Gas

Before scuba diving, check or set the gas concentration of your cylinder. Gas concentration is very important for scuba diving, and is used by the decompression algorithm. Recreational diving only needs the oxygen percentage. Technical diving needs oxygen and helium percentages, based on which the device will get the nitrogen percentage.

Water type

The density of sea water is different from the density of fresh water. Higher water density indicates greater pressure at a given depth. Therefore, the depth displayed on the watch differs depending on water type. Setting the water type before diving can help your watch calculate depth more accurately.

GF

The Gradient Factor (GF) is an important part of the decompression algorithm. The factor is usually a paired number, GF LOW/GF HIGH, for example, 30/70. A smaller GF LOW value indicates a deeper stay, and a smaller GF HIGH value indicates a longer duration of decompression stop.

The default GF depends on the diving mode. The default GF for recreational diving is 40/85, and that for technical diving is 30/70, which is more conservative.

It is not recommended to change the default GF unless you fully understand how it works and how it will change decompression calculations.

Partial pressure of oxygen

Partial pressure of oxygen (PO2) is the pressure of oxygen alone in the mixture of gases, which is equal to the atmospheric pressure at the current depth (a multiple of the atmospheric pressure) multiplied by the oxygen percentage.

1. Max partial compression is the maximum oxygen partial pressure threshold while descending. If this threshold is reached, your watch will give an alert. This threshold is also used to calculate the maximum operating depth (MOD).

2. Reduced partial pressure is the maximum oxygen partial pressure threshold while ascending. If this threshold is reached, your watch will give an alert. This threshold is also used to determine when to trigger the cylinder switching reminder.

3. Min partial pressure is the minimum oxygen partial pressure threshold while ascending or descending. When a hypoxic gas (based on the gas concentration) is used incorrectly and oxygen partial pressure is lower than this threshold, your watch will give an alert, indicating oxygen partial pressure is too low.

Safety stop duration

A safety stop is a pause a scuba diver makes during their return to the surface. The purpose of a safety stop is to allow the body to release some inert gases, reducing the risk of decompression sickness. The stop is typically done at a depth of 6 m for 3, 4, or 5 minutes, just before the diver surfaces. When a diver will descend to a depth beyond 30 m or the no-decompression limit (NDL) is less than 5 minutes, the safety stop duration will be 5 minutes.

A safety stop is optional, but recommended to reduce the risk of decompression sickness. If you return to the surface without a safety stop, the safety stop will show as paused, and then disappear when you return to the surface.

Bottom depth

Bottom depth is the depth of the last decompression stop in a technical diver's ascent. This number can be set as needed.

MOD

MOD is the maximum operational depth limit for divers, as allowed by gases. In other words, it is the depth at which the PO2 of mixed gases will almost exceed the max partial compression.

Ascent rate

An ascent rate is how fast a diver ascends during a dive. Scuba diving is configured to a 12 m per minute threshold. The watch will give an alert if this threshold is exceeded. Fast ascents will greatly increase the risk of decompression sickness. It is strongly recommended to keep to a reasonable ascent rate.

PO2

PO2 is calculated during dives in real time according to changes in depth and gas switching. Depending on PO2 threshold settings, the watch will give a reminder or an alert.

Nitrogen load

Diving causes nitrogen to build up in the body. As nitrogen load increases, the diver must take the necessary safety stop and decompression stops to reduce the risk of decompression sickness.

CNS

CNS is a measure of the time a diver is exposed to elevated PO2. CNS is expressed as a percentage of the maximum allowed exposure time. CNS toxicity can show itself in many ways. The most serious way is epileptic spasms, which can lead to drowning.

During a dive, the CNS value will only rise. As PO2 increases, CNS will rise faster, indicating a shorter allowed exposure time. When you return to the surface, CNS will fall gradually, dropping to half of its original value approximately every 90 minutes.

NDL

NDL is the maximum time a diver can spend at the current depth without having to take any decompression stops while surfacing. This time is shown as a countdown timer.

Safety stop

A safety stop is a pause a scuba diver makes during their return to the surface. To reduce the risk of decompression sickness, any dives below 11 m should have a safety stop.

TTS

Time to Surface (TTS) is an estimation of the time required before a scuba diver can surface, after the NDL is over. It includes the durations of decompression stops, the ascent time, and the duration of the safety stop.

Decompression stop

If you exceed the NDL, you must make several decompression stops at specific depths, so that your body can gradually release extra nitrogen underwater. This helps reduce the risk of decompression sickness.

CEIL

CEIL is a decompression ceiling depth when a diver begins their ascent. The closer the diver is to the ceiling, the better the decompression effects. Make sure not to break the decompression ceiling. If you break the decompression ceiling, the watch will give an alert, asking you to return to decompression stop range.

OT+3

This indicates the TTS after you stay at the current depth for an additional 3 minutes.

+OD+5

This indicates the TTS after you descend another 5 m and stay there for 3 minutes.

Surface GF

This indicates the GF HIGH value if you ascend non-stop from the current depth during a technical dive.

Set GF

This indicates the pre-set GF LOW/HIGH values for technical dives, which will affect the depth of the first decompression stop and the total decompression time.

Average depth

This indicates the average depth of a diving session. You can also calculate the average depth by time segment via the Assist button.

Temperature

This indicates the water temperature measured by your watch during diving.

Stopwatch

The stopwatch is used for timing during diving. On the stopwatch screen, you can press buttons to start/pause the timer and reset the stopwatch.

Compass

The compass helps navigate underwater. On the compass screen, you can view and lock/unlock navigation directions.