Power is Critical on Boats, How Did we Install an Inverter….45

In 2016 & 2017 we were hunting for a new boat, we had sold our Grand Banks and were looking for the perfect boat for our adventures.  We purchased a 1980 Hatteras named Sheer Luck, which we knew needed quite a bit of Remodeling & Upgrading  before our adventures began. We spent the next 16 months working on all of our listed improvements which included adding an inverter system. I asked Dan to help write a more detailed overview of the decisions and steps included in the complicated process.

WarningPLEASE DO NOT attempt this effort yourself, unless you are a strongly skilled Electrical Engineer. Dan has the skills & took multiple precautions to not hurt himself. It can be deadly if you are not aware of what you are doing.

~~~~~~~ Here is Dan’s Story ~~~~~~~

When we bought our Hatteras, it had lived most of its life as an East Coast charter yacht. It was set up to run with 3 crew and 6 guests.  That is a heavy hotel load. She was being operated in the Florida and Bahamas area which included heavy use of the air conditioners. With that many persons on board, the water maker, galley, and hot water heater were in frequent use. Thus, when we bought the boat, it was equipped with 2 Northern Lights 32KW Generator sets for power. It had no inverter.

Why is an inverter important to us? An inverter converts battery power to AC line voltage silently.  IMG_1871When at anchor, which for us is frequently, we like the generator off as much as possible, but still want our conveniences to keep going. Key loads the inverter runs all the time are refrigerators and freezer, the freshwater system, toilets, and lighting, as well as battery chargers for the 12V systems around the boat. The inverter can only run for 8-12 hours before we must start the generator and recharge the house battery.

So getting to where we wanted to be, with a nice inverter system, was not easy. The boat was built in 1980 and not designed to include an inverter. You had shore power or the generators, period.  Also, this boat uses a lot of power. It has two main 50 Amp 240/120 Volt, split phase shore power cables, 12KW, and one more auxiliary cable for good measure. The generators can deliver 80 Amps of 240V/120V, at 20 KW. We had to decide how much inverter, and how large a battery, what would it power, and how would we integrate it. At this point I must mention that I am a USNA Graduate with a BSEE in Electrical Engineering, and a Rickover trained Navy Nuclear Submarine officer. I was the Electrical Officer for 2 years. I know a few things.

I did a lot of research. I had inverters in 2 prior boats. One of which, I had installed new. But it was tiny, and only made 120V. I tried to see if a simple small system could be used on this boat. It turned out some of the key loads were 240V loads, so that eliminated many choices.

About this same time my friend Ron Micjan was facing a similar problem on his big Zephyr, (an 86′ research vessel).


Only he needed a 3-phase inverter.  I learned a lot during his installation, with my many conversations with him, along the way. It was to power all the panels but control the loads so as not to overload the inverters. Yes plural. He settled on using 3 Victron 5KW Quattro inverters, wired for 3 phase AC. It was at this point I learned I could wire 2 of them for 240/120V split phase AC, one for each phase.

These inverters have 2 AC inputs (shore power and generator) and 2 AC outputs (pass through or inverting from the battery). So, I could pick one of the shore cables as an input and one of the generators as an input.  I decided to make the output go through one of the shore power supply breakers. This would limit the current to 50A max and made the boat act like it was on one shore cable when we were on the inverter, which is a common practice. I also thought I would need solar or wind as an additional power source for the house battery, so I added a very flexible solar charge controller into the design.

I talked all of this over with Ron, and even stole his bus bar design for the Victron Telecom batteries. I designed the installation to go in the “doghouse” area behind the main deck helm, as it was low, dry, and not in the engine room or under a bed. Inverters have fans that make noise and batteries can smell sometimes.  With his help, I ordered up over $10,000 worth of stuff, which included a pair of 5KW inverters, solar controller, lots of heavy wire, batteries, special fuses, connectors and battery boxes.

Inverter diagram from Dan

In the cold winter in Portland, in a big boat house, the electrical surgery commenced. First was mounting the inverter boxes – had to do some woodwork for good mounting.  Then install the batteries in their boxes in a cramped doghouse. Wow!  img_1550_originalThat was tight heavy work, but Angela pitched in and we got them in and arranged and clamped down. Then I could make measurements for cutting and drilling the giant heavy custom copper bus bars to connect the 8 batteries into an evenly wired bank of 4 pairs for storing 800 Amp-Hours of energy at 24 Volts.  Now measure, make, and install all the battery cables and ground cables.  DC side is done. Inverters power up fine, then are secured.

It was time for the AC side. A careful review of the Hatteras drawings and physically inspecting the switchboards front, back, inside and out was first. I had to ID what wires to cut, where to connect new wires etc. I also had to make some new labels.  A lot of pulling, snaking, measuring, cutting, crimping and insulating occurred. Double checked every wire to the drawings and the inverter manuals.

Then it was time for some tech support. I had to program the inverters to know they were a split phase pair. The Victron rep sold me some computer to Victron adapters and taught me how to use them. Plugged that setup into USB on my laptop and boom, they were setup. That actually took quite a while to complete this.

img_6977I started it up and it worked great. Adjusted a few things and learned what to turn off and what not to do while running on inverters.  We do not run the water heater, dishwasher, 32V battery charger or the crane on the inverters. No big loads. We can run one burner on the stove, and it runs all those important background items mentioned earlier. And we have lights at night without running the generator. It can run a quiet boat for about a day if the shore power goes out. At anchor, the system usually discharges the battery to 65-70% level by morning when we get up and we start the generator to recharge it and run other heavy loads.

What about solar? The sun shines when we don’t need the extra power.  Never built a wind generator, but that is still an option. Extra Amps come best at 12-5 and 10pm to 7am. But I had that fancy controller which was looking for 32-48V DC.  Ah Ha! On my main engines I have huge 1600-Watt alternators that put out up to 37 Volts.  I had one extra 30 Amp circuit breaker on my main 32V(nominal) panel. I decided to wire from that breaker to the solar controller.  When the engines are running when we are cruising, I set up the system to pull 28 Amps off the alternator to charge the house bank and run the inverters. This turned out brilliantly.  We have over 800 Watts of power we can convert into running the light hotel loads while cruising and keep the house battery charged.  We no longer run the genset while underway. Only for charging, making water, heavy cooking or extra heavy loads etc…

So that project was KEY to enabling how we like to cruise, and to keeping the lights on and freezers cold all the time.

What is the moral of the story? The next boat we buy will already have the inverters installed!!

