OLD NEW STOCK. Cathodic Protection Control with Monitoring. Automatic Control Maintains Constant Protection Level - for vessels up to 45 feet LOA. These controlled sacrificial anode systems provide complete protection against galvanic corrosion on fiberglass and wood hulled boats. Monitoring allows a visual indication of system performance and early warning of stray corrosion currents from electrical faults. Caustic attack to wood at protected fittings is prevented.