wojo: The ones I like best have two aluminum adjustable flag pole mounts, so you can adjust the amount of depth of the floats. I considered making a pair for my skiff, using four 8" foam trap float buoys, two back to back, per side. There's a fisherman's supply in Alabama(I think), that sells them for $10 each. Good luck!
I'm an Eighth Day Adventist. On the Eighth Day, God went fishing!