Intended use

The Suunto EON Steel dive computer is designed for use as an optional diving equipment for recreational diving. Suunto EON Steel is intended for use in various types of scuba diving, for example, for example, air, nitrox, trimix and CCR diving. In scuba diving use Suunto EON Steel dive computer displays important information before, during and after the dive to enable safe decision making. The most important pieces of information are dive depth, dive time and decompression information. In addition, Suunto EON Steel can show the user other dive related values, such as ascent speed, water temperature, and compass direction. It also helps the diver to plan the dive and to follow through the dive plan.

Suunto EON Steel can be used as a standalone product or in combination with the Suunto Tank POD, which measures the tank pressure and transmits the pressure reading information to the Suunto EON Steel dive computer. The combination of the Suunto EON Steel and the Tank POD is a Personal Protective Equipment under the EU Regulation 2016/425 and protects against risks listed under PPE Risk Category III (a): substances and mixtures which are hazardous to health. Backup instruments, for example, depth gauge, submersible pressure gauge, timer, or watch must be used. The diver must have access to decompression tables whenever diving with a dive computer.

Safety

Types of safety precautions

Before you dive

Make sure that you fully understand the use, displays and limitations of your dive instruments. If you have any questions about this manual or dive instrument, contact your Suunto dealer before diving. Always remember that YOU ARE RESPONSIBLE FOR YOUR OWN SAFETY!

Before leaving on a dive trip, inspect your dive computer thoroughly to make sure everything is functioning properly.

At the dive site, perform your manual pre-checks on each device before entering the water.

Dive computer pre-dive safety check

Ensure that:

1. Suunto EON Steel is in the correct dive mode and the display is working as expected.
2. Altitude setting is correct.
3. Personal setting is correct.
4. Deepstops are set correctly.
5. Unit system is correct.
6. Compass is calibrated. Start the calibration manually in the menu under General » Compass » Calibrate to also confirm that the dive computer audible sounds are working. After successful calibration, you should hear a sound.
7. The battery is fully charged.
8. All primary and backup gauges for time, pressure and depth, both digital and mechanical, are showing correct, consistent readings.
9. If Suunto Tank PODs are in use, check that the Tank PODs are properly installed and the tank valve is open. Please see the Suunto Tank POD User Guide for detailed information and proper use.
10. If Suunto Tank PODs are in use, check that connections are working and gas selections are correct.

Safety precautions

Emergency ascents

In the unlikely event that the dive computer malfunctions during a dive, follow the emergency procedures provided by your certified dive training agency to immediately and safely ascend.

Device setup

To get the most out of your Suunto EON Steel, use some time to customize features and displays. Make absolutely sure that you know your computer and have it set up as you want before getting into the water.

To get started:

1. Wake up the device by connecting the USB cable a to PC/Mac.

2. Follow the startup wizard to set up the device. When ready, the device goes to surface state.

3. Fully charge before first dive.

The startup wizard guides you through:

• Language
• Units
• Time format (12h/24h)
• Date format (dd.mm / mm/dd)
• Connecting to Suunto app (recommended)

Display - modes, views, and states

Your Suunto EON Steel has three buttons that have different functions in different views. Short pressing or long pressing them gets you to different functionalities.

By default Suunto EON Steel has four main dive modes: Air/Nitrox, Trimix, CCR and Gauge.

Press and hold the middle button to enter Main menu and select the appropriate mode for your dive under Dive settings » Mode.

Suunto EON Steel automatically restarts to change mode.

Suunto EON Steel has two main views: time/no deco and compass. Change the main view by pressing the middle button. More views are available through customization in Suunto app.

For more detailed information on the views available in the different modes, see Dive modes.

Suunto EON Steel automatically switches between surface and dive state. If you are more than 1.2 m (4 ft) below the water level and the water contact is on, the dive state is activated.

When tank pressure screen is in use, you see the following information:

• Present depth is 19.0 m
• Active gas is Nitrox 32%
• Dive time is 22 minutes
• Tank pressure left is 120 bar
• No decompression time is 50 minutes
• Safety stop is ahead at 3.0 meters
• 21 hours of diving time left before need to recharge
• Temperature is 20°C

The switch window in the bottom right corner can contain different types of information that can be changed by short pressing the lower button.

Icons

Suunto EON Steel uses the following icons:

	No-fly time
	Surface (interval) time
	Battery status (for device: charging, ok, low; for Tank POD: ok, low)
	Battery level - number indicates remaining diving time before need to recharge
	Tank / gas pressure information
	Bluetooth

Product compatibility

Suunto EON Steel can be used together with Suunto Tank POD for wireless transmission of tank pressure to the dive computer. One or more Tank PODs can be paired with the dive computer for multi-gas diving.

You can pair your dive computer with the Suunto app over Bluetooth. You can transfer your dive logs to Suunto app from the dive computer and analyze them on your mobile phone. It is also possible to customize dive modes and change dive computer settings via Suunto app.

You may also connect this dive computer to a PC or Mac with the supplied USB cable to update the dive computer software with SuuntoLink.

With the optional bungee adapter kit for Suunto EON Steel, you can replace the default strap with a bungee cord if desired.

Do not use this dive computer with any unauthorized accessories or attempt to connect wirelessly with mobile apps or equipment not authorized or officially supported by Suunto.

Alarms, warnings, and notifications

Suunto EON Steel has color-coded alarms, warnings and notifications. They are shown prominently on the display with an audible alarm (if tones are on). Alarms are always red. Warnings may be red or yellow. Notifications are always yellow.

When an alarm, warning, or notification occurs, a message is displayed as a pop-up. Pop-up messages can be acknowledged by pressing any button. The information needing attention remains on screen or as a scrollable element in the bottom field until the situation is back to normal.

Alarms are critical events that always require immediate action. When an alarm situation comes back to normal, the alarm will stop automatically.

Alarm	Explanation
	Ascent speed exceeds safe speed of 10 m (33 ft) per minute for five seconds or more.
	Decompression ceiling or mandatory safety stop is broken by more than 0.6 m (2 ft) on a decompression dive. Immediately descend back below ceiling depth and continue to ascend normally.
	Partial pressure of oxygen exceeds safe level (>1.6). Immediately ascend or change to a gas with lower oxygen percentage.
	Partial pressure of oxygen below safe level (<0.18). Immediately descend or change to a gas with higher oxygen percentage.

Warnings alert you to events that can impact your health and safety if you do not take action. Acknowledge the warning by pressing any button.

Warning	Explanation
CNS 100%	Central Nervous System (CNS) Oxygen Toxicity level at 100% limit
OTU 300	Recommended daily limit for Oxygen Tolerance Unit/Oxygen Toxicity Unit (OTU) reached
Depth	Depth exceeds your depth alarm limit
Dive time	Dive time exceeds your dive time alarm limit
Diluent high pO₂	Diluent partial pressure of oxygen exceeds safe level (>1.6); no immediate danger unless diluent is used, e.g. diluent flush
Diluent low pO₂	Diluent partial pressure of oxygen below safe level (<0.18); no immediate danger unless diluent is used, e.g. diluent flush
Gas time	Gas time is below the gas time alarm limit you set, or tank pressure is below 35 bar (~510 psi), in which case gas time is zero.
Safety stop broken	Ceiling of the voluntary safety stop broken by more than 0.6 m (2 ft)
Tank pressure	Tank pressure is below your tank pressure alarm limit. There is a built in 50-bar alarm that cannot be changed. In addition to it there is a configurable tank pressure alarm, you can set to any value between 10-360 bar (145-5221 psi) and your dive computer also shows an alarm when that value and 50 bar (725 psi) pressures are reached. The tank pressure number is forced onto the display and turns yellow after the value you set and red after 50 bar (725 psi).

Notifications indicate events that require preventive actions. Acknowledge the notification by pressing any button.

Algorithm lock

Breaking the decompression ceiling

When you ascend above the ceiling by more than 0.6 m (2 ft), the ceiling parameter turns red, a red arrow pointing down appears, and an audio alarm is generated.

In such event, you should descend below the ceiling level to continue the decompression. If you fail to do so within three (3) minutes, Suunto EON Steel locks the algorithm calculation and displays Locked instead, as shown below. Note that the ceiling value is no longer present.

In this state, you significantly increase your risk of decompression sickness (DCS). Decompression information is not available for the next 48 hours after surfacing.

Algorithm locked

Suunto Fused™ RGBM 2 algorithm is locked for 48 hours if you omit decompression stops for longer than three (3) minutes. When the algorithm is locked, no algorithm information is available and Locked is shown instead. Locking the algorithm is a safety feature, highlighting that the algorithm information is no longer valid.

It is possible to dive with the device when the algorithm is locked, but instead of the decompression information, Locked is shown. Diving while the algorithm is locked resets the algorithm lock time back to 48 hours when you surface.

Altitude diving

The Altitude setting automatically adjusts the decompression calculation according to the given altitude range. You can find the setting under Dive settings » Parameters » Altitude and select from three ranges:

• 0 – 300 m (0 – 980 ft) (default)
• 300 – 1500 m (980 – 4900 ft)
• 1500 – 3000 m (4900 – 9800 ft)

As a result, the allowed no decompression stop limits are considerably reduced.

