the environment used the preparation of the composition is relatively straight forward the required amount of anode material is added to the carrier material and the resulting admixture is agitated until homogeneous the subsurface container for the anode containing composition should contain perforations in order to allow the water access to the sacrificial anodes the size of the subsurface container is not critical it can be fabricated of steel metal suitable plastics or fiberglass a preferred material for preparing the container is an epoxy fiberglass composite molding the container can be supported by a number of suitable means such as clamps or rods attached to the platform as stated hereinbefore a tubing is used to convey the anode containing composition from the container on the deck to the subsurface container the tubing can be made of metal or plastic one advantage of our invention is that small diameter tubing can be used steel is a particularly suitable material for the tubing a multiplicity of conduits and subsurface containers can be provided on the steel platform in order to protect the entire structure the number of these can be readily determined by those skilled in the art also the means of locating them on the platform can be readily determined if necessary a separate electrical connection is provided between the underwater apparatus and the offshore platform in other words if the tubing subsurface container and support members are made of non conductors a separate electrical connection must be provided as is implied throughout our apparatus does not have an impressed current the voltage and current are provided by the potential difference of the metal in the platform and the sacrificial anode metal our apparatus uses a.