The Tern from Shearwater is an Advanced Nitrox dive computer with easy-to-understand menus. The Tern offers a large { 1.3 in | 3.3 cm } easy-to-read display utilizing a AMOLED 360 x 360 color screen. The Tern includes open-circuit dive modes for Air, single gas Nitrox (up to 40%), and user selectable 3-gas Advanced Nitrox (up to 100% O2), as well as a richly featured gauge and freedive modes.

Feature Highlights

• Air/Nitrox capable up to 100% O2
• 3 open-circuit gas switch presets
• Bühlmann ZHL-16C algorithm with configurable Gradient Factors
• GF presets for sport diving NDL safety factor: High = 35/75, Medium = 40/85, Low = 45/95, plus user defined GF
• Multi-compartment tissue saturation bar graphs
• %CNS oxygen exposure tracking
• No decompression limit (NDL) sport dive planner
• Ascent rate monitor
• Haptic (vibration) alarm that can be disabled
• Date, time and temp display
• Easy ergonomic operation adaptive menus with support for ten languages
• Extensive "home screen" customization options
• User configurable units: imperial (feet) or metric (meters)
• Logbook of last 400 hours of diving
• Battery charge delivers 20 hours of diving (medium brightness) with 6 months in standby
• Battery charge level and warning
• TX model supports digital compass and optional wireless tank pressure transmitters

Also...

• Daily wear timepiece mode with a selection of watch faces
• Richly featured gauge mode to at least { 394 fsw | 120 msw }
• Easy-to-Read Large AMOLED full COLOR 360x360 screen
• Display brightness levels are user adjustable or auto compensating
• Screen Flip - wear on left or right wrist with buttons at top or bottom
• Compact case dimensions - { 2 in | 50 mm } x ( 0.63 in | 16 mm }
• 22 mm quick connect silicone wrist straps (one long and one short strap included)
• Bluetooth Smart wireless upload/download
• User upgradeable firmware
• Wireless rechargeable internal battery
• Shearwater Cloud Dive Log Software
• Two Year Limited Warranty

The Tern has been designed with a wireless rechargeable battery and includes a wireless induction charging pad. Typical dive time on a single charge is 20 hours at medium screen brightness. Although Shearwater recommends using their specific charging pad, the Tern can also be charged by the flat mats that support the Qi wireless-charging standard (which includes the latest iPhones and many Android phones).

What's in the box?

Included with every Tern from Trident Warriors are a polished stainless steel bezel and buttons, 22 mm black silicone quick connect three piece wrist strap kit with a polished stainless steel, zippered ballistic nylon polymer travel case, wireless charging pad and USB cable. The Tern also includes a PET screen protector already installed on the display. The software includes a complete dive log manager in both desktop and mobile app versions that can be downloaded from Shearwater's website along with the manual. The dive log manager supports log downloads and firmware updates via the Bluetooth wireless interface. Optional accessories available separately include color wrist strap kits, replacement PET screen protectors, and additional charging mats. Shearwater supplies the Tern with a very snug zippered "travel" case but if you want a well padded case suitable for boat use and with room for extra storage, consider adding the optional Padded Storage Bag.

Advanced Nitrox Mode Features

The Tern has a 3-gas advanced mode that includes a complete planned decompression feature set for extended range diving. During a decompression dive, the Tern provides complete information displays of all required stop times. It supports a user configurable Gradient Factor and "look ahead gas" switching (based on the gases defined and active) for the planner and time-to-surface calculations. The Tern will NOT "lockout" after a missed stop or ascent rate violation. The Tern also supports 100% oxygen for accelerated decompression with a user configurable deco PO2 setting. The last stop depth is user selectable as {10 fsw | 3 msw } or {20 fsw | 6 msw }. Warnings include prompts to switch gases upon reaching a user configurable optimal PO2 setting and a stop approach notice plus an ascent rate indicator. The real-time multi-compartment "tissue" saturation bar graph does not time out and thus allowing tissue off-gassing to be observed on an extended deco stop without having to cycle back to it repeatedly. For table divers needing a bottom timer, the Tern also offers a very richly featured gauge mode operational to at least { 394 fsw | 120 msw }.

Sport Nitrox Mode Features

Sport divers who don't need extended range features will find the Tern even more diver friendly! Key features of the Tern single gas Sport Nitrox mode include a simpler menu structure, less cluttered display and configurable bottom row, optional safety stops, and a no decompression limit (NDL) dive planner. The simplified settings allow for one breathing gas mixture (Air or Nitrox up to 40%) and places a greater emphasis on the maximum operating depth (MOD) and no decompression time limit. The display prominently warns the diver if their depth is near, at or exceeds the MOD of the selected breathing gas. Optional safety stops are user configurable to be 3, 4, 5 minutes or adaptable. When using the Adapt setting, a 3 minute safety stop will be used, unless the dive exceeds { 100ft | 30m } or the NDL falls below 5 minutes, in which case a 5 minute safety stop is used. If the diver exceeds the NDL and requires stops, the display turns red and warns "DECO STOP" with the mandatory depth and stop times.