The atmospheric pressure is lower at high altitudes than at sea level. After traveling to a higher altitude, you will have additional nitrogen in your body, compared to the equilibrium situation at the original altitude. This 'additional' nitrogen is released gradually over time and equilibrium is restored. Suunto recommends that you acclimatize to a new altitude by waiting at least three hours before making a dive.

Before high-altitude diving, you need to adjust the altitude settings of your dive computer so that the calculations take into account the high altitude. The maximum partial pressures of nitrogen allowed by the mathematical model of the dive computer are reduced according to the lower ambient pressure.

NOTE:

If you are doing repetitive dives at an altitude other than the previous dive altitude, change altitude setting to correspond to the next dive after the previous dive ended. This ensures more accurate tissue calculations.

 

 

Ascent rate

 

During a dive, the bar on the left indicates ascent rate. One bar step corresponds to 2 m (6.6 ft) per minute.

The bar is also color coded:

• Green indicates ascent rate is ok, less than 8 m (26 ft) per minute
• Yellow indicates ascent rate is moderately high, 8-10 m (26-33 ft) per minute
• Red indicates ascent rate is too high, over 10 m (33 ft) per minute

When maximum allowed ascent rate is exceeded for five seconds, an alarm is generated. Ascent rate violations result in longer safety stop times and mandatory safety stops.

WARNING:

DO NOT EXCEED THE MAXIMUM ASCENT RATE! Rapid ascents increase the risk of injury. You should always make the mandatory and recommended safety stops after you have exceeded the maximum recommended ascent rate. If this mandatory safety stop is not completed the decompression model will penalize your next dive(s).

 

 

Battery

 

Suunto EON Steel has a rechargeable lithium-ion battery. Charge the battery by connecting Suunto EON Steel to a power source with the included USB cable. As a power source use either your computer USB port or a wall charger.

The battery icon in the upper-left corner of the display shows the battery status. To the right of the battery icon is the estimated remaining dive time in hours.

Icon	Explanation
	Estimated remaining dive time is 27 hours; no immediate need to recharge
	Estimated remaining dive time is three (3) hours or less; recharge needed
	Estimated remaining dive time is less than one (1) hour; recharge immediately. When the charge level drops below two (2) hours, you cannot start a dive with Suunto EON Steel.
	Battery is charging, showing current charge level as remaining dive time

A pop-up message indicates when recharge is needed.

 

 

Bookmark

 

Adding a bookmark (timestamp) to an active log is really easy in Suunto EON Steel. See How to add bookmarks for the procedure.

 

 

Clock

 

Suunto EON Steel's time and date settings are found under Device settings.

Time and date formats are found under Units & formats. For setting, see How to set time and date.

 

 

Compass

 

Suunto EON Steel includes a tilt-compensated digital compass, available as a main view.

Calibrating compass

 

When you first start using Suunto EON Steel, and after each charging, the compass needs to be calibrated and it is required to do so to activate it. Suunto EON Steel displays the calibration icon when you enter the compass view.

During the calibration process, the compass adjusts itself to the surrounding magnetic field.

Because of changes in the surrounding magnetic field, it is recommended to re-calibrate the compass before each dive.

To manually start calibration:

1. Take off your Suunto EON Steel.
2. Keep the middle button pressed to enter the menu.
3. Browse to General » Compass.
4. Press the middle button to enter Compass.
5. Scroll up or down to select Calibrate.
6. Start calibrating the device by trying to move it around the xyz axes of the coordinate system (like you were drawing a small circle) so that the magnetic field is as stable as possible during the calibration. To achieve this, try to keep Suunto EON Steel in the same location and do not move it around using large movements.

7. Repeat the rotation until the compass calibration is successful.

   

8. A sound indicates when the calibration succeeded, and the screen goes back to Compass menu.

NOTE:

If the calibration fails several times in a row, you may be in an area with strong sources of magnetism, such as large metal objects. Move to another location and try to calibrate the compass again.

Setting declination

 

You should always adjust your compass declination for the area where you are diving to get accurate heading readings. Check the local declination from a trusted source and set the value in Suunto EON Steel.

To set declination:

1. Keep the middle button pressed to enter the menu.
2. Browse to General » Compass.
3. Press the middle button to enter Compass.
4. Press the middle button again to enter Declination.
5. Scroll up/down to set the angle of declination: Starting from 0.0º scroll up towards East or down towards West declination. To turn declination off, set declination angle to 0.0º.
6. Press middle button to save changes and go back to the Compass menu.
7. Keep the middle button pressed to exit.

Locking the bearing

 

A bearing is the angle between north and your target. In simple terms, it is the direction you want to travel. Your heading, on the other hand, is your actual direction of travel.

You can set a bearing lock to help you orientate yourself underwater and ensure you maintain your direction of travel. For example, you can set a bearing lock for the direction to the reef before leaving the boat.

You can reset the bearing lock at any time, but you can only clear a bearing lock while at the surface.

To set a bearing lock:

1. Press the middle button to change to the compass view.
2. Hold your Suunto EON Steel in level in front of you, with the top pointing in the direction to your target.
3. Keep the lower button pressed until you see the Bearing locked notification.

Once you have a bearing locked, the lock position is indicated on the compass rose, as shown below.

Below your heading (large number in center of compass), you also see the relative difference between your bearing and your heading. So, for instance, when you want to travel in the exact direction of your bearing, the lower number should be 0°.

If you want to set a new bearing lock, just repeat the same procedure above. Each bearing lock is recorded in your dive log with a time stamp.

To clear the bearing lock from your compass view, you need to return to the surface.

To clear a bearing lock:

1. While in surface state, keep the middle button pressed to enter the main menu.
2. Scroll to General with the upper or lower buttons and press the middle button.
3. Press the middle button to enter Compass.
4. Select Clear bearing with the middle button.
5. Keep the middle button pressed to exit.

 

Customizing dive modes with Suunto app

 

You can easily customize device and dive settings, such as dive modes and views with Suunto app. Create up to 10 different dive modes with up to four custom views each. You can customize the following:

• Dive mode name
• Settings (e.g., personal setting, views, gases)

See How to customize dive modes with Suunto app for more information.

 

 

Decompression algorithm

Suunto's decompression model development originates from the 1980s when Suunto implemented Bühlmann's model based on M-values in Suunto SME. Since then research and development has been ongoing with the help of both external and internal experts.

In the late 1990s, Suunto implemented Dr. Bruce Wienke's RGBM (Reduced Gradient Bubble Model) to work with the earlier M-value based model. The first commercial products with the feature were the iconic Suunto Vyper and Suunto Stinger. With these products the improvement of diver safety was significant as they addressed a number of diving circumstances outside the range of dissolved-gas-only models by:

• Monitoring continuous multiday diving
• Computing closely spaced repetitive diving
• Reacting to a dive deeper than the previous dive
• Adapting to rapid ascents which produce high microbubble (silent-bubble) build-up
• Incorporating consistency with real physical laws for gas kinetics

The Suunto Fused™ RGBM 2 combines and improves widely respected Suunto RGBM and Suunto Fused™ RGBM decompression models developed by Suunto together with Dr. Bruce Wienke. (Suunto dive algorithms are a culmination of expertise and knowledge accumulated over decades of development, testing and thousands upon thousands of dives.)

In Suunto Fused™ RGBM 2 the tissue half-times are derived from Wienke’s FullRGBM where human body is modeled by fifteen different tissue groups. FullRGBM can utilize these additional tissues and model the on-gassing and off-gassing more accurately. The amounts of nitrogen and helium on-gassing and off-gassing in the tissues are calculated independently from each other.

The Fused™ RGBM 2 supports open-circuit and closed-circuit diving up to a depth of 150 meters. Compared to previous algorithms, Fused™ RGBM 2 is less conservative on deep air dives, allowing shorter ascent times. In addition, the algorithm no longer requires tissues to be completely free of residual gases when calculating no-fly times, thereby reducing the required time between your last dive and flying.

The advantage of Suunto Fused™ RGBM 2 is additional safety through its ability to adapt to a wide variety of situations. For recreational divers it may offer slightly longer no- deco times, depending on the chosen personal setting. For open-circuit technical divers it allows use of gas mixes with helium - on deeper and longer dives helium based gas mixes provide shorter ascent times. And finally, for rebreather divers the Suunto Fused™ RGBM 2 algorithm gives the perfect tool to be used as a non-monitoring, set point dive computer.

NOTE:

Suunto EON Steel software version earlier than 2.0 has Suunto Fused RGBM algorithm. When you update the device, the software will update the dive algorithm to latest version.

Diver safety

 

Because any decompression model is purely theoretical and does not monitor the actual body of a diver, no decompression model can guarantee the absence of DCS.

CAUTION:

Always use the same personal and altitude adjustment settings for the actual dive and for the planning. Increasing the personal adjustment setting from the planned setting as well as increasing the altitude adjustment setting can lead to longer decompression times deeper and thus to larger required gas volume. You can run out of breathing gas underwater if the personal adjustment setting has been changed after dive planning.

Oxygen exposure

 

The oxygen exposure calculations are based on currently accepted exposure time limit tables and principles. 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) are based on 1991 NOAA Diving Manual limits.
• The OTU monitoring is based on the long-term daily tolerance level and the recovery rate is reduced.

