i agree with anon     that they're mimicking aircraft lights either for communication or to try to blend in my other theory is that whoever is piloting those has not developed advanced communication systems despite having advanced ships, maybe they don't have radar type systems think about it like this, it's the 1400s and you're in columbus 3 ships sailing across atlantic ocean, let's say the ships are 500 feet apart, you can't just call each other on the phone so they would use torches, lights, flares, flags whatever to transmit short range messages, i think its a similar thing here, light is the universal telephone
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