I do have an old tarp and a few sections of pvc pipe in the garage - might see what I can come up with
In my reading on this subject - ancient mariners would just let out a long length of rope to help steady a ship - or if conditions got real bad, they would tie blankets and other stuff to the rope.
But this tarp set up looks like more fun to make.
I wonder if silicone, hot glue, sewing or a combination, would be the best to seal the seams on one made from a tarp