Oxygen related information displayed by the dive computer is also designed to ensure that all warnings and displays occur at the appropriate phases of a dive. For example, the following information is provided before and during a dive when the computer is set to Air/Nitrox or Trimix (if helium is activated in use):

• The selected O₂% (and possible helium %)
• CNS% and OTU (visible only after your customization in Suunto app)
• Audible notification when CNS% reaches 80%, then warning when 100% limit is exceeded
• Notification when OTU reaches 250 and then warning when 300 limit is exceeded
• Audible alarm when pO₂ value exceeds the preset limit (pO₂ high alarm)
• Audible alarm when pO₂ value is < 0.18 (pO₂ low alarm)

WARNING:

WHEN THE OXYGEN LIMIT FRACTION INDICATES THAT THE MAXIMUM LIMIT IS REACHED, YOU MUST IMMEDIATELY TAKE ACTION TO REDUCE OXYGEN EXPOSURE. Failure to take action to reduce oxygen exposure after a CNS%/OTU warning is given can rapidly increase the risk of oxygen toxicity, injury, or death.

 

 

Decompression dives

 

When on a decompression (deco) dive you exceed the no decompression limit, Suunto EON Steel provides the decompression information required for ascent. Ascent information is always presented with two values:

• ceiling: depth that you should not go above
• asc. time: optimum ascent time in minutes to surface with given gases

WARNING:

NEVER ASCEND ABOVE THE CEILING! You must not ascend above the ceiling during your decompression. In order to avoid doing so by accident, you should stay somewhat below the ceiling.

On a decompression dive, there can be three kinds of stops:

• Safety stop: this is a recommended three-minute stop for every dive over 10 m (33 ft).
• Deepstop: this is a recommended stop when you dive deeper than 20 m (66 ft).
• Decompression stop: this is a compulsory stop on your decompression dive that is for your safety, preventing decompression sickness.

In Dive settings » Parameters, you can

• turn deepstops on or off (it is on by default)
• adjust the safety stop time to be 3, 4 or 5 minutes (default is 3 minutes)
• set last stop depth to 3.0 m or 6.0 m (default is 3.0 m)

The following illustration shows a decompression dive where the ceiling is at 17.7 m (58 ft):

From bottom to top you see the following in the above image:

1. There is a decompression window (Deco window) that is the distance between the decompression ceiling (Deco ceiling) plus 3.0 m (9.8 ft) and the decompression ceiling. So the deco window in this example is between 20.7 m (68 ft) and 17.7 m (58 ft). This is the area where decompression takes place. The closer to the ceiling you stay, the more optimal the decompression time is.

   When you ascend close to the ceiling depth and enter the deco window area, two arrows appear in front of the ceiling depth value. The downward and upward pointing white arrows indicate that you are within the deco window.

2. If you ascend above the ceiling depth, there is still a safe margin area, equaling to ceiling depth minus 0.6 m (2 ft). So in this example, it is between 17.7 m (58 ft) and 17.1 m (56 ft). In this safe margin area, decompression calculation still continues, but you are advised to go down below the ceiling depth. This is indicated by the ceiling depth number turning yellow with a downward pointing yellow arrow in front it.

3. If you go above the safe margin area, the decompression calculation is paused until you go back down below this limit. An audible alarm and a downward pointing red arrow in front of the ceiling depth value indicate unsafe decompression.

   If you ignore the alarm and stay above the safe margin for three minutes, Suunto EON Steel locks the algorithm calculation, and decompression information will not be available anymore on the dive. See Algorithm lock.

Decompression display examples

Suunto EON Steel shows the ceiling value always from the deepest of these stops.

Below is a typical decompression dive view showing ascent time and the first required deepstop at 20.3 meters:

Below is an example of what Suunto EON Steel displays during an optional deepstop:

Below is an example of what Suunto EON Steel displays during a compulsory stop:

NOTE:

If the ceiling is broken for more than 3 minutes, the decompression algorithm gets locked.

With decompression stops, in the continuous ascent mode the ceiling is constantly decreasing while you are near the ceiling depth, providing continuous decompression with optimum ascent time. While in the stepped ascent mode, the ceiling is the same for a specific time and then moves upwards 3 m (9.8 ft) at a time.

NOTE:

It is always recommended to keep close to the decompression ceiling when ascending.

Ascent time is always the minimum time needed to reach the surface. It includes:

• Time required for deepstops
• Ascent time from depth at 10 m (33 ft) per minute
• Time needed for decompression

WARNING:

When diving with multiple gases, remember that the ascent time is always calculated with the assumption that you use all the gases found in the Gases menu. Always check that you have only the gases for your current planned dive defined before you dive. Remove the gases that are not available for the dive.

WARNING:

YOUR ACTUAL ASCENT TIME MAY BE LONGER THAN DISPLAYED BY THE DIVE COMPUTER! The ascent time will increase if you: (1) remain at depth, (2) ascend slower than 10 m/min (33 ft/min), (3) make your decompression stop deeper than at the ceiling, and/or (4) forget to change the used gas mixture. These factors might also increase the amount of breathing gas required to reach the surface.

Last stop depth

 

You can adjust the last stop depth for decompression dives under Dive settings » Parameters » Last stop depth. There are two options: 3 m and 6 m (9.8 ft and 19.6 ft).

By default, the last stop depth is 3 m (9.8 ft). This is the recommended last stop depth.

NOTE:

This setting does not affect the ceiling depth on a decompression dive. The last ceiling depth is always 3 m (9.8 ft).

TIP:

Consider setting the last stop depth to 6 m (19.6 ft) when you dive in rough sea conditions and stopping at 3 m (9.8 ft) is challenging.

 

 

Deco profile

Deco profile can be selected in Dive settings » Parameters » Deco profile.

Continuous decompression profile

Traditionally, since Haldane’s 1908 tables, decompression stops have always been deployed in fixed steps such as 15 m, 12 m, 9 m, 6 m and 3 m. This practical method was introduced before the advent of dive computers. However, when ascending, a diver actually decompresses in a series of more gradual ministeps, effectively creating a smooth decompression curve.

The advent of microprocessors has allowed Suunto to more accurately model the actual decompression behavior. A continuous decompression curve is included in the Suunto Fused™ RGBM 2's working assumption.

During any ascent involving decompression stops, Suunto dive computers calculate the point at which the control compartment crosses the ambient pressure line (that is the point at which the tissue’s pressure is greater than the ambient pressure), and off-gassing starts. This is referred to as the decompression floor. Above this floor depth and below the ceiling depth is the decompression window. The range of the decompression window is dependent on the dive profile.

Off-gassing in the leading fast tissues will be slow at or near the floor because the outward gradient is small. Slower tissues may be still on-gassing and given enough time, the decompression obligation may increase, in which case the ceiling may move down and the floor may move up.

Suunto RGBMs optimize these two contradictory issues through a combination of a slow ascent rate and continuous decompression curve. It all comes down to proper control of the expanding gas during an ascent. This is why all Suunto RGBMs use a maximum ascent rate at 10 m/minute, which has proven over the years to be an effective protective measure.

The decompression floor represents the point at which the Suunto RGBM is seeking to maximize bubble compression, while the decompression ceiling is maximizing off-gassing.

The added advantage of having a decompression ceiling and floor is that it recognizes that in rough water, it might be difficult to maintain the exact depth to optimize decompression. By maintaining a depth below the ceiling but above the floor, the diver is still decompressing, although slower than optimal, and provides an additional buffer to minimize the risk that waves will lift the diver above the ceiling. Also, the continuous decompression curve used by Suunto provides a much smoother and a more natural decompression profile than the traditional “step” decompression.

Suunto EON Steel has a feature of displaying the decompression ceiling. The optimal decompression occurs in the decompression window, which is displayed by both upward and downward arrows. If the ceiling depth is violated, a downward pointing arrow and an audible alarm will prompt the diver to descend back to the decompression window.

Stepped decompression profile

In this decompression profile the ascent has divided into traditional 3 m (10 ft) steps or stages. In this model diver will decompress at traditional fixed depths.

NOTE:

Decompression profile selection is available for EON Steel Black devices and EON Steel devices with software update 2.5.

 

 

Device info

Information about your Suunto EON Steel can be found in your device. This information includes device name, serial number, software and hardware versions and radio compliance information. See How to access device info.

 

Display

Display LED backlight is always on when the device is active. It cannot be turned off, but you can turn the display brightness down to extend battery life significantly.

For display brightness adjustment, see How to change display brightness.

 

 

Dive history

 

Dive history is a summary of all the dives done with your Suunto EON Steel. The history is divided according to the dive type used for the dive. Each dive type summary includes the number of dives, cumulative dive hours and maximum depth. Enter History under General » About EON:

NOTE:

If there is more history information available than can be shown in a single screen, you can scroll through the additional information with the upper and lower buttons.

 

Dive modes

By default, Suunto EON Steel has four dive modes: Air/Nitrox, Trimix, CCR and Gauge (bottom timer). Select the appropriate mode for your dive under Dive settings » Mode.

