There are many gauges on offer. There are three main types: Analog, Digital and Pneumofathometer models. Choosing a gauge that fits your needs is essential for ensuring a safe dive. Keeping your gauge calibrated is also vital for decompression safety, especially at altitudes.
Analog gauges
Analog gauges are used to help divers gauge the depth of the sea. To indicate the depth, they use a needle that pivots around a graduated gauge. These gauges can be worn around the wrist or integrated into a dive computer. Although they are more reliable than the digital gauges, analog gauges can still be used. An analog gauge has one advantage: you won't run out of batteries.
The gauge's face has been designed to be easy-to-read. It comes with numerical increments of depth that range from 10' - 40' and 20'- 150'. The gauge also features a pressure gauge. It displays pressure between 0 and 5000 psi. The red screen is reserved air while the green screen is main air.
Digital models
Divers want to dive long and deep. A digital gauge will not help them achieve this. Temperature variations can alter the pressure differential between the gauge (and the ambient water). A mechanical gauge is more reliable than an electronic device. Not only will it keep track of your dive times and depth but also calculate Nitrogen retention, which can help prevent decompression sickness.
There are two basic types digital gauge diving computers. The hose technique is the simplest. It uses a hose for connecting the dive computer to a high-pressure port on stage 1. Wireless mode uses an electronic transmitter to communicate with the computer. This type is also available in console and wrist-mounted models.
Pneumofathometers
Pneumofathometers measure the depth of the air supply to a diver. These devices measure air pressure at the surface and then indicate the depth in feet or metres. These devices were previously mounted on the hand-cranked compressor that supplied air to standard diving suits. The air supply was free-flow, with no back-pressure.
If you are interested in gauge diving, you should get a gauge with a range from 130 to 160 percent of your diving system's maximum operating pressure. For systems that operate at 3,000psi or higher, a gauge with this range will suffice.
Submersible pressure gauges
A submersible pressure gauge (SPG) is a device that allows scuba divers to keep track of their air pressure. It displays the current depth as well as the direction that the diver is moving. The SPG connects to the regulator using a high pressure line. This arrangement makes it easy for the diver to locate the gauge easily and prevents it from becoming lost. A SPG shows the remaining air pressure in pounds per square inch and is useful for monitoring your air supply while diving.
Scubapro produces an oil-filled analog depth gauge with a Bourdon tube design that measures to a depth of 200 feet. For greater versatility, it also includes a C1-compass that attaches to its console boot. This gauge is perfect for beginners since it is simple to operate.
Compass
A compass that is easy-to-read is the best compass to use for gauge diving. The compass should be large enough to be read underwater and be marked with the appropriate markings. Look for a compass with a bezel with compass headings grouped in 30-degree increments and indicator marks every five degrees.
Side view windows should be included in a compass used for gauge diving. This allows the diver to see which direction the compass is pointed. This allows the diver see the direction that the compass is pointed even in complete darkness.