The Engine 

The 41mm Steel Navigator (SSNAV) and the 41mm Steel Navigator w/ Date (SSNAV-D) have received many engineering improvements when compared to the design of their predecessor. One of the biggest updates is in the form of the new quartz movement: the 3 Jewel ETA F06.412 with HeavyDrive-PreciDrive. 

Now the most precise timepieces in the Marathon electric watch lineup, the Steel Navigator Series features an accuracy of ± 10s/year, operating at 32’768 Hz. This is made possible by the combination of ETA’s venerable quartz technology, as well as customizations specifically for Marathon.

Shock Protection 

Marathon has improved the shock protection of the Steel Navigator by improving both the movement as well as the protective cage surrounding it. 

Housed within this particular movement is ETA’s HeavyDrive technology, offering shock detection and management by way of an integrated circuit. When a shock is detected, the motor applies a counter force to prevent the hand from skipping and affecting the accuracy of the movement. 

Further stabilizing the movement is Marathon’s fully revised movement mounting system. Inside the Steel Navigator is a steel ring that secures the F06.412 in place with three screws. This is engineered to protect the movement against unwelcomed forces such as torque, vibration, and impact. 

Temperature & Humidity Protection 

The Marathon Steel Navigator also features ETA’s PreciDrive technology.  This technology consists of a thermo-compensation unit that monitors and reacts to changes in the watch’s internal temperature as well as the temperature of the surrounding environment. The thermo-compensation unit of the F06.412 is sealed in a vacuum-insulated, brass-plated housing.  

These features, in combination with Marathon’s addition of a screw-down crown and improved water-tight gasket system, allow the movement to be unaffected by humidity. 

Battery Life 

With the F06.412 generating a longer battery life – approximately 86 to 94 months – the watch poses benefits to the environment and consumers alike. Less batteries equals less waste, plus reduced hassle for users with fewer battery replacements over the watch’s lifetime.  

All F06 movements have a built-in EOL (End of Life) Indicator that will notify the user to change the battery within 3 months of the battery expiring. You’ll note that the secondhand will begin ticking in a pulsed, four second interval pattern. The watch will continue to display the correct time until the battery is fully depleted, however the visual effect will alert the user to the need of a battery change with time to spare. 

Another update to the internal design of the Steel Navigator is Marathon’s new battery hatch spring. In the past, models have featured a standard spring - a small piece of metal with prongs that sits in between the battery hatch and the battery itself. In this new version, the spring is mounted to the inside of the battery hatch cover, preventing the spring from being misaligned or lost during battery change. 

Date Complication 

A first for any Steel Navigator, the new SSNAV-D model includes a date function. Historically the Steel Navigator was produced solely for government contracts and only with a no-date dial, as a date display version was never specifically required. This feature was introduced due to the popularity of the current composite 41mm Pilot’s Navigator with Date, as well as the understanding that modern pilots require a date display especially when preparing reports in the field.