Not sure they would work under a float in the traditional Float set up. You could bobber dog them. A good friend of mine has told me they can be very effective drift fishing them as well, especially on silvers.

They really need to have some current or water flow over them in order to impart their action. Hanging under a float would not really allow that I don't believe.

That's my very limited 2 cents, perhaps some of the more experienced guys can elaborate...