NOTE:

Suunto EON Steel shows all dive mode names in English. You can change dive mode names via Suunto app.

NOTE:

Air/Nitrox mode is by default in graphical style and all the others in classic visual style. You can change this and other settings, as well as create additional dive modes using Suunto app.

In Suunto app you can create new or edit existing dive modes, modify screen layouts, change helium and multi-gas settings, and change dive type (OC/CC).

The decompression algorithm used in Suunto EON Steel is Suunto Fused™ RGBM 2. For more information about the algorithm, see Decompression algorithm.

Air/Nitrox mode

By default, Air/Nitrox mode is for diving with regular air and diving with oxygen enriched gas mixtures.

Diving with nitrox gas mixture allows you to increase bottom times or reduce the risk of decompression illness. Suunto EON Steel provides you with information to adjust your dive and stay within safe limits.

When diving with nitrox gas mixture, both the percentage of oxygen in your tank and the oxygen partial pressure limit must be entered into Suunto EON Steel. This ensures correct nitrogen and oxygen calculations and the correct maximum operating depth (MOD), which is based on your entered values. The default oxygen percentage (O₂%) setting is 21% (air) and oxygen partial pressure (pO₂) setting is 1.6 bar (23 psi).

NOTE:

When diving with a nitrox gas mixture, Suunto recommends changing the partial pressure to 1.4 bar (20 psi).

Air/Nitrox mode has two views by default:

• No deco

  

• Compass

  

After customizing in Suunto app, two other views are available:

• Tank Pressure - For more information on what is shown on the display, see Tank pressure.

  

• Timer

  

NOTE:

Air/Nitrox dive mode has one active gas by default. You can edit this gas in the device menu where O₂ percentage and pO₂ value can be changed. To enable diving with more than one gas, you need to activate multi-gas diving under Dive settings » Parameters » Multiple gases. After this step you are able to add further gases in the Gases menu. Gas settings can also be customized in Suunto app.

Trimix mode

Trimix dive mode is for diving with a breathing gas consisting of oxygen, nitrogen and helium. With helium added, you can create gas mixtures optimal for your dive.

Trimix mode is typically for deep dives with extended dive time.

Trimix mode has two views by default:

• No deco

  

• Compass

  

After customizing in Suunto app, two other views are available:

• Tank Pressure - For more information on what is shown on the display, see Tank pressure.

• Timer

NOTE:

In Trimix mode, Suunto EON Steel has the multiple gases option automatically turned on.

NOTE:

When diving with helium activated, deepstop is on by default, and it cannot be turned off.

CCR mode

CCR is a dive mode dedicated to rebreather diving.

When you select CCR mode, your device will have two different gas menus: CC gases (closed-circuit gases) and OC gases (open-circuit gases). For more information on diving in CCR mode, see Rebreather diving.

CCR mode has two views by default:

• No deco

  

• Compass

  

After customizing in Suunto app, two other views are available:

• Tank Pressure - For more information on what is shown on the display, see Tank pressure.

• Timer

NOTE:

When diving with helium activated, deepstop is on by default, and it cannot be turned off.

Gauge mode

Use Suunto EON Steel as a bottom timer with Gauge.

Gauge mode is a bottom timer only. It does not use any decompression algorithm, thus it does not include decompression information or calculations.

Gauge mode has two views by default:

• Timer

  

• Compass

  

After customizing in Suunto app, a third view is available:

• Tank Pressure - For more information on what is shown on the display, see Tank pressure.

NOTE:

After diving in Gauge mode, decompression calculation is locked for 48 hours. If during this time you dive again in Air/Nitrox, Trimix or CCR mode, the dive algorithm and the decompression calculation will not be available and Locked will be shown on the screen.

NOTE:

Locked time is set back to 48 hours if you start a new dive while your device is locked.

 

 

Dive planner

The dive planner in Suunto EON Steel helps you to quickly plan your next dive. The planner displays available no decompression time and gas times for your dive based on depth, tank size and gas consumption set.

The dive planner can also help you plan dives in series, taking into account the residual nitrogen from your previous dive(s) based on the planned surface time you enter.

NOTE:

It is important to adjust tank size, tank pressure and personal gas consumption to get the gas calculations right.

See How to plan a dive using the Dive planner for details on planning your dives.

 

 

Enriched Air Nitrox diving use

This device can be used with nitrox breathing gases (also known as oxy-nitrogen).

WARNING:

Do not use nitrox gas mixtures if you do not have proper training. Appropriate training courses about nitrox and oxygen diving are essential prior to the use of this kind of equipment with oxygen content greater than 22%.

WARNING:

In nitrox use, the maximum operating depth and exposure time are dependent on the oxygen content of the gas.

WARNING:

There is a danger when using nitrox that contaminants may give rise to an oxygen ignition.

WARNING:

The use of breathable air according to EN 12021 may contaminate the diving apparatus.

NOTE:

To minimize the risk of oxygen ignition, always open the pressure valve(s) slowly.

For information on Nitrox diving with Suunto Tank POD, see Suunto Tank POD Safety and Regulatory Information delivered with your Tank POD or available at www.suunto.com/SuuntoTankPodSafety.

 

 

Flip display

You can flip the display of Suunto EON Steel to have the buttons on either the left or right side of the dive computer, making it easier to wear on either arm.

Change the button orientation under General » Device settings » Flip display.

Select Buttons right to have the buttons on the right-hand side or Buttons left to have them on the left-hand side.

 

 

Gas consumption

 

Gas consumption refers to your real-time consumption rate of gas during a dive. In other words, it is the amount of gas a diver would use in one minute on the surface. This is commonly known as your surface air consumption or SAC rate.

Gas consumption rate is measured in liters per minute (cubic feet per minute). This is an optional field and needs to be added to your custom dive mode views in Suunto app. In the classic view below, gas consumption rate is in the bottom right corner.

For enabling gas consumption metering, see How to enable gas consumption metering.

 

 

Gas mixtures

 

By default, Suunto EON Steel has only one gas (air) available. The default oxygen percentage (O₂%) setting is 21% (air) and oxygen partial pressure (pO₂) setting is 1.6 bar (23 psi). You can modify O₂ percentage and pO₂ settings in Gases menu.

NOTE:

When diving with a nitrox gas mixture, Suunto recommends changing the partial pressure to 1.4 bar (20 psi).

If you are diving with only one gas, ensure you have only that one gas in the Gases menu. Otherwise, Suunto EON Steel expects you to use all gases in the list and notifies you to change gases during the dive.

If you need more than one gas, activate multi-gas option in your device. Go to Dive settings » Parameters and turn on Multiple gases option.

You need to define all gas mixtures intended to use during the dive in the Gases menu because during your dive the decompression algorithm calculates ascent time using all gases available in the Gases menu.

If you want to use trimix gas mixtures (with helium activated), you need to turn helium on under Dive settings » Parameters. When this is done, you can change helium percentage (He%) for the selected gas in the Gases menu.

You can activate multi-gas diving and helium, configure dive modes and change gas settings using Suunto app, too.

Changing gas during a dive

 

It is important to understand how your Suunto EON Steel device works when you dive with multiple gases. For example, you may have the following gases when diving to 55 m (180.5 ft):

• tx18/45, MOD 62.2 m (pO₂ 1.3)
• tx50/10, MOD 22 m (pO₂ 1.6)
• Nx99, MOD 6 m

While ascending, you are notified to change gas at 22 m (72 ft) and 6 m (20 ft) according to the maximum operating depth (MOD) of the gas. To take a better gas into use, you need to change gas manually by completing the following steps:

1. Press any button to acknowledge the gas change notification.
2. Long press the middle button to see gas options.
3. Scroll with the upper or lower button to the desired gas.
4. Press the middle button to confirm gas selection.

NOTE:

If you press any button while Change gas notification is visible on the device screen, the notification disappears. By pressing a button, you only confirm the notification, but gas is not changed automatically. You should always change gas manually. To change gas, you must follow the above listed steps.

NOTE:

When you select CCR, gas mixtures are divided to open-circuit and closed-circuit gases. See Rebreather diving.

Modifying gases during a dive

Modifying the gas list in your device is for emergency cases only. For example, due to unforeseen events, you might lose a gas mixture, in which case you could adjust to the situation by deleting that gas mixture from the gas list of Suunto EON Steel. This allows you to continue diving and get correct decompression information calculated by the dive computer.

In another case, if for some reason you run out of gas and need to use a gas mixture from a dive buddy, it is possible to adapt Suunto EON Steel to the situation by adding the new gas mixture to the list. Suunto EON Steel re-calculates decompression and shows the correct information.

NOTE:

This feature is not enabled by default, it must be activated and it creates an additional step to the gas menu during the dive. It is only available if multiple gases are selected for the dive mode.

To enable modifying gases, turn the feature on in the settings menu under Dive settings » Parameters » Modify gases.

When enabled, during a multi-gas dive, you can add a new gas as well as select an existing gas from the gas list to remove it.

NOTE:

You cannot modify or remove the gas currently in use (active gas).

When Modify gases is turned on, you can remove gases which are not in use from the gas list, add new gases to the list, and modify parameters (O₂, He, pO₂) of nonactive gases.

