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Old 17-04-2008, 15:13   #1
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dc or ac electrical system

Greeting All. I am looking for online articles comparing dc marine electrical set-up versus ac marine electrical set on cruising boats. I have stumbled across such in the past but cannot now locate these articles. Your help is appreciated.

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Old 18-04-2008, 03:10   #2
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What do you want to know??? We have some of the best in the world of electrics as members here.


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Old 18-04-2008, 03:48   #3
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re: DC or AC

I have seen articles outlining the best approach to electrical power for living aboard ship. Battery banks, generators, ac alternators, inverters , solar, wind ect. Cooking, heating and cooling and basic power needs. Reliability, cost and comfort are the issues with me. What is the best basic approach to providing electrical power aboard?
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Old 18-04-2008, 05:19   #4
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Basically, you want a robust 12V system with multiple charging sources which are well regulated and can be turned on and off. Most marine gear is DC, 12v or 24v.

Then do a AC system to run from shore power when you are dockside and an inverter to convert your DC to AC for the AC equipment you decide to use. The conversion consumes power and the more amps you use the larger the inverter need be and the associated wiring. Running AC aircon will take some huge batts for example and a large inverter.
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Old 18-04-2008, 05:29   #5

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And... it depends a great deal on your intended use. Are you a trawler, or someone who motors constantly? Are you a sailboat who won't have a lot of power?

Different types of boats (who use their engines differently) have different types of power system to take advantage of the most readily available power source.

DefJef's sytem above is most common on cruising sailboats. On cruising trawlers you might find an almost all AC power system, with electric stove and oven and generator that runs at anchor.

More details will help us respond.
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Old 18-04-2008, 07:44   #6
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AC or DC

I am oriented toward small motorsailers. The fact that I would need paravanes and all the attendant rigging for comfortable cruising was the deciding factor in choosing a motorsailer over a small trawler. Being working class decided me on a small boat. Motorsailing, motor slowly ticking over, sail full to pull. Sails to get back to dry land if needed. Motoring if I must or feel the need for speed. (7 or 8 kts.)
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Old 18-04-2008, 07:59   #7
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There's still a lot of missing info to complete your request. You have to set out a program for your vessel and include things like:
  1. Size, LxWxD, weight etc?
  2. How many crew?
  3. Endurance expected between shorepower outlets?
  4. Maximam capacy for storage batteries?
  5. Electrical loads, lights, heat, cooking, windlass, winches etc. (electrical budget) Calculating Your Electrical Load - SailNet Community
  6. Charging capacities, engine, solar, wind, other, etc.
The list of questions will go on and on unless you can nail down a few of the basic facts. A motorsailer can be a lot of things to one person and have all the latest gadgets or it could be a fully utilitarian vessel with oil lamps. A basic understanding of boat electrical systems and terminology is in need here. This is just one of many that might help you get started.

Marine Electrical Check List

When you feel you've got a better idea of what your needs are then we can (and are usually more than willing) help. The guys here helped me design my boats electrical system.
Yours Aye! Rick
"It's not the boat "you built" until you've sworn at it, bled on it, sweated over it, cried beside it and then threatened to haul the POS outside and burn it!"
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Old 18-04-2008, 08:35   #8
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Inventorying your power needs is a necessary first step. Only then should you begin to decide what to install to meet those needs.

If you're going to have significant AC loads, like air conditioning and domestic water heating, you might want to go with an AC generator to power them directly, without losses through an inverter. The AC genset would charge your battery bank and run DC loads through an inverter (true sine wave type preferred).

If most of your loads are DC, you have choices: diesel powered DC genset, a high-output alternator on your boat's engine, solar panels, and wind generator(s). These can be installed in combinations, with appropriate charge controllers to safely charge your battery bank. A DC genset can run fairly large AC loads through inverters up to maybe 3,000 Watts, but you lose some energy in the conversion process.

There are books and websites available to help you sort through all this. Google around a bit.

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