You missed the story structure.
Story one, on the beach, was a week long.
Story two, on the boat, was a day long.
Story three, the air battle, was an hour long.
Which is why you can see the Dutch trawler sinking next to the minesweeper in one scene, and the soldiers climbing aboard the rounded trawler on the beach in the next, and why the bobing of the inesweeper is seen three times.
*grounded
=beached at high tide