Shearwater TERN

The Shearwater Tern and Tern TX is an advanced, user-friendly dive computer designed for divers who demand simplicity without compromising on performance. Featuring a large 1.3-inch AMOLED color screen with 360 x 360 resolution, the Tern offers exceptional readability, whether you're exploring shallow reefs or deep dives.

The Tern includes versatile open-circuit dive modes for Air, single-gas Nitrox (up to 40%), and 3-gas Advanced Nitrox (up to 100% O2), making it perfect for recreational and free divers. It also features a comprehensive gauge mode for those who prefer a more basic tracking system for their dives.

The Tern TX version adds advanced features, including a built-in digital compass for enhanced navigation and cylinder gas pressure integration (AI) with support for up to four optional SWIFT wireless transmitters (sold separately). This feature allows you to monitor tank pressure directly from the dive computer, giving you better awareness and control during your dive.

Feature Highlights:

• Air/Nitrox Capability: Supports up to 100% O2 for flexible gas choices.
• 3 Gas Switch Presets: Easily switch between up to three open-circuit gases.
• Bühlmann ZHL-16C Algorithm: Includes configurable Gradient Factors (GF) for personalized dive planning.
• Preset Gradient Factors: Choose from High (35/75), Medium (40/85), Low (45/95), or set your own GF for sport diving No Decompression Limits (NDL).
• Multi-Compartment Tissue Saturation Bar Graphs: Real-time monitoring of tissue saturation for accurate decompression management.
• %CNS Oxygen Exposure Tracking: Tracks cumulative oxygen exposure to ensure safe diving practices.
• No Decompression Limit (NDL) Sport Dive Planner: Plan your dives with real-time NDL calculations and safety.
• Ascent Rate Monitor: Keeps track of ascent rates to ensure safe and controlled ascents.
• Haptic (Vibration) Alarm: Alerts you with vibration for critical dive information. Can be disabled.
• Date, Time, and Temperature Display: Always know your dive time, surface time, and water temperature.
• Ergonomic Two-Button Operation: Intuitive interface with adaptive menus, available in 10 languages.
• Customizable Home Screen: Personalize your display to show the most relevant dive data.
• Units: Select between imperial (feet) or metric (meters) units.
• 500-Hour Logbook: Record up to 500 hours of dive data for easy reference.
• Battery Charge Indicator: Always know your remaining battery life with a visible charge warning.
• TX Model Features: Includes digital compass and supports optional wireless tank pressure transmitters for air integration.

The Tern is equipped with a wireless rechargeable battery and comes with an induction charging pad for easy charging. On a full charge, you can expect up to 20 hours of dive time at medium screen brightness. While Shearwater recommends using their dedicated charging pad, the Tern is also compatible with Qi wireless-charging mats, including those used with the latest iPhones and many Android phones.

The Tern's software includes a comprehensive dive log manager that is compatible with both Windows and Mac OS X. It can be downloaded directly from Shearwater’s website, along with the user manual. The dive log manager allows you to download dive logs and perform firmware updates via Bluetooth. Optional accessories available separately include wrist strap kits in ocean blue, white, and black as well as additional charging mats.

For advanced diving needs, the Tern features a 3-gas mode with a full suite of decompression tools for extended-range dives. During a decompression dive, the Tern provides detailed stop times, and supports user-configurable Gradient Factors and "look-ahead" gas switching for precise planning and time-to-surface calculations. The Tern is designed to never lock out after a missed stop or ascent rate violation, offering full dive flexibility. It also supports 100% oxygen for accelerated decompression with a configurable deco PO2 setting, and allows you to select the final stop depth (either 10 ft | 3 m or 20 ft | 6 m).

Additional warnings include prompts to switch gases upon reaching your optimal PO2 setting, along with ascent rate indicators and stop approach notices. The real-time multi-compartment tissue saturation bar graph remains visible, allowing you to track tissue off-gassing during extended deco stops without needing to toggle back and forth. For table divers, the Tern also includes a fully-featured gauge mode that is operational to at least 394 ft | 120 m.

Sport Nitrox Mode Features:

For sport divers who don’t need extended range features, the Tern offers an intuitive and user-friendly experience. Key features of the Sport Nitrox mode include:

• A simplified menu structure for easy navigation
• A less cluttered display with configurable bottom-row data
• Optional safety stops (user-adjustable to 3, 4, or 5 minutes, or adaptable settings)
• A No Decompression Limit (NDL) dive planner for clear and safe dive planning

The Tern clearly warns the diver if their depth is approaching or exceeding the Maximum Operating Depth (MOD) of the selected breathing gas. When using the Adapt setting, a 3-minute safety stop will be used unless the dive exceeds 100 ft | 30 m or the NDL is below 5 minutes, in which case a 5-minute safety stop is applied. If the diver exceeds the NDL and requires decompression, the Tern displays a red warning and prompts with required depths and stop times.

Modes

• Air
• Nitrox
• 3 Gas Nitrox
• Gauge
• Freediving