* Current capacity limited by anode mass and self consumption at low current density.
* Lower driving voltage means the anodes may not work in high-resistivity environments.
* Often requires that the protected structure be electrically isolated from other structures and ground.
* Anodes are heavy and will increase water resistance on moving structures or pipe interiors.
* Where D.C. power is available, electrical energy can be obtained more cheaply than by galvanic anodes.
* Where large arrays are used, wiring is needed due to high current flow and need to keep resistance losses low.
* Anodes must be carefully placed to avoid interfering with water flow into the propeller.
* To retain effectiveness, the anodes must be inspected and/or replaced as part of normal maintenance.