It depends on the plane but it doesn't take much. If the water is not
glassy the landing can be very short. Both takeoffs and landings can
require more space if the water is glassy but you could always choose
to not fly at those times or just ensure you have enough space. Is
this body of water somewhat clear or do you have a lot of things
floating in it (logs, etc)?

-Robert, CFII (land and sea)


Robert,

Out of my pure ignorance, what does glassy water have to do with
TO/Landing distance? I have been searching on the internet trying to
find something educational, but not having much luck.

I would think the Landing would be longer because the lack of ripples
would result in less resistance in the water, but I would think the TO
would be shorter for the same reason. What am I missing?

Mike