How boat traveller's stay duration is tracked in USA?
I came to the USA by the plane and got 180 days to stay(B1/B2 visa). Then I was travelling exactly 180 days around the USA on the sailboat. And left the country from Key West to Cuba on the sailboat. I didn't inform anybody I'm leaving the country.
In this question I see the difficulties that can happen due to an overstay. As I understand, airlines inform the US government.
How stay duration is tracked in my case?
Update 1: @Crazydre gave a good explanation what to do if something wrong. Thanks, this is very useful. But my question was: How stay duration is tracked for such cases?
Update 2: This question is purely theoretical as I entered to USA 4 times after this. But before each entrance I wondered and worried about how my staying was tracked.
Pictures about "How boat traveller's stay duration is tracked in USA?"
Sailaway Tutorial #8 - Main Traveller
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Aleksandar Pasaric, Max Avans, Jill Evans, Yoss Traore