Electric Conversions: Easy, Safe, & Worth the Added Value

In August 2002, one of our clients finished converting a 70’ Princess™ purchased in Spain from European to American specifications. Several marine electrical contractors bid this project. The bids were from a few thousand dollars to close to thirty thousand dollars. The accepted bid came in at $10,500 but increased to almost $15,000 after the owner opted for several improvements. Let’s talk about what was done and why, and let’s discuss the issues that we had to resolve.

230 Volts AC vs. 110 Volts AC-Dockside to Vessel

This is really a non-issue, but it must be covered for those who think it is an issue. First, most US marinas have 230 Volts AC on the docks and all large US built yachts use 230 VAC because it’s more efficient than 115VAC. It’s more efficient because the same size wire will carry twice as much 230 VAC power (measured in amperage) as 115VAC. Yachts are more efficient when they have less wiring to carry; that’s the reason bigger yachts use higher voltage (Imagine if all yachts carried only 12VDC power; the wire gauge used to carry this power would have to be as thick as the battery cables on your car. Multiply that weight times the thousands of miles of wiring on large ships and you can understand why higher voltage is necessary with big yachts). Also, long electrical runs tend to heat up wiring which is why larger yachts also prefer higher voltage. The higher the voltage, the more efficient it is, and the least likely it is to heat up a wire that will cause a fire. Let’s be honest-- it’s a plus that European yachts don’t have an 115V shore power cord for the larger models—they’re useless because even at 50amps, 115VAC doesn’t carry power to run all the AC’s on a 68’ Princess. However, for those of you who frequent small marinas that don’t offer 230 VAC, you’ll have to carry a “pig-tail” aboard to produce your own 230VAC. A pigtail is an electrical cord that looks like a “Y” with two 115VAC male plugs on one end (dockside) and a female 230VAC outlet on the other side. The two male 115VAC plugs are inserted in the dockside sockets, and the yacht’s shore power cable is inserted in the pigtail’s female 230VAC socket. .

230 Volts AC vs. 110 Volts AC-Outlets Aboard

It’s not practical to have European 230VAC outlets on an American vessel in American waters. Of course, we could pretend that we’re traveling in Europe and take our small converters that we could plug in the Euro outlet and get 115VAC out to power the odds and ends that we bring aboard such as razors, electric toothbrushes, vacuum cleaners, and a toaster. But, although this option is a lot cheaper, it’s not convenient. And if we’re going to save hundreds of thousands of dollars by importing a vessel from Europe directly, why should we save pennies and sacrifice convenience.

Wiring and Outlets

Fortunately, Princess™ Yachts have wiring that is acceptable both in the USA and Europe (This is not the case with all European yachts). Princess™ must have decided that it’s cheaper for them to wire their vessels in this manner rather than separate their production line. Princess™ could have wired their European vessels with a smaller gauge 230VAC wire suitable for Europe, but instead they selected to use a gauge also suitable for the USA. The electrical sockets aboard, however, have to be changed to accept the American three prong power cord. The other option is to buy an American insert (the kind you take along when traveling to Europe) that can be purchased from West Marine or your favorite luggage store. If you prefer to change the entire socket: they are 3 wire, 16 Amp, 115v ”Hamilton Sistema 45 ave” made in Italy and can be purchased from marine electrical suppliers. Also, these can be ordered directly from Princess™ UK on line with a credit card.

. . Producing 115VAC on board

There are two ways this can be accomplished. The first is to use a step-down transformer (they’re cheap). This transformer would have to be connected between shore power and the electrical panel as well as between the generator(s) and the electrical panel. However, the better way to do this is to connect an inverter between the house batteries and the electrical panel to feed all the outlets. This is more expensive, but the advantage is that the outlets can be used underway even when the generator is not being used (the two alternators on the engines are plenty powerful to reload the house batteries even if the drain is high. And, the house batteries’ total amperage is enough to run all the entertainment equipment, a toaster, a vacuum cleaner, and an electric shaver all at the same time). The second advantage: since you need an inverter to run the entertainment equipment when you’re on the hook without the generator running, why not buy a bigger inverter, run less wiring, and keep it simple. In other words, there’s no need for a heavy step-down transformer AND an inverter.

50 Hertz versus 60 Hertz

In Europe the electricity is pulsed through the wires at 50 times per second whereas in the USA it’s pulsed at 60 times per second. Does this matter? Will your coffee taste different in the USA if it’s brewed using 50Hz? Or will your toast be crisper at 60Hz rather that 50Hz? The answer is “No.” But there are some things that will run differently at 50Hz rather than 60Hz. For example, a digital clock built for a 50Hz environment will gain 12 minutes every hour (a bonus only for procrastinators). So, the correct answer is “yes” and “no” depending upon the type of electrical equipment you are using. (For a more complete treatment of this subject go to International Power and Standards Conversion.)

