths on the gauge face. They are super simple, super reliable, generally very thin and are the only design that will display readings in theoretical depth at altitude. In the same manner that pressure increases in a greater ratio at shallow depths (ie increases 100% between 0 and 33 ft, but only by 25% between 99 abd 132 ft.) capillary gauges have more room for graduated marks between 0 and 33 ft than they do for marks between 100 and 130 ft. Capillary gauges also by design are limited to about 5/6ths of a turn around the gauge face, so in that regard they incorprate the best feature of one mechancial design (lots of room for precise reading at shallow depths) and the worst features of the other mechanical design (needle travel limited to about 7/8ths of the gauge face). They can also be very hard to read in low light conditions or with a llight.
Most electronic depth gauges and computers are accurate to plus or minus 1% across their entire range, which is only a potential error of 2 ft at 200'. The nice part is that this ability to read dephts precisely is present across the scale. The bad news is that it is battery dependent and more prone to failure.
Analog gauges can be just as accurate but have displays that are less precise and less easy to read as accurately . Mechanically speaking there are guages that are strictly linear in their display so that the space allowed to show 0 to 10 ft of depth will be the same as the space allowed to show 140 to 150 ft, 190- 200 ft or 230 to 240 ft. The good news here is that you do not lose precision at depth but the bad news is that you do not have that much to start with. In this case a gauge that reads to only 150 ft (ie only has to accommodate depth graduations of 0 to 150 ft in the space available) is much more preferable to gauges that reads to 200 or 240 ft, as long as you are never going to exceed 150 ft. These gauges by design have a needle that will move about 7/8ths of the way around the gauge before reaching the maximum depth so the space available to accomodate the depth markings is limited.
There are also gagues that will allow the needle to move around the gauge a bit more than a turn and a half. These gauges also allow more precise reading at shallow depths. The space allowed for 0 to 10 ft may be marked in 2 ft increments and will take the same space on the face as the display of, for example, 100 ft to 140 ft. Obviously the ability to precisely tell your depth is much greater at shallow depths. In many cases at depths between 100 and 190 ft, (depending on the particular gauge) the needle will also start it's second lap around the gauge face. This could theoretically cause problems at depth on air or nitrox as a narced diver could read 150 ft as being for example 20 ft., but you'd have to be really narced and totally clueless to do it.
With regard to analog gauges I prefer this type as it allows much greater precision at shallower depths in the 0 to 60 ft range where most rec divers spend most of their time and also where decompression divers do the majority of their deco stops as in that situation being able to tell if you are at 30 ft or 32 ft is potentially important.
Capillary depth guages use air trapped in a tube running around the gauge face to show depth. The bubble is compressed and there it ends will corrospond with the depths on the gauge face. They are super simple, super reliable, generally very thin and are the only design that will display readings in theoretical depth at altitude. In the same manner that pressure increases in a greater ratio at shallow depths (ie increases 100% between 0 and 33 ft, but only by 25% between 99 abd 132 ft.) capillary gauges have more room for graduated marks between 0 and 33 ft than they do for marks between 100 and 130 ft. Capillary gauges also by design are limited to about 5/6ths of a turn around the gauge face, so in that regard they incorprate the best feature of one mechancial design (lots of room for precise reading at shallow depths) and the worst features of the other mechanical design (needle travel limited to about 7/8ths of the gauge face). They can also be very hard to read in low light conditions or with a llight.
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