Your zinc is incapable of supplying enough galvanic potential to protect against substantial DC currents that may be flowing in the water. Your zinc is only intended to protect against the modest galvanic potentials and therefore currents that are caused by the dissimilar metals that are immersed and electrically connected together on your own boat. The anodic bit of metal or thru-hull that has the misfortune to be on the “out current” side of the current running through your bonding system will also become “out metal” and will disappear, sometimes rapidly. If your bits of immersed metal are bonded, the electric current will take the lower resistance path offered by your boat in preference to the water near your boat, and the current will flow into one of your bits of metal, through your bonding wires, and then out another bit of metal. In an increasing number of marinas, there are substantial DC electric currents running through the water.
Specifically, keep your metal keel/ballast, your metal rudder shaft, your engine/prop, and all thru-hulls electrically isolated, from each other, and from the engine. Bonding and Electrolytic Corrosion Due to Hot Marinas – Do not bond any thru-hulls or other immersed metal that can be electrically isolated.It is not necessary to include in the bonding system electrically isolated thru-hull fittings, if they are all of the same metal, or if they are protected by sacrificial anodes, as is common with propeller shafts. Items to be bonded include engines (use the engine negative terminal), the metallic enclosures of electrical appliances, motors, generators and pump frames, fuel tanks, fuel-deck fittings and lead-lined battery trays. It is laid inside the hull from stem to stern and those metallic objects that are connected are done so by using #9 AWG wire or larger. The heart of the bonding system is a “common bonding conductor”, which is generally a length of bronze or copper metal at least ½” wide and no less than 1/32” thick.Boats without permanently installed electrical systems do not need bonding. provide a low-resistance path for excessively high voltages, such as when the boat is struck by lightning.prevent the possibility of electrical potential on exposed metallic enclosures of electrical equipment.provide a low-resistance electrical path inside the hull between otherwise isolated metallic objects, especially those in common contact with sea water.The purpose of bonding, as described by ABYC, is to: ( Upgrading the Cruising Sailboat, p. Once you have electricity on board, even if it’s just an engine, battery, cabin lights and VHF radio, the possibility exists of electrolytic corrosion to metal parts of the boat.
0 kommentar(er)
