 As divers are seldom weighted to be very negatively buoyant, a positive buoyancy of 50 kg is considered adequate by some authorities for general commercial use.Recreational divers are free to choose lesser buoyancy at their own risk.The shot weight should be sufficient to prevent a diver from lifting it from the bottom by over-inflation of the buoyancy compensator or dry suit, but not sufficient to sink the float if the slack on the line is all taken up.