Suunto Nautic S User Guide

Key information during diving

While on the pre-dive screen, you can scroll through the different dive views by pressing the middle button. On a default dive display, you will see the following information:

1. Decompression information

2. Ascent speed with color coding

3. Dive time

4. Depth

5. Switch window with changeable information

6. Arch illustrating key information: no deco limit, tank pressure, time to surface, stop time, compass.

Decompression information:

The decompression area on the screen is fixed and shows the following data in the following situations:

Surface time: When surfacing, the decompression area is replaced with a surface timer. It shows the elapsed time between surfacing from a dive and beginning a descent for the subsequent dive. It shows the time in minutes and seconds up to one hour. Above one hour, the time is displayed in hours and minutes up to 24 hours, and after that, hours up to seven days and then only in days.

No Decompression Limit (NDL): Once a dive has started, the surface timer is replaced with the NDL time. It shows the time remaining in minutes at the current depth until mandatory decompression stops are required. If NDL time is above 99 minutes, it is displayed as >99.

Deco time: If exceeding the NDL time, an alarm is triggered and the NDL time is replaced with the optimum ascent time in minutes (TTS). A Deco badge appears, the NDL arch turns to orange indicating the same TTS time, and the ceiling value appears in the switch window. The ceiling value indicates the decompression stop depth. An alarm is also triggered that can be confirmed by pressing any button. Read more about decompression diving in 9.2 Decompression dives-OL.

Stop time: If a safety stop or deco stop is required during the dive, the NDL or decompression information is replaced with a stop timer counting down the required stop time in minutes and seconds. The stop depth range will be indicated in the depth area. Once the stop is completed, Stop done is displayed in the switch window. You can adjust the safety stop time in the Algorithm settings.

Ascent rate:

During a dive, the bar in the middle of the screen indicates how fast you are ascending. One bar step corresponds to 2 m (6.6 ft) per minute.

The bar is color coded to show the following:

• Gray indicates ascent rate is less than 2 m (6.6 ft) per minute

• Green indicates ascent rate is between 4 m (13 ft) per minute and 8 m (26 ft) per minute

• Yellow indicates ascent rate is over 8 m (26 ft) per minute

• Red indicates ascent rate is 10 m (33 ft) per minute

• Highlighted red indicates ascent rate is over 10 m (33 ft) per minute for 5 sec or longer

Arch illustrating key information

Suunto Nautic S comes with different arches for both Single gas and Multigas modes.

No deco: The arch shows the no deco time in a fixed range from 0 – 99. The arch is green for the range 5 – 99, and orange for the range 0 – 5. If the value is higher than 99, the indicator is stopped at the end.

Tank pressure: The arch shows the tank pressure if the watch is paired with a Suunto Tank POD. The bars on the arch always represent 50 bar. The colors represent certain parts of the range and they are always fixed to:

• Red : 50 bar / 750 psi or less

• Orange: 51 bar – 80 bar / 750 psi – 1000 psi

If no Tank POD is paired or the signal is lost, the arch is gray.

Compass: The arch shows the magnetic north (marked with a red arrow) and the four cardinal directions. See Compass use during diving.

Stopwatch: The arch shows seconds. Once 60 seconds has passed, minutes are marked by a bar. See Stopwatch use during diving.

In addition, there are two dynamic arches:

Stop timer: If a stop is required, the arch shows the value corresponding to the dive view window.

TTS: If exceeding the NDL time, the arch turns orange and shows the Time to surface (TTS). The TTS arch range is fixed to 0 – 50 min. If the value is higher than 50, the indicator is stopped at the end.

Press the middle button to scroll between the arches.

Switch window for scuba diving

The switch window at the bottom of the dive screen can contain different types of information that can be changed by short pressing the lower button.