Isobaric counterdiffusion (ICD)

 

Isobaric counterdiffusion (ICD) occurs when different inert gases (such as nitrogen and helium) diffuse in different directions during a dive. In other words, one gas is being absorbed by the body while the other is being released. ICD is a risk when diving with trimix mixtures.

This may happen during a dive, for example, when trimix gas is switched to nitrox or light trimix. When the switch is made, helium and nitrogen rapidly diffuse in opposite directions. This produces a transient increase in total inert gas pressure which can lead to decompression sickness (DCS).

Currently there are no algorithms that can address ICD. Therefore, you need to take it into account when planning trimix dives.

You can use Suunto EON Steel to plan your trimix usage safely. Under the Gases menu, you can adjust oxygen (O₂) and helium (He) percentages to see the change in partial pressure of nitrogen (ppN2) and the partial pressure of helium (ppHe) values.

An increase in partial pressure is indicated by a positive number, and a decrease by a negative number. The changes in ppN2 and ppHe are displayed next to each gas mixture that you want to switch to. Maximum operating depth (MOD) of a breathing gas is the depth at which the partial pressure of oxygen (pO₂) of the gas mix exceeds a safe limit. You can define pO₂ limit for the gas.

An ICD warning is generated when:

1. Gas switch depth is greater than 10 m (33 ft).
2. Geometric mean of the partial pressure change of N2 and partial pressure change of He is bigger than 0.35 bar.

If these limits are exceeded with a gas switch, Suunto EON Steel indicates the risk of ICD as shown below:

In this example, the available gas mixtures for a deep trimix dive are:

• Trimix 15/55, MOD 76.7 m (pO₂ 1.3)
• Trimix 35/15, MOD 27.1 m (pO₂ 1.3)
• Trimix 50/10, MOD 22 m (pO₂ 1.6)
• Oxygen, MOD 6 m

Suunto EON Steel highlights the dangerous ICD condition when the gas mixture switches from 15/55 to 35/15 at a depth of 27.1 m.

If this gas switch is made, the change in ppN2 and ppHe are far beyond the safe limits.

One way to avoid the ICD risk is to increase helium content in the first decompression gas mixture (trimix 35/15) to get a 35/32 trimix mixture. Due to this change, the second decompression gas (trimix 50/10) needs more helium to avoid ICD risk. The second decompression gas mixture should be trimix 50/12. These modifications would keep the changes in partial pressure at a safe level and remove the danger of sudden ICD.

 

 

Gas time

 

Gas time refers to remaining air (gas) left with current gas mixture, measured in minutes. The time is based on tank pressure value and your current breathing rate.

Gas time is also highly dependent on your current depth. For example, all other factors being the same, including breathing rate, tank pressure and tank size, depth affects gas time as follows:

• At 10 m (33 ft, surrounding pressure 2 bar), gas time is 40 minutes.
• At 30 m (99 ft, surrounding pressure 4 bar), gas time is 20 minutes.
• At 70 m (230 ft, surrounding pressure 8 bar), gas time is 10 minutes.

Gas time information is visible in Air/Nitrox and Trimix dive modes by default. If you have not paired a Suunto Tank POD, the gas time field shows n/a. If you have paired a POD but there is no data being received, the field shows –. This may be because the POD is not in range, the tank is closed, or the POD battery is low.

NOTE:

Set tank size under the Gases menu to get the gas consumption and the gas time calculations right.

NOTE:

Gas time reading shows zero and turns red if tank pressure goes below 35 bar (500 psi).

 

 

Language and unit system

You can change the device language and unit system any time when you are not diving. Suunto EON Steel refreshes immediately to reflect the changes.

To set these values, see How to set language and unit.

 

 

Logbook

Dive logs can be found under Logs. They are listed by date and time, and each entry listing shows the max. depth and dive time of the log.

Dive log details and profile can be browsed by scrolling through the logs with the upper or the lower button and selecting a log with the middle button.

Each dive log contains data samples with fixed 10-second intervals. The dive profile includes a cursor for browsing the logged data, scrollable with upper and lower buttons. A blue line indicates depth, and a white line shows temperature. If you dive with Tank POD, tank pressure and gas consumption graphs become also visible.

The last page of the logbook contains further data. Press the middle button to find average depth, CNS percentage, and OTU value.

For more detailed log analyses, upload the dive(s) to the Suunto app.

When the logbook memory gets full, the oldest dives are deleted to make space for new ones.

NOTE:

If you surface and then dive again within five minutes, Suunto EON Steel counts it as one dive.

 

 

Oxygen calculations

 

During a dive, Suunto EON Steel calculates partial pressure of oxygen (pO₂), central nervous system toxicity (CNS%) and pulmonary oxygen toxicity, tracked by OTU (oxygen toxicity units). The oxygen calculations are based on currently accepted exposure time limit tables and principles.

By default, in Air/Nitrox dive mode, CNS% and OTU values are not displayed until they reach 80% of their recommended limits. When either value reaches 80%, EON Steel notifies you and the value stays in the view. In default Trimix mode, CNS% and OTU values are displayed on the screen as scrollable info.

NOTE:

You can customize views to always show CNS% and OTU.

 

 

Personal setting

 

Suunto Fused™ RGBM 2 algorithm provides 5 personal setting options (+2, +1, 0, -1, -2). These options refer to decompression models. +2 and +1 can be considered conservative, while -2 and -1 can be considered aggressive. 0 is the default setting and is neutral, for ideal conditions. Generally speaking, conservative means safer. In practice it means that a dive at a given depth is shorter due to the decompression obligation (the no decompression time is short).

Conservative also means that the time the diver needs to spend on decompression is longer. For recreational divers, a conservative model means less time in the water in order to avoid decompression requirements. For technical divers, however, conservative means more time in the water because of the longer decompression requirements imposed during ascent.

Aggressive models, on the other hand, increase the potential health risks of a dive. For recreational divers, an aggressive model allows more time at depth, but may significantly increase the risk of decompression sickness (DCS).

The default setting for the Suunto Fused™ RGBM and Fused™ RGBM 2 is to use a compromise (0 setting) between conservative and aggressive. With the personal setting, you can select gradually more conservative or more aggressive calculations.

There are several risk factors that can affect your susceptibility to DCS like your personal health and behavior. Such risk factors vary between divers, as well as from one day to another.

The personal risk factors which tend to increase the possibility of DCS include:

• exposure to low temperature – water temperature less than 20 °C (68 °F)
• below average physical fitness level
• age, particularly over the age of 50
• fatigue (from over exercising, lack of sleep, exhausting travel)
• dehydration (affects circulation and may slow down off-gassing)
• stress
• tight fitting equipment (may slow down off-gassing)
• obesity (BMI that is considered obese)
• patent foramen ovale (PFO)
• exercise before or after dive
• strenuous activity during a dive (increases bloodflow and brings additional gas to tissues)

WARNING:

SET THE CORRECT PERSONAL SETTING! Whenever it is believed that risk factors that tend to increase the possibility of DCS exist, it is recommended that you use this option to make the calculations more conservative. Failure to select the correct personal setting will result in erroneous dive and planning data.

The five-step personal setting can be used to adjust the algorithm conservatism to fit your DCS susceptibility. You can find the setting under Dive settings » Parameters » Personal.

Personal level	Explanation
More aggressive (-2)	Ideal conditions, excellent physical fitness, highly experienced with a lot of dives in the near past
Aggressive (-1)	Ideal conditions, good physical fitness, well experienced with dives in the near past
Default (0)	Ideal conditions (default value)
Conservative (+1)	Some risk factors or conditions exist
More conservative (+2)	Several risk factors or conditions exist

WARNING:

Personal adjustment setting 0, -1 or -2 causes a high risk of DCS, or other personal injury, and death.

 

 

Rebreather diving

 

By default Suunto EON Steel has one mode dedicated to rebreather diving, CCR mode. This mode uses fixed high/low setpoint values which you can modify in the dive computer or through Suunto app.

Suunto recommends using classic or graphical style with rebreather diving. However, you can use prominent view and customize fields if desired.

Fixed setpoint calculation enables Suunto EON Steel to be used as a backup dive computer on rebreather dives. It does not control or monitor the rebreather unit in any way.

When you select your custom multi-gas mode for CCR (closed-circuit rebreather) diving in the dive mode setting, your device will have two different gas menus: CC gases (closed-circuit gases) and OC gases (open-circuit gases).

NOTE:

For rebreather dives, Suunto EON Steel should be used as a backup device only. The primary control and monitoring of your gases should be done through the rebreather itself.

Closed-circuit gases

 

On a rebreather dive, you need at minimum two closed-circuit gases: one is your pure oxygen tank, and the other is a diluent. You can define additional diluents as needed.

You can add only diluent(s) to the gas list. By default, Suunto EON Steel assumes that oxygen is used, so it is not shown in the gas list.

The correct oxygen and helium percentages of the diluent gases in your diluent cylinder(s) must always be entered into the dive computer (or through Suunto app) to ensure correct tissue and oxygen calculation. Diluent gases used on a rebreather dive are found under CC gases in the main menu.

Open-circuit gases

 

As with diluents, you must always define the correct oxygen and helium percentages of bailout gases for all your cylinders (and additional gases) to ensure correct tissue and oxygen calculation. Bailout gases for a rebreather dive are defined under OC gases in the main menu.

