ORIGINAL: Alsatian
SwampCollie: So, are the vibrators anchored so they are submerged UNDER the water and hence out of sight of the ducks or do they float on top of the water, in plain view of the ducks, but not off-putting for the ducks?
Sorry I didn't see your counter question til now.
They float about dead even with the water surface. The flat top of the shaker is about flush with the water. They don't scare the ducks though. They are painted that nice neutral color. Ducks can't tell exactly where the ripples come from... just that the surface isn't stagnant still. In the timber we always just used our foot to kick the water up... that or a paddle churned sideways works well too.