Switch window	Switch window content	Explanation
	Temperature	The current temperature in degrees Celsius or Fahrenheit, depending on unit settings.
	Max depth	The maximum depth reached during the current dive.
	Clock	The time in a 12- or 24-hour format, based on the time format you set under Time/date settings.
	Battery	The remaining battery level as percentage. See Mandatory dive alarms for battery alarms.
	Tank pressure	The tank pressure in the set unit (bar or PSI) for your active gas if linked to a Tank POD. If you have paired 2 tank pods to the same gas, the switch window will be a dual field.
	Gas consumption (L/min or cu ft/min)	Gas consumption refers to your real-time consumption rate of gas during a dive. The actual gas consumption rate is measured in liters per minute (cubic feet per minute) and calculated for the current depth. See Gas consumption for more information.
	Gas time	Gas time refers to the time you can stay at the current depth. See Gas time for more information.
	Safety stop	A three (3) minute safety stop is always recommended for every dive over 10 meters (33 ft). Once exceeding 10 m (33 ft), the 3 m (9.8 ft) minimum depth of the safety stop is displayed in the switch window. Safety stops can be set to three (3), four (4), or five (5) minutes in the Algorithm settings.
	Time to surface (TTS)	The time to surface refers to the ascent time in minutes to ascend to the surface with given gases including all required decompression stops.
	Actual ppO2	The current partial pressure of the active gas. Partial pressure is the fraction of oxygen in the gas at the current depth. The value is always in absolute atmospheres (ATA) of pressure. (1 ATA = 1.013 bar) If the ppO2 exceeds the preset limit for the gas, the switch window turns yellow and triggers an alarm. If the ppO2 exceeds the maximum partial pressure limit of 1.6, the switch window turns red until you ascend shallower than the MOD depth.
	MOD	Maximum Operating Depth. MOD is the depth at which the partial pressure of oxygen (ppO2) of the gas mix exceeds a safe limit.
	Average depth	The average depth of the current dive is calculated from the moment the start depth is exceeded until the dive ends.
	Sunset ETA	The estimated time until sunset expressed in hours and minutes. Sunset time is determined via GPS, so your watch relies on the GPS data from the last time you used GPS.
	Gradient factors	The Gradient Factor value you have defined in the Algorithm settings. See Algorithm settings and Gradient Factors for more information about the dive algorithm and Gradient Factors.
	Heading	The compass feature shows heading in degrees and the cardinal and inter cardinal direction. The compass calibrates itself when in use, but if a recalibration is needed, a prompt will pop up. To calibrate the compass, turn and tilt the watch in a figure-8.

Dynamic values

Some values are visible in the switch window by default. The values appear in the window only if they are triggered by an alarm or event.

OTU

Oxygen tolerance unit. It is used to measure the whole-body toxicity, caused by prolonged exposure to high oxygen partial pressures. Suunto Nautic S alarms you when the daily recommended limit reaches 250 (caution) and 300 (warning).

CNS

Central nervous system toxicity. The CNS value is a measure of how long you have been exposed to elevated partial pressures of oxygen (ppO2), displayed as a percentage of a maximum allowable exposure. Suunto Nautic S alarms you when CNS% reaches 80% (caution) and when the 100% limit (warning) is exceeded.

The oxygen exposure calculations are based on currently accepted exposure time limit tables and principles. The limits are based on the NOAA Diving Manual. The CNS percentage is calculated continuously when in diving mode, even when on the surface.

In addition to this, the dive computer uses several methods to conservatively estimate the oxygen exposure. For example:

• The displayed oxygen exposure calculations are raised to the next higher percentage value.

• The CNS% limits up to 1.6 bar (23.2 psi).

• The OTU monitoring is based on the long-term daily tolerance level and the recovery rate is reduced.

At the surface and after the dive has ended, the CNS decreases with a half time of 90 min. For example, if the CNS is 100 after the dive, 90 min later it will be decreased to 50 and then after another 90 min to 25.

Ceiling

When mandatory decompression stops are required, a ceiling value appears in the switch window. Suunto Nautic S shows the ceiling value always from the deepest stop. You must not ascend above the ceiling during your ascent. Read more about decompression diving in Decompression dives.