Setpoints

 

Your custom rebreather dive mode has two setpoint values, low and high. Both are configurable:

• Low setpoint: 0.4 – 0.9 (default: 0.7)
• High setpoint: 1.0 – 1.5 (default: 1.3)

Typically, you do not need to modify the default setpoint values. However, you can change them as needed either in Suunto app or under the main menu.

To change setpoint values in Suunto EON Steel:

1. While in surface state, keep middle button pressed to enter main menu.
2. Scroll to Setpoint with the upper button and select with the middle button.
3. Scroll to Low setpoint or High setpoint and select with the middle button.
4. Adjust the setpoint value with the lower or upper button and accept with the middle button.
5. Keep the middle button pressed to exit menu.

Setpoint switching

Setpoints can be switched automatically according to depth. By default, the low setpoint switch depth is 4.5 m (15 ft), and the high setpoint switch depth is 21 m (70 ft).

The auto setpoint switching is off by default for the low setpoint and on for the high setpoint.

To change auto setpoint switching in Suunto EON Steel:

1. While in surface state, keep middle button pressed to enter main menu.
2. Scroll to Setpoint with the upper button and select with the middle button.
3. Scroll to Switch low or Switch high and select with the middle button.
4. Adjust the depth value for the setpoint switch with the lower or upper button and accept with the middle button.
5. Keep the middle button pressed to exit menu.

Popup notifications indicate when the setpoint is switched.

During a rebreather dive, you can also switch to a custom setpoint at any time.

To change to a custom setpoint:

1. While diving in a rebreather mode, keep the middle button pressed to enter main menu.
2. Scroll to Custom setpoint and select with the middle button.
3. Adjust the setpoint value as needed with the lower or upper button and accept with the middle button.

A popup notification confirms the custom setpoint switch.

NOTE:

When you change to a custom setpoint, the automatic setpoint switching is turned off for the remainder of the dive.

Bailouts

 

If at any point during a rebreather dive you suspect a malfunction of any sort, you should switch to a bailout gas and abort the dive.

To change to a bailout gas:

1. Keep the middle button pressed to enter the main menu.
2. Scroll to OC gases and select with the middle button.
3. Scroll to the desired bailout gas and select with the middle button.

After a bailout gas is selected, the setpoint field is replaced with the pO₂ value of the selected open-circuit gas.

If the malfunction is rectified or the dive situation otherwise normalizes, you can switch back to a diluent using the same procedure as described above, but selecting from CC gases.

 

 

Safety stops and deepstops

 

Safety stop and deepstop ceilings are always at constant depth when you are at the stop. Safety stop and deepstop times are counted down in minutes and seconds.

Safety stop

There are two types of safety stops: voluntary and mandatory. Safety stop is mandatory if ascent speed violation happened during the dive. Mandatory safety stop is shown in red, while voluntary safety stop is indicated with yellow.

A three (3) minute safety stop is always recommended for every dive over 10 meters (33 ft).

The time for a safety stop is calculated when you are between 2.4 and 6 m (7.9 and 19.6 ft). This is presented with up/down arrows on the left side of the stop depth value. The safety stop time is shown in minutes and seconds. The time may exceed three (3) minutes if you ascend too fast during dive. If violations happened several times, the additional stop time is longer. Safety stops can be set to three (3), four (4), or five (5) minutes.

Voluntary safety stop is shown in yellow:

Mandatory safety stop is shown in red:

Deepstop

Deepstops activate only when you dive deeper than 20 m (66 ft). During ascend, deepstops activate when you are halfway up from your maximum depth. Deepstops are presented like safety stops. You are in the deepstop area when the deepstop depth has up/down arrows in front of it and deepstop time is running. The deepstop window is +/- 1.5 m (4.9 ft). Calculation starts at deepstop target depth plus 0.5 m (1.6 ft). Calculation ends - 3 m (- 9.8 ft) away from deepstop depth.

There can be more than one deepstop during ascend. For example, if you dive to 42 m (137.8 ft), the first deepstop is prompted at 21 m (68.9 ft) and the second is at 10.5 m (34.4 ft) The second deepstop is 2 minutes long.

In the following example the diver dives down to maximum 30.4 m (99.7 ft) and has a deepstop at 15.2 m (49.9 ft):

Below 20.0 m (66 ft), deepstop gets activated. In this case, as the diver ascends, the deepstop is necessary at halfway of the maximum depth, so at 15.2 m (49.9 ft).

If the deepstop depth is 15.2 m (49.9 ft), the calculation starts at 15.7 m (51.5 ft) and stops at 12.2 m (40.0 ft). The deepstop window is +/- 1.5 m (4.9 ft) and when the diver is within the deepstop window, it is indicated with two white arrows pointing at each other on the display.

When the diver ascends above the deepstop window ceiling - in this case above 14.2 m (46.6 ft) - a downward pointing yellow arrow signals that the depth is not optimal, it is recommended to descend. The deepstop target depth number also turns yellow.

If the diver keeps ascending, after 0.5 m (1.6 ft), a downward pointing red arrow and an alarm notifies the diver to descend immediately. The deepstop calculation keeps running for another 1.5 m (4.9 ft) up but stops after that. In the above example it stops at 12.2 m (40.0 ft).

NOTE:

For safety reasons, you cannot switch off deepstops if helium (trimix gas mixtures) is enabled for the dive mode in use. When helium is not in use, deepstops can be turned on and off. However, it is recommended that you turn deepstops on for all dives. If deepstops are turned on but omitted during a dive, it will affect your next dive which will be more conservative.

 

 

Sample rate

 

Suunto EON Steel uses a fixed sample rate of 10 seconds for all log recordings.

 

 

Standby and deep sleep

Standby and deep sleep are two functions that are designed to prolong battery life. Standby is an adjustable setting that turns off the screen after a set amount of time to save battery if Suunto EON Steel is not used.

To adjust the standby time:

1. Keep the middle button pressed to enter the menu.
2. Browse to General » Device settings » Standby.
3. Press the middle button to enter Standby.
4. Scroll up/down to select the desired standby time in minutes.
5. Press the middle button to save changes and return to the Device settings menu.
6. Keep the middle button pressed to exit.

Deep sleep

Deep sleep is a function that prolongs battery life when Suunto EON Steel has not been used for some time. Deep sleep is activated when two days have passed since:

• No buttons have been pressed
• Dive calculation has ended

Suunto EON Steel wakes up when it is connected to a PC/charger, when a button is pressed, or when the water contact gets wet.

 

 

Surface and no-fly time

After a dive, Suunto EON Steel displays surface time since the previous dive and a countdown time for the recommended no-fly time. During the no-fly time you should avoid flying or traveling to higher altitude.

No-fly time is the minimum surface time after a dive which is recommended to wait before flying with an airplane. It is always at least 12 hours. For desaturation times shorter than 75 minutes, no-fly time is not displayed. Maximum no-fly time is 72 hours.

If decompression is omitted during a dive and the dive algorithm is locked for 48 hours (see Algorithm lock), the no-fly time is always 48 hours. Similarly, if dive is done in gauge mode (bottom timer), the no-fly time is 48 hours.

With Suunto Fused™ RGBM 2, selected personal setting parameter (-2, -1, 0, +1, +2) is affecting no-fly time. The more conservative personal setting you have, the longer no-fly time values you will see. More aggressive personal setting will result in shorter no-fly time values.

Once the no-fly time calculated by your Suunto EON Steel with Suunto Fused™ RGBM 2 has ended, you can enter and fly with a normal airplane which is pressurized up to 3000 m.

WARNING:

YOU ARE ADVISED TO AVOID FLYING ANY TIME THE COMPUTER COUNTS DOWN THE NO-FLY TIME. ALWAYS ACTIVATE THE COMPUTER TO CHECK THE REMAINING NO-FLY TIME PRIOR TO FLYING! Flying or traveling to a higher altitude within the no-fly time can greatly increase the risk of DCS. Review the recommendations given by Divers Alert Network (DAN). There can never be a flying-after-diving rule that is guaranteed to completely prevent decompression sickness!

 

 

Suunto app

With the Suunto app, you can easily customize device and dive settings. See Customizing dive modes with Suunto app and How to customize dive modes with Suunto app.

You can also transfer your dive logs wirelessly to the app where you can follow and share your diving adventures.

To pair with Suunto app on iOS:

1. Download and install Suunto app on your compatible Apple device from the App Store. The app description includes the latest compatibility information.
2. Start Suunto app and turn on Bluetooth if it is not on already. Leave the app running in the foreground.
3. If you have not yet set up your Suunto EON Steel, do so now (see Device setup).
4. Tap the watch icon in the upper left corner of the screen and tap on the ' + ' icon to add a new device.
5. Select your dive computer from the list of found devices, tap PAIR.
6. Enter the passkey shown on your dive computer display into the pairing request field on your mobile device.
7. Tap PAIR at the bottom of the request field.

