Sunday, April 6, 2008

Electrical Systems And Your Boat

Corrosion can take its toll even on the interior of your boat due to leaks, salt air and humidity.
Your Bottom Paint - Your bottom paint has a lot to do with electrical systems? Its because of copper based paints. The next time your boat is hauled and you see large burn patterns around all your underwater metals, you got a stray current problem. Copper-based bottom paints react severely to stray current, and serves as a great indicator. Of course, the common thing people say is that the stray current "is from the marina." Or it's the other guy's boat that is causing the problem. Don't bet on it. Most stray current problems are sourced on the boat in which they appear. Otherwise, everybody in the marina would have the same problem.

Electrolysis and Galvanism
Electrolysis is a word that is miss used by boaters who don't really know what it means, so let me correct this right now. First, understand that all boats have an electrical potential. That's because of all the different metals on the boat which, themselves have differing electrical potentials. This is exactly the same principle that makes a dry cell battery generate electricity. This electrical potential is called galvanism and is the reason why we put zincs on boats.

Electrolysis is stray current escaping from the system and is most damaging. It is an abnormal condition. When this happens, it will eat up the zincs in no time, usually leaving that metal looking bright and shiny. Therefore: Shiny zincs = electrolysis. Dull eroded zincs = galvanism. Zincs will erode rapidly and underwater metals begin to be affected.

Shore Power Cords
The single largest cause of problems with shore power systems results from failure to maintain the connectors on both the cord and the boat connectors. These devices are exposed to water and over time suffer from corrosion and general wear. High resistance caused by corroded, bent or worn connectors results in high resistance which causes overheating, which further amplifies the power drop. This not only creates conditions for a potential fire, but causes electrical equipment to work harder, resulting in reduced life span of equipment.

POWER CONNECTIONS - You can perform a very simple check just by placing your hand on the shore cord near the connection to determine if it is heating up. Obviously, this should be done while you have a lot of equipment turned on. If it's anything but slightly warm, not more than 110 degrees, suspect a problem. Shore power connectors should be dismantled at least once per year, cleaned and repaired as necessary. Most of these connectors have replaceable parts. If you drop your shorepower connector in the water, you must take it apart, clean and dry it. Otherwise, expect it to burn up.

Buy quality power cords, as these will last longer and have the advantage of replaceable connector parts. Cheap connectors usually can't be taken apart. Also don't use the three-pronger household type adapters as this type of connector is highly unreliable and prone to causing system faults and fires. Only the twist-lock type connector is suitable.

One more thing: If you are not turning off the dock breaker before disconnecting the power cord, start doing it now. Not only do you risk getting electrocuted, but disconnecting an energized connector damages the contacts. Also consider what happens if you drop the energized cord in the water.

Circuit Breakers
Circuit breakers wear out, and when they do they work less well, or not at all. If you are using circuit breakers as ON/OFF switches, you are helping them wear out that much faster. It also damages breakers when you shut off equipment via the breaker. This causes arcing at the contact points which damages the points. When connecting and disconnecting shore power, you should always turn OFF equipment at the appropriate switch on the equipment. Then shut the main breaker off. Do not ever simply throw the main breaker off to shut down equipment that is operating. The circuit breaker arcs and damages it.

Also be aware that any equipment run by a motor, such as air conditioning and refrigeration equipment, start up with an initially much higher amperage than the normal running amperage. An air conditioner that runs at 14 amps may have a start up amperage of 20 amps, so that if you just go and turn all the equipment on at once, it overloads the system. Then the circuit breaker gets hot and won't stay engaged until it cools down. Start up heavy equipment one item at a time, allowing it time to cycle into its normal operating voltage before turning something else on. For example, don't turn the AC, refrigerator and icemaker all on at once and not expect the breaker to pop.

Chronic Breaker Popping
It's human nature that when a problem appears, we wish it to go away. Breakers that pop frequently are signaling that there is a problem, which could either be the breaker, or something in the circuit. Yet most people will keep on attempting to make the breaker engage. This can be dangerous because you may cause the contact points of the breaker to fuse together from arcing, in which case it will never trip again. DO NOT ATTEMPT TO ENGAGE A BREAKER THAT IS OVERHEATED BY FORCING IT. You must allow it to cool down.