When using a slip float, a bobber stop made of rubber or string is used to set the depth. Because you are able to wind the bobber stop through the line guides on your rod and onto the reel you can easily cast a float that is set for a much greater depth than you can with a fixed float. It is also very simple to adjust the depth you are fishing by merely sliding the bobber stop up and down the line. A properly adjusted slip float will also allow you to return to an exact depth once you have located fish. I have used floats to fish as shallow as 1 foot and as deep as 60 feet.
Floats can be a very valuable tool when fish seem wary, and a subtle presentation is necessary.
They are an excellent choice when you need to keep the bait suspended at a given depth for long periods of time to entice a strike. If we moved the boat close enough to present a lure vertically the fish became spooked and scattered. We positioned the boat on the opposite side of the channel. My partner rigged a jig below a float at a depth of less than 3 feet. I persisted in trying to present a free swimming jig by casting and retrieving.