Check your shore power

One of the pleasures of being a sailor is that occasional shore-side visit in some foreign exotic port. When I was a young sea pup serving aboard the 312-foot destroyer escort USS McMorris DE-1036, I was one of the biggest liberty hounds on board, but was always one of the last sailors to depart due to shore power. I was one of the ship electrician mates and as such it was part of my job to hook up shore power and shift the ship off of ship service generator power and onto shore power. Besides the actual physical hookup, it was important to check shore voltage, frequency and phase rotation before trusting it to run shipboard electrical and electronic systems. As a boat/yacht owner it is just as important for you to ensure the quality of your boat’s shore power as it was for Navy ships to do so.

Voltages come in a wide variety of combinations throughout the world due to varying shore power standards, but most inductive devices such as transformers and motors require a specific voltage to keep from overheating and for optimum operation. This is why you need proper and fairly sturdy line voltage without fluctuations, because when line voltage goes lower than optimum, appliance motors will draw higher currents, overheating them and your boat’s wiring.

Shore power frequency is also important. It comes in two varieties: 50 Hz or 60 Hz. If you run inductive equipment (motors) designed to run on the higher 60-Hz frequency on the lower 50-Hz, the motors may run slower or use higher current. Also, a 60-Hz transformer being run on 50 Hz will also draw more current and run hotter. Of course, resistive devices such as heaters will work just fine on 50 or 60-Hz frequencies. There are all kinds of electrical devices designed to protect and enhance shore power, everything from isolation transformers to inverters to power supplies, but the ultimate technological solution is known as a static frequency converter or solid state frequency converter.

These converters are designed to accept a wide variety of shore power voltage and frequency and to output clean power at your boat’s designed voltage and frequency requirements. The converters input is the AC from the shore power source, which is then rectified to direct current (DC) power internally. Then a built-in high efficiency inverter takes the DC power and creates your desired AC output voltage and frequency. Originally, these converters were too bulky, heavy, and expensive for smaller boats, however that has changed due to improvements in technology.

Today, companies such as ASEA manufacture static converters as small as 8 kVA, single phase which is bulkhead mounted and weighs only 230 pounds. ASEA has a great variety of other more capable units that go all the way up to 500 kVA and three-phase models. Here is ASEA’s website:

The following is a list of other manufacturers who build boat electrical equipment specific to shore power/power generation. This list is from the Marine Electronics Buyers’ Guide put out by the National Marine Electronics Association (NMEA).

Analytic Systems

Atlas Marine Systems

Charles Industries

LaMarche Mfg.



Professional Mariner, LLC

SAM Electronics

Victron Energy B.V.

Xantrex Technology Inc.

Fredrick Gary Hareland holds an AAS degree in rescue and survival operations and in avionic systems technology and is a certified marine electronics technician and NARTE certified telecommunications technician. He has served in the U.S. Navy, Coast Guard, the Military Sealift Command-Pacific and has worked for Maersk Line Limited and Norwegian Cruise Line. Hareland currently works at China Lake Naval Air Warfare Station as a microwave-communications technician. He lives in Ridgecrest, Calif.

More articles by Fredrick Gary Hareland:
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By Ocean Navigator