I would hire a developer

[PaddyB]

So, here it goes: "watch commander"

in case of long offshore passages, the person on the helm normally takes about 10 minutes intervals between the horizon/route check. It practically means a 10 minute nap between every 360 visual check.
The watch commander can be set to a time interval, after which it activates a buzzer. If the buzzer is muted by a button within 15 sec, the countdown starts again. If not, a much louder alarm is activated to wake up everybody aboard as the person at the helm may fall overboard or other issues preventing him/her to mute the buzzer.

Such a watch commander is a great safety feature - currently priced quite high (USD 200+) - it could be another feature which sets open cpn apart from all other chartplotter.

Opencpn has similar in the watchdog plugin. No activity for X minutes sound an alarm and/or run a command >