What’s important for us is to know what will work on the boat and what won’t work. Everything that goes through a power supply before the power is used will work the same at both 50 and 60 Hz. For example: amplifiers, computers, radios, razors, electric toothbrushes, etc. Also, everything that produces heat from electricity will also work at both 50 and 60 Hz. For example: stoves, dryers, toasters, etc. But, if an electrical appliance uses the AC power to directly turn a motor (without going through a power supply that converts the power to DC power), then the speed of that motor will be affected. For example, if the fan in the air conditioner’s air handler is rated at 50Hz, if it’s run on 60Hz, the fan will turn 20% faster. Or, if a 50Hz pump is run in a 60Hz environment, it will push 20% more water.

Once again, we must thank Princess™ for their forward-looking thinking. The AC raw water pumps on all Princess™ vessels run at the same speed in both 50 and 60 Hz environments. Also, all the Cruise-Air air handlers are also rated for both 50 and 60 Hz. But the big bonus is that all the refrigeration equipment (freezers and refrigerators) can be run at either 24VDC or 230VAC. The selection can be made on the electric panel. So, if you believe that your 50Hz appliances will run differently on 60Hz (not likely), set the switch for 24VDC on the electric panel (There’s a small advantage to that strategy: batteries last much longer if they don’t discharge. When the yacht is idle, letting the refrigeration equipment run on 24VDC will help the longevity of your batteries because the batteries will be continuously charged). Besides, with DC voltage, there are no hertz so it can’t possibly hurt the equipment. In other words, hertz can’t hurt if they first go through the battery charger. And finally, all the battery chargers aboard Princess™ yachts are made in California and accept any current from 90VAC to 250VAC at 50 or 60 Hz.

What are left are the dishwasher, washing machine, and the microwave oven. In theory, these appliances should work but at different speeds. And, that has not always been our experience. You’ll have to go through the wash cycles 20% faster than in Europe. So, the answer is simple: pick a longer wash cycle. But, with the microwave oven, you might have to buy an American 50Hz oven--It seems that some magnetrons don’t like cycles to vary. Princess™ uses Panasonic microwaves but we have seen different brands. It’s always better to call the manufacturer to check what they say. If they say no, what’s a $200 Microwave in the scheme of things.

Finally, a word must be said about Hertz Converters. These are huge and expensive pieces of equipment that convert AC current from 50 Hz to 60Hz or vice versa. Should they be used? The answer is no if you plan to use your yacht exclusively in the US. However, if you plan to move your yacht to the Mediterranean every summer then the answer is “Yes.” Large charter yachts that move from the Med to the Caribbean every year all have hertz converters. Larger yachts over 100 feet should buy converters because the conversion process is easier and on a future resale, the entire world is their oyster. Whereas smaller yachts that plan to stay in the US need to get used to the 60Hz environment. It’s a little bit like being raised in Germany and emigrating to the US—you had better learn to speak English—it’s easier. Because, on the long term, where in the US are you going to buy a 50Hz washing machine when it needs to be replaced?

Isolation Transformers

The largest expense on the $10,500 electrical conversion was the two 50Kva isolation transformers with galvanic isolators that were purchased to completely isolate the vessel’s electrical system from shore power. Were these necessary? In practice, we could have hooked two US power cords to the boat by using the two 115VAC legs from shore and the neutral and disregarding the return. In fact, we did this, and it worked. Many years ago, in the US, this is the way we brought 230VAC into a house or boat. Today in the US however, we use a 4-wire system with two 115VAC legs, a neutral, and a return. In Europe, they use a 3-wire system: one 230VAC leg, a neutral, and a return. The risk of using the neutral to return the current instead of the 4th return wire is that in case of a short on the boat side, it could cause a fire. This is a remote possibility, but it can happen, so the question is to determine if $6,000 in isolation transformers is a good fire insurance premium to pay. In our opinion, and in the opinion of the American Yacht Builders Association, it is. Besides, there are some added bonuses. With galvanic isolation included, the odds of electrical leakage in the water (that creates electrolysis) lessen tremendously. A second bonus is that these transformers completely isolate the vessel from the vulgarities of electrical power production in all the marinas you may visit. Marinas in Florida and the Bahamas are well known for their brownouts that can destroy sensitive equipment such as the compressors on refrigeration equipment. Or, if electrical spikes are produced on shore from such sources as a jackhammer or a lightning strike, these too will be stopped before they can damage equipment aboard. In conclusion, isolation transformers are needed to safely convert European 3 wire 220VAC vessels to an American 4-wire 230VAC environment. The final conversion result is that the Euro converted 3 wire system with isolation transformers will be better for your yacht than an American 4 wire system without an isolation transformer.

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