To pair with Suunto app on Android:

1. Download and install Suunto app on your compatible Android device from Google Play. The app description includes the latest compatibility information.
2. Start Suunto app and turn on Bluetooth if it is not on already. Leave the app running in the foreground.
3. If you have not yet set up your Suunto EON Steel, do so now (see Device setup).
4. Tap the watch icon in the upper right corner of the screen.
5. Select your dive computer from the list of found devices and tap PAIR.
6. Enter the passkey shown on your dive computer display into the pairing request field on your mobile device.
7. Tap PAIR at the bottom of the request field.

NOTE:

You cannot pair any device if airplane mode is on. Turn off airplane mode before pairing.

Synchronizing logs and settings

 

To be able to synchronize logs and settings, first you need to install Suunto app.

To download logs from your Suunto EON Steel and sync settings:

1. Connect Suunto EON Steel to your mobile device via Bluetooth.
2. Start Suunto app.
3. Wait for the syncing to complete.

New dive logs appear in your activity history, sorted by date and time.

 

 

SuuntoLink

Use SuuntoLink to update the software of your Suunto EON Steel. Download and install SuuntoLink on your PC or Mac.

We strongly recommend updating your device when a new software release is available. If an update is available, you are notified via SuuntoLink and in the Suunto app.

Visit www.suunto.com/SuuntoLink for further information.

To update your dive computer software:

1. Plug your Suunto EON Steel into the computer with the supplied USB cable.
2. Start SuuntoLink if it is not already running.
3. Click the update button in SuuntoLink.

TIP:

To sync your dives, connect the device to Suunto app before the software update.

 

 

Tank pressure

 

Your Suunto EON Steel can be used with the total number of twenty (20) gases per dive mode, each of which may have Suunto Tank POD for wireless tank pressure transmission.

To install and pair a Suunto Tank POD, see How to install and pair a Suunto Tank POD.

In tank pressure view you can see the below screens.

The following example has the tank pressure alarm set to 100 bars. The tank pressure is 75 bars as indicated in the switch window in the bottom right corner.

Tank pressure is shown in yellow when it is over 50 bars (720 psi) and below the tank pressure alarm value set by the user:

When the tank pressure drops below 50 bars (720 psi), the actual tank pressure value is indicated in red in the switch window and a mandatory alarm is triggered:

 

 

 

Timer

 

Suunto EON Steel has a timer that can be used for timing specific actions during surface or dive. The timer is shown in the bottom right corner as a scrollable item.

NOTE:

In timer view, the timer is displayed as an analog watch.

To use the timer:

1. Press the upper button to start the timer.
2. Press the upper button again to pause the timer.
3. Keep the upper button pressed to reset the timer.

Timer start and stop actions are saved in the dive log.

 

 

Water contacts

The water contact is located on the side of the case near the USB cable port. When submerged, the water contact poles are connected by the conductivity of the water.

Suunto EON Steel switches to dive state when water is detected. Dive starts

• when the water contact is on, at 1.2 m (4 ft), or
• when the water contact is not on, at 3.0 m (10 ft)

and ends

• when the water contact is on and your depth is less than 1.2 m (4 ft), or
• when the water contact is not on and your depth is at 3.0 m (10 ft).

When water contact is active, the color of the depth reading digits turns white.

 

 

Alarms, warnings, and notifications Algorithm lock Altitude diving Ascent rate Battery Bookmark Clock Compass Customizing dive modes with Suunto app Decompression algorithm Decompression dives Deco profile Device info Display Dive history Dive modes Dive planner Enriched Air Nitrox diving use Flip display Gas consumption Gas mixtures Gas time Language and unit system Logbook Oxygen calculations Personal setting Rebreather diving Safety stops and deepstops Sample rate Standby and deep sleep Surface and no-fly time Suunto app SuuntoLink Tank pressure Timer Water contacts

How to access device info

To access Suunto EON Steel information:

1. Keep the middle button pressed to enter the main menu.
2. Scroll to General with the upper or lower buttons and press the middle button.
3. Press the middle button to enter About EON.
4. Scroll to EON info, press the middle button to enter. You can check device software version, serial number, etc. there.
5. Scroll with the lower button to see all information.
6. Keep the middle button pressed to go back and exit from the menu.

How to change display brightness

To change brightness level:

1. Go to General » Device settings » Brightness.

2. Select from default, high, or low.

3. Turn the display brightness down to save battery life significantly.

   

How to set language and unit

To change the device language and unit system:

1. Go to Main menu » General » Device settings » Language and select your language.

2. Go to Main menu » General » Device settings » Units & formats.

   

3. Select Date format, Units, or Time format.

4. Use the upper or lower button to select from the available formats.

   NOTE:

   Under unit settings, you have the option of selecting metric or imperial as a global setting: it will affect all measurements.

5. To set the unit system for specific measurements, select Advanced. For example, you can use metric for depth, and imperial for tank pressure.

How to set language and unit

To change time and date:

1. Keep the middle button pressed to enter menu.
2. Browse to General » Device settings » Time & date.
3. Scroll to Set time or Set date with the upper or lower button.
4. Press the middle button to enter the setting.
5. Adjust the setting with the upper or lower button.
6. Press the middle button to move to the next setting.
7. Press again the middle button when last value is set to save and go back to Time & date menu.
8. Keep middle button pressed to exit when done.

To change time and date formats:

1. Keep the middle button pressed to enter menu.
2. Browse to General » Device settings » Units & formats.
3. Scroll to Time format or Date format with the upper or lower button.
4. Follow steps 5-8 as above to change and save formats.

How to install and pair a Suunto Tank POD

To install and pair a Suunto Tank POD:

1. Install the Tank POD as described in the Tank POD quick guide or in the Tank POD user guide.
2. After installing the Tank POD and opening the valve, wait for the green LED on the Tank POD to flash.
3. If your Suunto EON Steel has a blank screen, press any key to activate it.
4. Use proximity pairing: Hold your Suunto EON Steel close to the Tank POD. Make sure you follow the instructions in Tank POD alignment section of the Tank POD user guide.

5. After a few seconds, a menu pops up on the screen showing the Tank POD serial number, battery status and the tank pressure. Select the correct gas from the list to pair with your device and press the middle button to confirm pairing.

   

6. Repeat the procedure above for additional Tank PODs and select different gases for each POD.

Alternatively, you can pair the Suunto Tank POD(s) from the menu:

1. In the Gases menu, select the gas you want your Tank POD to pair with.

   

2. Press the middle button to open the gas settings and select Tank POD.

   

3. From the list of Tank PODs, select the one which matches the serial number of your Tank POD.

   

4. Make sure the Tank POD has been activated by ensuring the tank pressure reading shows on screen and POD green led is blinking.

   

In the dive main views, only one tank pressure is shown and corresponds to the active gas. When you change gas, the displayed tank pressure changes accordingly.

To unpair and remove your Tank POD from a specific gas using proximity:

1. Hold your Tank POD close to your dive computer in tank pressure view:

   

2. Gases menu opens. Select the gas you want to unpair your Tank POD from:

   

3. Select Unpair:

   

4. Your Tank POD is removed from the selected gas list:

   

   

To unpair and remove your Tank POD from a specific gas through the menu:

1. Select the gas you want to unpair the Tank POD from in the Gases menu:

   

2. Press the middle button to enter the gas settings and select Tank POD.

   

3. Select the Tank POD you want to unpair (check the serial number):

   

4. Select Unpair:

   

5. Your Tank POD is removed from the selected gas list:

   

   

How to plan a dive using the Dive planner

Before planning your first dive, go through the planner settings and configure them according to your personal preference. Access the planner and adjust settings under Main menu » Dive planner.

1. First set the values for:

   • personal gas consumption (default value: 25 L/min / 0.90 ft³)
   • tank pressure (default value: 200 bar / 3000 psi)
   • tank size (default value: 12 liters / 80 ft³, 3000 psi)
   NOTE:

   It is important to adjust these values first to get the gas calculations right.

2. Use the lower or upper buttons to decrease or increase the values. If you are not sure what your personal gas consumption is, we recommend using the default value of 25 L/min (0.90 ft³/min).

   NOTE:

   Estimated gas time is calculated based on tank pressure at start minus 35 bar (510 psi).

You can adjust dive depth, dive gas O₂ percentage and surface time interval in View planner.

Based on these parameters, Dive planner shows no decompression dive time for your planning purposes. If tank size, tank pressure and gas consumption are filled, planner shows gas time calculation too.

The calculated no decompression time is based on dive depth and gas mixture. Any residual nitrogen from previous dives, as well as surface time, is taken into consideration. Gas time is dependent on the dive depth, gas mixture, personal consumption, tank size and tank pressure.

Planning the first dive in a series

1. Edit depth and mixture in View planner.

2. As an example, enter 18 meters, use compressed air as a gas mixture, and you will see the following:

   

   In this example, the calculated values are:

   1. Dive number in the dive series: 1
   2. Available no decompression time: 51 minutes
   3. Remaining gas time: 41 minutes

Planning additional dives

The dive planner allows you to adjust surface time in 10-minute increments. 48:00 hours is the maximum value to be set.

In the example below, the surface time before the second dive is 1 hour 37 minutes. Adjust surface time to see how it impacts no decompression time.

