The triple-expanding spray foam sold in most home-improvement stores can be used to provide flotation for your non-floating gaffs, tag sticks and boat hooks that have hollow handles. All you will need is a can of foam and about ten feet of aquarium air hose or similar hose that fits over the screw-in application tube that comes with the foam. Attach the hose to the application tube on the can of foam. Drill a 1/4" hole at one end of the handle, then slip the aquarium tubing completely into the handle through the hole you drilled. Begin spraying the foam, making certain to let the foam work its way to the end of the hose before you begin to withdraw it. With a steady pull, withdraw the aquarium tubing as you spray the foam, filling the entire handle. Excess foam will ooze out the hole when you finish, but you can simply snap off the excess when it dries.