The Blue View - of Amps and Volts


Nine of Cups is happily parked in a marina near Adelaide at the moment. She is connected to shore power, and, for a change, I have no qualms about using a power saw or leaving my laptop plugged in. Having shore power is a luxury we don't often have, however, and when we are sailing or at anchor, energy consumption is always on our minds since we have to generate every watt we consume. So how much power do we consume and how do we make it?

Our biggest power hog is the freezer/refrigerator. When we were in Tasmania, NZ and Tierra del Fuego, trying to keep warm was a priority, and the refrigerator had no problems keeping things cold. Here in Adelaide during the summer, it's working hard to keep things frozen, and consuming a lot of amps. When it's cold outside, it requires about 36 amp hours to keep the beer cold and probably closer to 80 amp hours on a hot day. This translates to 432 watts and 960 watts a day, respectively. For comparison, a large household refrigerator/freezer combination draws around 4000 watts per day. One of the things I hope to accomplish while Marcie is in the States is to trim this hog down a bit.

Next in line in the power hog category are the laptops. We spend a lot of time each day writing, checking weather, communicating and watching the occasional movie. Then there's a bunch of small piglets... interior LED lighting, water pump, charging battery packs, anchor light, etc. And when we're sailing, we need power for the chartplotter, autopilot, radio, and navigation electronics.

So, tallying all this up, our power consumption ranges from about 130 amp hours, or 1.5kw at anchor on a cool day to about 2.4 kw sailing on a hot day. To put this in perspective, the average American household uses 11.5 kw per day.




To generate power, we rely primarily on our three solar panels and a wind generator. On a windy, sunny day, we can count on these to produce about 150 amp hours or 1.8 kw each day. So if it's a cool, windy, sunny day, and we're at anchor, we make more power than we need. If it's hot, calm, or cloudy, the solar and wind generator won't make enough power.

One option we have is a small, gas powered generator that I lug up on deck. It can pump about 30 amps back into the batteries, and can also provide power for the sewing machine or a power tool or two. The second option is to start the diesel engine and run it an hour or so. We try to avoid this option. Not only is it noisy, but running the engine with no load on a regular basis is hard on it, and causes a buildup of carbon.

Our goal is to consume only as much as we produce from the wind and sun… kind of like living within budget. We strive for “free” days when there is enough wind and solar to cover all of our power requirements … and then we catch a fish for sushi.


Days and Ways to Celebrate
A daily list of mostly obscure holidays and fun ways to celebrate them.
National Be Heard Day
This is a day to celebrate entrepreneurs and small businesses who employ nearly half the workers in the US (higher percentages in other countries), work long hours, have less dollars to spend, get less attention and still have to compete with large corporations. So support your local Mom & Pop shop. Spend locally.
Alexander Graham Bell Day
It's also the day that Bell was granted the patent for the telephone. Talk about being heard!