How does a marina know how long you will be away?

[Laysula]

If we're staying out overnight I give the marina a call on the radio as I leave. Doubles up as a radio check as well.

 

[Boathook]

There are also cheekier peeps always arriving 5 minutes after the afternoon marina closing time and leaving 5 minutes earlier than the morning opening time, surprisingly with boats where the price of a shackle for their tender would buy them a week in a marina. I've seen quite a few, 99% flying the same flag (won't tell which, I suspect you'll have noticed the same).

A few years back, I arrived at Falmouth Yacht haven as the 'office' was shutting. Offered to pay but they said tomorrow will do. Said we were leaving early to catch tide and they said enjoy the free stay, so we did !
At least I tried to pay.