The Electrical Energy System by Kevin Jeffrey

Having a reliable source of electrical power on board is crucial to being able to enjoy your time cruising. The further afield you travel, the more you'll find this to be true. Ask anyone who has finally made it to the islands, only to have his stay in paradise ruled by the constant need to run the engine for battery charging. The threat of dead batteries looms large on every cruiser's mind, yet maintaining an adequate supply of power can be easy, especially for those cruising on multihulls.

In many ways, the ease of finding an energy solution relates to how you approach the problem. For a start, most cruisers don't take their energy situation seriously enough until it's too late. They are used to having power whenever they need it at home, dockside, or in an automobile, so they make do with inadequate energy equipment while they upgrade all the other systems onboard. What they tend to forget is that many of those other systems are dependent on a reliable supply of electrical power.

On a boat, as soon as you leave the dock you are essentially managing your own little electric utility company on board. You have to accept the responsibility this position entails or suffer the potential consequences. Your job as utility manager is to select power-generating equipment and adequate storage capacity, then establish a comfortable charging routine that avoids brownouts and blackouts. You also want to choose efficient appliances that reduce your load without sacrificing performance. They may cost a bit more initially, but efficient appliances mean less generating power needed to run them, and that can yield big savings for a modest investment. Now you're starting to think like a utility manager!

You should also have proper monitoring equipment so you'll know exactly how your system is performing at all times. Energy meters and monitors make electricity visible, thus helping to eliminate the mystery. The rest is simple. Balance the energy produced with the energy consumed and you're well on your way to energy independence. It takes a little effort and a reasonable budget for initial set-up, but managing your own energy supply can be intensely satisfying.

How do you go about setting up a proper energy system? Many cruisers can piece together a reasonable system on their own using resources such as the Boatowner's Energy Planner. To avoid unnecessary effort and expense, however, most cruisers use books as a primer for working with a qualified energy professional who can accurately assess their needs, is capable of supplying a complete energy package and, most importantly, is willing to stand behind his product if a problem develops in some far-off cruising ground.

The Hamilton Ferris Company is a good example of a complete marine energy supplier. They make it easy for multihull cruisers to set up an energy system by offering their Ferris Power Survey. This is a modestly-priced, professional design service that allows the company to tailor an energy system to a cruiser's individual situation, including his type of boat, how and where he intends to cruise, his personal preferences regarding energy gear, his current and future electrical load, and the charging routine he feels most comfortable with. Ordered by phone, fax or mail, the survey outlines an energy system that is custom-fit to a cruiser's need, anywhere in the world.

I like this type of service since it helps a cruiser sort out his energy needs and quickly outlines a plan of action that works. There are several other complete marine energy system suppliers, including Jack Rabbit Marine and Everfair Enterprises, from which to choose.

Before embarking on an energy system design, it's advisable to become familiar with the various types of marine energy equipment currently available. A good place to start is with the equipment that generates power, including gear that uses renewable sources of energy, such as solar panels and wind or water-powered generators, as well as gear that relies on fossil fuels, such as high-output alternators, portable generators, and gen-sets.

Unlike any other piece of marine equipment you buy, renewable energy gear actually pays for itself over time. Cruising multihulls, with their wide decks and transoms and their superior speed, are perfectly suited to gear using renewable sources of energy. The extra weight of the gear is more than offset by the reduction in engine fuel for charging batteries.

. Most cruising multihulls have abundant space for locating a sizeable array of PV (photovoltaic) solar panels that transform sunlight directly into electricity. Don't let anyone delay your purchase of solar panels by saying how they're the thing of the future. Like multihulls themselves, this technology is perfected and ready for tough cruising conditions right now. In fact, today's solar cells are more efficient at converting light to electricity (12-14%) than incandescent bulbs are at converting electricity to light (10%). Over the years, forward-thinking multihull enthusiasts have helped bring PV solar use into the mainstream. If your load is light, solar panels can easily provide up to 100% of your energy demand, as it did on both of our own cruising catarnarans. For larger loads, solar can be an effective contributor in a diverse energy package.

