This is the most complex advice I have ever seen on curtains in my life!
Curtains are rectangular pieces of fabric
For a boat, sew 2" hem on top & bottom so you can run a curtain rod through both. Our boat has rows of windows in the cabin
similar to most boats.
Previous owner hung 1 curtain rod above the windows and 1 below.
Owners wife sewed the curtains (see above). They stay on the rods, don't flop around, open & close without a bunch of drama or extra parts
, and you can take them off & wash them if they get funky.
This is an easy sewing project
for beginning sewer (perfect first project
on a borrowed sewing machine) and piece of cake for intermediate / advanced sewer (i.e. CHEAP
if you have to hire or barter it done)
Good luck & happy sewing.