~~~~~~ Hope you enjoyed Dan’s Inverter story~~~~

We did do some cruising without an inverter, up into the San Juan Islands in 2017. It was a bit comical having guests aboard while anchored out & no inverter. When the generator was turned off for the night, we would make sure everyone was in their stateroom with flashlights because when it when off, so did all the non-essential power for the guests. No lights, charging your phone or even flushing the toilet, as the water pump was not working either. Needless to say, it was kind of a “good night John boy” event when the lights went out. We were certainly not feeling comfortable in this situation as hosts with our guests.

Dan and I are both much happier with the inverter running our boat 70% of the time while at anchor. It makes the days and nights perfect, quiet and enjoyable. And you  know the saying… Happy Wife, Happy Life!

I hope you are all staying safe!

Please let us know if you have questions or an ideas for a blog. I might be able to pin Dan down for another technical overview if a request is given!

Take Care! 




7 thoughts on “Power is Critical on Boats, How Did we Install an Inverter….45”

  1. Once again a great article. I could almost do it myself,yeah right. Thanks again for an enjoyable read 😀.

    1. Thanks Mike! You ever need help you know how to get a hold of Dan!!

  2. Give my thanks to Dan for his story of the power upgrade. As a ChemE, I understood some of that… I think I’ve told Dan before that I think of power distribution as electrons running like a fluid through a pipe, haha.

  3. That was a big project with a great outcome. We have seen several sail boats around Annapolis that have wind-powered generators. The propellers are about 18″ in diameter. I do not know what their output is, but it might also be a supplemental option to consider.

  4. Uninterruptible power supplys are available (free or very cheap) at the local dump or at the scrap yard. Most folks toss them when the batteries give out. My first one will handle 1500 watts at 120v . Just remove the old internal batteries and connect to your house 12 volt battery. When you disconnect your shore power the UPS WILL kick on automatically. No worries about turning on or off the inverter! Hope this inspired someone!

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