Generator Day


Last Updated on November 18, 2019 by Amy

We have a pretty massive generator – 12kW – onboard Starry Horizons. Because of our big generator, we got a big watermaker. We run our generator about every 4-5 days to fill our water tanks, but that’s not all we accomplish.

Since our generator is so big, the watermaker doesn’t apply enough load to be healthy for the generator. Usually, that means we run our air conditioning units too. But that’s not all we do!

Wash Clothes

A LOT. If it’s sunny out we can get four or five loads of laundry done in a day. Having the watermaker running too means that we can keep the water tanks topped up.

Dry Clothes

One of the issues we run into is the weather – in some places, it’s cold and rainy so we can’t line dry our laundry. Our washer/dryer combo enabled us to dry while running our generator, but just barely. If we had anything else using power, our inverter was unhappy.

The sun and wind make a good team drying our clothes.
Pile of clean laundry barely contained by our couch!

Replenish Our Hot Water Tank

The hot water heater only heats water when either the generator is running or the port engine is running. In the tropics, it’s no big deal because we usually take cold showers, but there are places where it’s chilly enough to need some heat. It’s kind of a vicious cycle actually; we take less showers because it’s cold water, but because we are taking less showers we use less water and therefore run the generator less often. Regardless, with the generator running for several hours to top off our water tank, we take full advantage by doing full showers, shaving, and any other personal hygiene that is better with hot water.

Charge Devices

The generator pumps power into our battery bank. We also plug in items that don’t need charging all that often, like our kindles or electric toothbrush.


  1. Hi, Just trying to understand the electrical system aboard the Helia. Why does the inverter become ‘unhappy’ during the high load of the washer/dryer while powered from the genset? I presumed that in this condition the inverter is not actually delivering power and all the load is taken by the genset. Also why is hot water not available with the starboard engine running? I thought that both engines had a 12V alternator on them. Sorry for the tech grilling, I’m considering a Helia and am trying to understand her quirks and limitations. Have read all of your posts from pre La Rochelle, keep them up. Regards

    1. Hi Gari, thanks for reaching out to us!

      I will do by best to answer your questions, but I first have a disclaimer. The electrical system on the boat is the system I am least comfortable with and my understanding of how things are set up have come from what I can remember from the electricians who have worked on the boat (and thus may be incorrect!). However, here are the (rather technical) answers to your questions:

      1) The inverter (or rather the charger side of the inverter) becomes unhappy because when we are running the generator, in addition to the washer/dryer, we are also running other 110v systems on the boat (such as our air conditioners or watermaker), and when the dryer cycle of our washer/dryer kicks on, it can exceed the capacity of our generator (depending on how many other systems are running). When that happens, the inverter/charger quickly swaps from charger mode to inverter mode to provide additional power to the systems that need it (the dryer). Once the dryer has started up, the demand on the genset drops, and the inverter/charger can transition back to charging mode. So perhaps “unhappy” wasn’t quite the right word, but instead it is doing exactly what it is supposed to be doing. We’ve only experienced this issue once, so we’ll experiment in the future with turning off an AC or two to see if that helps.

      2) This one I am actually quite sure about. 🙂 The boat gets hot water via two methods. The first is actually via the heat exchanger of the port engine which is piped directly to our hot water heater. The second is via electrical power when the genset or shore power is on and running. You are correct that both engines have 12v alternators on them, but these alternators are simply wired in to charge the batteries. We did consider having the hot water heater re-wired to be powered via the inverter but we had some concerns that the additional load from the hot water heater would max out the capacity of our inverter with all the other systems we use on the boat. If we ever upgrade the capacity of our inverter, we may make this swap.

      Hope that helps and please don’t hesitate to ask us more questions. We’ll answer them the best we can!

      1. David, thanks for that, another small step towards my understanding of the Helia’s systems. I had assumed that the inverter would be incapable of ‘joining in’ to provide additional ac power, I am aware from other interests how difficult it can be to synchronize ac power supplies. I will take you up on the offer to ask further questions as time progresses as I have an unending list! Thanks again

      2. Cool setup!
        Many of Mastervolt’s Combi Inverter/Chargers have that mode: it is called “power sharing mode” and if properly configured, as consumer A/C demand increases, if maximum allowed power is drawn from either the shore circuit or from the generator, these Combis will supplement A/C consumer power by drawing DC from batteries.
        This sort of “power sharing mode” setups are commonly installed on large yachts; the difference with a Combi is that the entire setup is contained inside the Combi box. Interestingly enough, the Mastervolt manual states some countries prohibit this mode. I am fairly sure any prohibitions are for regulatory, not for safety reasons.
        The only recommendation I have is to ensure the DC cables are fat enough to withstand the enormous demand the Inverter can impose on the batteries.
        BTW, David, what’s the max output on your generator, and what voltage and Hz does it output?

        1. Ah, interesting. When we were Stateside, we could only use our washer/dryer with the generator. Now that we are in Europe, use it rather freely at dock!

          1. I would assume this means you have European style power on the boat? (I hope so, otherwise I may need to rethink my whole electrical understanding!)

          2. Yes, the boat is 230v/50Hz. No 120/60Hz on board, at all. When we bought small items we could not source in the U.S. such as the Nespresso coffeemaker, or the Aeroccino, or a heat gun, we had to import the items from Europe. Which is a hassle. Other household items, such as the blowdryer, toaster, mixer, blender, etc., came with the boat. And some items such as the small, portable DeLonghi 1000W/2000W ceramic heater, we bought from Amazon US last year… $89.

    1. Hi Lorraine! I’m sorry I didn’t get to meet you in Tampa. I don’t think we knew you had a blog! We’ll take a look. We’ve heard your departure date is pushed back…hope to bump into you guys again out in the Carib. Thanks for following.

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