Wind-Powered Generators. Cats and tris also offer a wider selection of mounting locations for wind-powered generators. Wind units come in two basic types. High power, large prop units made in the U.S. use 60-72 inch diameter wind blades to produce up to 15-20 amps of current in 20-25 knots of wind. They can be mounted on a pole at the stem, hung in the fore-triangle for use in port, or mounted on the front of a mizzen mast. Look for units that can be made self-limiting in high winds (over 25 knots) and can be converted to a water generator for longer passages. Small prop, multi-bladed units made in Europe produce much less power, but are typically self-limiting by design and pose less of a hazard when mounted on a boat. With their 36-40 inch diameter blades, they work best in windy locations or as part of a diverse energy package.

Water-Powered Generators. These are by far the most underrated and least understood source of marine electrical power. They use the motion of a sailboat, or the power of the wind on the sails, to produce electrical power. Most units currently available are trailing-log types. A small prop mounted on a stainless steel shaft is trailed through the water on 60-100 feet of tightly wound line. As the line spins, it turns an electrical generator mounted on the stem of the boat. Water-powered generators can also be Strut-Mounted units that trail in the water just behind the boat from a submerged strut, Outboard-Leg type units that mount on the transom like an outboard motor, or Prop-Shaft units that utilize the power of a rotating prop shaft while the boat is under sail. The drag of a water-powered generator is negligible on a multihull. Don't let the small size of these machines fool you; the high average cruising speeds of a multihull produce a truly phenomenal amount of power, with daily averages approaching two hundred amp-hours!

High-Output Alternators. For those with an inboard engine, a high-output alternator gives you the most power for the smallest financial investment. These units are not just standard alternators with a higher output. They are quite different in how they are constructed and controlled. They run cooler, produce more power at lower rpm (revolution's per minute), and charge batteries more quickly and more fully. These units are moderately priced and the small and large-case models are made to be direct replacements for the standard alternators found on most engines.

Portable Generators and Gensets. Some cruisers find it advantageous to have an engine-driven source of power that is separate from their auxiliary. A small portable generator can provide AC power for tools and other appliances, but typically the DC output is minimal (8-10 amps). You can get around this by plugging in a battery charger to the AC side of the portable generator (or run the generator output into your shore power connection) and use its full AC capacity to charge batteries efficiently . Remember that while they are an efficient source of power, they are best suited for occasional use or as part of a diverse energy package. As a favor to yourself and those anchored near you, look for the quietest unit you can find and don't attempt to use it as your sole source of power. The same applies to permanently mounted gen-sets. Some cruisers need the kind of power that only a gen-set can provide. Any time they are operating you can direct a large portion of their power output into battery charging. But many AC loads are either small-to-moderate or are intermittent, and these can easily be handled by the noiseless, maintenance-free operation of an efficient DC to A C inverter. Small 200 Watt inverters can run some power tools, blenders, computers, TVs and VCRs, while larger units can provide 2500 Watts or more of continuous AC power. Keep in mind that inverters are taking stored energy from your batteries, so you must also have an adequate means of DC charging to replace that power.

Conclusion. My advice is to get up to speed with a good primer such as the Boatowner's Energy Planner, then work with a marine energy professional who can help you set up a complete energy system on your boat. To put the cost in perspective, you could get a cruising energy package that includes a high-output alternator, a combination wind and water-powered generator, a few solar panels, and basic energy-monitoring equipment for around $2500. The actual price of your system will depend on your load and personal preferences. It becomes apparent that with the right attitude, a little knowledge, and a modest investment in the proper energy equipment, you should never have to worry about dead batteries again.


Kevin Jeffrey's expertise in this field is greatly evident in his book
"Independent Energy Guide - Electrical Power for Home- Boat- & Rv".
To review and order the book, click here.



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