Yes, it's not so much that it wouldn't work as that other approaches would often work better. If fuel is scarce than maybe a solar still.

Maybe something like, 2 transparent plastic bottles with a pipe between them. Put a little sea water in one and hope some if it condenses in the other. You could speed up condensation by putting the empty bottle in the shade and in cool water, eg hanging over the side of the boat. You could speed up evaporation by letting the sea-water bottle get hot, eg by putting it in the sun and on something black.Cloudy water might do better than clear.