How to customize dive modes with Suunto app

To customize Suunto EON Steel:

1. Download and install Suunto app from the app store of your iOS/Android mobile device.
2. Turn on Bluetooth on your phone and let the app find the available Suunto devices.
3. Pair your Suunto EON Steel with the app.
4. Select Dive mode customization. You can create new dive modes and modify existing ones.

Dive mode customization includes the following steps:

Customizing dive mode name

• Add your custom dive mode name. The maximum length of the name is 15 characters.
• Use something short and simple that helps you identify the features and information that you have customized in this mode.

Selecting dive type

• Select Gauge, CCR or OC type.
• For more information, see the detailed dive mode descriptions under Dive modes.

Selecting settings

• Set the settings which you need for your dive (e.g., stops, alarms).
• Note that setting options are available depending on the selected dive type.
• See the respective sections of the user guide for more information on each setting.

Customizing views

• Create up to four custom views for each dive mode.
• Select a new view from the list of stored views. No deco (Default), Compass, Tank pressure and Timer views are available for you.

• Customize the style of the view. Select prominent, graphical or classic style:

  • Prominent style presents key information with large numbers:

    

  • Graphical style presents information with additional visual elements:

    

  • With classic, information is presented in the traditional manner using numbers:

    

• Modify, delete or add new customizable fields within each view.

• For more information about the views in different dive modes, see the respective sections under Dive modes.

Adding and editing gases

• Configure what you see under the Gases menu in your Suunto EON Steel device.
• Turn Multiple gases on or off.
• When Multiple gases is on, add new gases.

Technical specifications

Dimensions and weight:

• Length: 104.6 mm / 4.12 in
• Width: 60.5 mm / 2.38 in
• Height: 23.1 mm / 0.91 in
• Weight: 347 g / 12.2 oz

Operating conditions

• Normal altitude range: 0 to 3000 m / 9800 ft above sea level
• Operating temperature: 0 °C to +40 °C / +32 °F to +104 °F
• Storage temperature: -20 °C to +50 °C / -4 °F to +122 °F
• Recommended charging temperature: 0 °C to +35 °C / +32 °F to +95 °F
• Maintenance cycle: 500 hours of diving or two years, whichever comes first

Depth gauge

• Temperature compensated pressure sensor
• Maximum depth of operation: 80 m / 262 ft (complying with EN 13319)
• Maximum static pressure: 15 bar (complying with EN 13319 and ISO 6425)
• Accuracy: ± 1% of full scale or better from 0 to 150 m / 492 ft at 20 °C / 68 °F (complying with EN 13319)
• Depth display range: 0 to 300 m / 984 ft
• Resolution: 0.1 m from 0 to 100 m / 1 ft from 0 to 328 ft; 1 m from 100 to 150 m / 1 ft from 328 to 392 ft

Temperature display

• Resolution: 1 °C / 1.5 °F
• Display range: -20 °C to +50 °C / -4 °F to +122 °F
• Accuracy: ± 2 °C / ± 3.6 °F within 20 minutes of temperature change in temperature range of 0 °C to +40 °C / +32 °F to +104 °F

Displays in mixed gas dive mode

• Helium %: 0–95
• Oxygen %: 5–99
• Oxygen partial pressure display: 0.0–3.0 bar
• CNS%: 0–500% with 1% resolution
• OTU: 0–1000

Other displays

• Dive time: 0 to 999 min
• Surface time: 0 to 99 h 59 min
• Dive counter: 0 to 99 for repetitive dives
• No decompression time: 0 to 99 min (>99 above 99)
• Ascent time: 0 to 999 min (>999 after 999)
• Ceiling depths: 3.0 to 300 m / 10 to 984 ft

Calendar clock

• Accuracy: ± 25 s/month (at 20 °C / 68 °F)
• 12/24 h display

Compass

• Accuracy: ± 15°
• Resolution: 1°
• Max. tilt: 45 degrees
• Balance: global

Timer

• Accuracy: 1 second
• Display range: 0’00–99’59
• Resolution: 1 second

Logbook

• Sample rate: 10 seconds
• Memory capacity: approximately 200 hours of diving or 400 dive logs, whichever comes first

Tissue calculation model

• Suunto Fused™ RGBM 2 algorithm (developed by Suunto and Bruce R. Wienke, BSc, MSc, PhD)
• 15 tissue compartments
• Tissue compartment halftimes for nitrogen: 1, 2, 5, 10, 20, 40, 80, 120, 160, 240, 320, 400, 480, 560 and 720 min. The on-gassing and off-gassing halftimes are the same.
• Tissue compartment halftimes are divided by a constant factor to obtain helium halftimes.
• Reduced gradient (variable) M-values based on diving habit and dive violations. The M-values are tracked up to 100 hours after a dive
• The exposure calculations (CNS% and OTU) are based on recommendations by R.W. Hamilton, PhD and currently accepted exposure time limit tables and principles.

Battery

• Type: 3.7 V rechargeable lithium-ion
• Charging: USB: 5 Vdc, 0.8 A
• Battery life: fully charged, min. 20 h dive time

The following conditions have an effect on the expected battery lifetime:

• The conditions in which the unit is operated and stored (for example, temperature/cold conditions). Below 10 °C / 50 °F the expected battery lifetime is about 50–75% of that at 20 °C / 68 °F.
• The quality of the battery. Some lithium batteries may exhaust unexpectedly, which cannot be tested in advance.

Radio transreceiver

• Bluetooth® Smart compatible
• Frequency band: 2402–2480 MHz
• Maximum output power: <4 dBm
• Range: ~3 m / 9.8 ft

Underwater radio receiver

• Frequency band: single channel 123 kHz
• Range: 1.5 m / 4.9 ft

Manufacturer

Suunto Oy

Tammiston kauppatie 7 A

FI-01510 Vantaa FINLAND

Compliance

For compliance related information, see “Product Safety and Regulatory Information” delivered together with your Suunto EON Steel or available at www.suunto.com/SuuntoEonSteelSafety.

Trademark

Suunto EON Steel, its logos, and other Suunto brand trademarks and made names are registered or unregistered trademarks of Suunto Oy. All rights are reserved.

Patent notice

This product is protected by pending patent applications and their corresponding national rights: US 13/803,795, US 13/832,081, US 13/833,054, US 14/040,808, US 7,349,805, and US 86608266.

Additional patent applications may be filed.

International Limited Warranty

Suunto warrants that during the Warranty Period Suunto or a Suunto Authorized Service Center (hereinafter Service Center) will, at its sole discretion, remedy defects in materials or workmanship free of charge either by a) repairing, or b) replacing, or c) refunding, subject to the terms and conditions of this International Limited Warranty. This International Limited Warranty is valid and enforceable regardless of the country of purchase. The International Limited Warranty does not affect your legal rights, granted under mandatory national law applicable to the sale of consumer goods.

Warranty Period

The International Limited Warranty Period starts at the date of original retail purchase.

The Warranty Period is two (2) years for Watches, Smart Watches, Dive Computers, Heart Rate Transmitters, Dive Transmitters, Dive Mechanical Instruments, and Mechanical Precision Instruments unless otherwise specified.

The Warranty Period is one (1) year for accessories including but not limited to Suunto chest straps, watch straps, chargers, cables, rechargeable batteries, bracelets and hoses.

The Warranty Period is five (5) years for failures attributable to the depth measurement (pressure) sensor on Suunto Dive Computers.

Exclusions and Limitations

This International Limited Warranty does not cover:

1. 1. normal wear and tear such as scratches, abrasions, or alteration of the color and/or material of non-metallic straps, b) defects caused by rough handling, or c) defects or damage resulting from use contrary to intended or recommended use, improper care, negligence, and accidents such as dropping or crushing;
2. printed materials and packaging;
3. defects or alleged defects caused by use with any product, accessory, software and/or service not manufactured or supplied by Suunto;
4. non-rechargeable batteries.

Suunto does not warrant that the operation of the Product or accessory will be uninterrupted or error free, or that the Product or accessory will work with any hardware or software provided by a third party.

This International Limited Warranty is not enforceable if the Product or accessory:

1. has been opened beyond intended use;
2. has been repaired using unauthorized spare parts; modified or repaired by unauthorized Service Center;
3. serial number has been removed, altered or made illegible in any way, as determined at the sole discretion of Suunto; or
4. has been exposed to chemicals including but not limited to sunscreen and mosquito repellents.

Access to Suunto warranty service

You must provide proof of purchase to access Suunto warranty service. You must also register your product online at www.suunto.com/register to receive international warranty services globally. For instructions on how to obtain warranty service, visit www.suunto.com/warranty, contact your local Suunto retailer, or contact Suunto support at www.suunto.com/support.

Limitation of Liability

To the maximum extent permitted by applicable mandatory laws, this International Limited Warranty is your sole and exclusive remedy and is in lieu of all other warranties, expressed or implied. Suunto shall not be liable for special, incidental, punitive or consequential damages, including but not limited to loss of anticipated benefits, loss of data, loss of use, cost of capital, cost of any substitute equipment or facilities, claims of third parties, damage to property resulting from the purchase or use of the item or arising from breach of the warranty, breach of contract, negligence, strict tort, or any legal or equitable theory, even if Suunto knew of the likelihood of such damages. Suunto shall not be liable for delay in rendering warranty service.

Dive terms