Updating firmware on NMEA 2000 devices should be done in a safe, low-risk window with stable power and minimal risk of disrupting navigation. The reason updating during critical navigation is inappropriate is that the process can cause a device to reboot or pause while it installs the new software. During that reboot, the device may stop transmitting its PGNs or momentarily fail to communicate on the bus, which can disrupt other connected devices and real-time navigation functions such as GPS, autopilot, or sensors. Since the NMEA 2000 network relies on timely, continuous data exchange, any interruption can compromise situational awareness and safe operation. That's why you want to perform updates when the boat is not actively navigating or in a high-stakes mode, ensure power is stable, and the bus has enough headroom to handle the update without drops. After the update, verify the device to confirm it’s functioning correctly and re-check bus stability. Using the manufacturer’s tools to carry out the update and verifying the device afterward are good practices that help ensure the update goes smoothly and the network remains reliable.