Setting Up Electrical Systems on a Boat

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Last Updated on September 8, 2019 by Amy

Electricity.  It’s something we use every day, but it’s always been one of those mysteries of the world to me.  Volts, watts, hertz/frequency and many other terms all seem like they’re from a foreign language.  Sure, I took physics in high school and can barely remember diagramming out various circuits and doing some calculations, but that was about the extent of my knowledge.  Until recently…

One of our biggest challenges on Starry Horizons is preparing the boat to be a world traveler.  On past travels, being prepared meant buying a few adaptors so you could still plug in your phone and laptop.  But things are never that simple on boats.  Not by a longshot.  Here, as briefly and clearly as I can put it, is the challenge we face.

Electricity throughout the world is generally set up using two different power systems, a 110v(volt)/60hz (hertz) system which is common in North America/parts of South America and what is used in the United States, and a 220v/50hz system which is fairly common throughout the rest of the world.

Fountaine Pajot offers to set up the boat using either system, and since we are based in the US and plan to return to the US once our travels are over, we elected for the 110v/60hz option.  The trouble comes in figuring out what do do when we are in countries that are shaded blue in the above map.

Our onboard generator will be sufficient to provide power for air conditioning and other AC (alternating current) systems whenever we are at anchor.  However, when we are staying in a marina, we don’t want to run the generator all the time and be “those people” who annoy everyone else around them, in addition to putting a ton of hours on the generator. Staying in a 110v/60hz marina won’t be a problem as we can just plug directly into shore power, however setting the boat up to be able to operate on shore power when we’re in a marina that has a 220v/50hz power system is the real challenge.

The Air Conditioning Dilemma

Almost everything on the boat can be run off DC (direct current, ie the batteries) power or has a small enough power draw that we can easily use an inverter.  

Except for the air conditioning units. We will likely be installing air conditioners from the factory, which are set up to run on 60hz and do not like running at 50hz.  (A fantastic discussion of what happens when you run a motor on a different frequency than intended can be found here)

In my research and in talking with our dealer, I understand that previous boats addressed this issue by buying “dual cycle” air con units that could operate on both 50hz and 60hz and then would use an isolation transformer to “step down” the voltage from 220v to 110v and thus would allow the air conditioners to work.  However, apparently the marine air conditioning manufacturers no longer offer these types of units.

So, as I understand it, these are our current options.

• Go without air conditioning in a 220v/50hz marina.
  • This can really depend on the scenario. Some marinas we’ve been to are breezy and comfortable without air conditioning. Others, like One15 Marina in Singapore, for example, are well protected and we received almost no wind.
• Run the generator at the dock in a 220v/50hz marina and be “those people”
  • While I’ve been told the installation of the exhaust of the generator is done in such a way to keep the generator very quiet, I still don’t really like the thought of continually running the generator 24/7 when in a marina.
• Install an isolation transformer that can “step down” to 110v and run the 60hz air conditioners on 50hz.
  • My understanding is this would cause the motor in the air con to run 20% slower, but would also increase the V/f ratio which would likely shorten the lifespan of the air con or could kill it outright. A few people have told me some manufacturers allow reducing the voltage to the air con when using 50hz in order to keep the ratio constant/similar, but I haven’t had a chance to confirm this with a manufacturer
• Combine a battery charger that can accept both cycles with a large inverter to power some/all of the air cons on board.
  • Our dealer has advised that the reaction time between the inverter and battery charger wouldn’t be quick enough as the battery charge would constantly be lagging behind the inverter.
• Install a “shore power converter” that would convert both voltage and cycles. I’ve also seen these referred to as frequency converters or voltage conditioners. They would convert 240v 50hz to 110v 60hz.
  • This is a very expensive option, and getting one large enough for our needs would be quite heavy and take up a lot of room on the boat.

Installation of Shore Power Converter

This was the biggest and most complicated project by far that we tackled when we arrived in Florida. I haven’t heard of another sailboat in our size range that has this equipment on board, so there is a very good chance that Starry Horizons may be among a small handful in the world, and likely is the only Helia in the world, that has this equipment installed.

The complicated explanation (stop reading now all you technophobes!) is that the shore power converter will take the shore power input (AC power), convert it to DC power and then re-convert it back into AC power at the 240v, 60hz power that is used onboard Starry Horizons. So even though the input power may be at 230v and 50hz, the power we’ll be able to use onboard will be nice clean American style power.

We decided to install the unit because we will eventually be staying in marinas around the world where the input shore power will be different than the power that is used aboard Starry Horizons and being able to easily operate all equipment onboard (air conditioners especially!) will be very nice. Plus, we didn’t want to be those people who have to run their generator at the dock to keep their batteries topped up!

A few more technical details… the entire converter is made up of 3 components: 1) The control unit 2) the transformer and 3) the inverter. The transformer is extremely heavy (it was quite entertaining watching the 4 guys moving it onto and around the boat!) and the only place we could find room for everything was under the master berth. There is a fiberglass lining that FP made for storage under the bed that had to be cut out so that the control unit and inverter could be mounted to bulkheads. A special platform was glassed into the floor of the compartment so the transformer could be bolted down and special supports were made to help prevent it from coming loose while the boat is underway.

Needless to say, this was an extremely complicated install and probably the main reason for our extended stay in Miami.

So Plugging in is Easy, Right?

No, no it’s not. While we’ve been cruising many places that are 220-240V/50 Hz, it’s not as simple as plug-and-play.

First, just because these countries are on the same voltage and frequency does not mean that that are using the same plugs. We now carry two shore power plugs with us; one American-style plug and one Australian-style plug. Sometimes we’ve had to buy new plugs and cannibalize them to make a franken-plug that works for us. Other times, we’ve rented an adapter.

The 240v 50hz to 110v 60hz converter is HEAVY. We easily added 500 lbs to the stern of our boat.

And, it lets off a lot of heat. If we are plugged into shore power, we have to be running an airconditioning unit, otherwise, the 240v 50hz to 110v 60hz converter will overheat.

Would We Recommend a Shore Power Converter?

No. In fact, we’d like to get rid of ours. Does anyone want one?