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Module 1 Batteries

Module 3 Engines
Module 4 Lightning
Module 5 DC Systems
Module 6 Electronics
Module 7 Radios
Module 8 Water
Module 9 HVAC
Module 10 AC Power

All About Boat-Electrics

Module 102 - Boat Wiring and Boat-Electrics Systems

At the completion of this subject module you will understand the application of Wiring Rules and Recommendations(ABYC, ISO, Lloyds); Basic electrical theory and the use of test instruments; How to plan electrical systems, perform load calculations, select cables, calculate voltage drop; select the required protection systems (fuses and circuit breakers). You will understand wiring installation practices, panels and switchboards, metering and grounding, and how to perform basic maintenance and troubleshooting on all boat-electrics systems.


Whether used-boat or new-boat when it comes to electrical systems, good planning revolves around attention to detail and there is a logical sequence for determining the various parameters. Whether you are buying a used-boat, or a new boat, you need to plan carefully before changing or upgrading boat-electrics. A concise and realistic load analysis must be carried out to determine the battery requirements, and this must consider normal operational loads as well as intermittent ones. When this is completed a suitable battery type must be selected, and whether flooded cell, Gel or AGM it will have to be compatible with the calculated discharge rates. Learn about boat-electrics here.

While capacity uses AmpHour (Ah) capacity and discharge rates over nominal 20 hrs rates, the charging is based on the charge acceptance rates, therefore a suitable alternator rating and smart charging regulator must be selected.

Questions of failure modes and the provision of redundancy within the circuit design are also essential. This may entail the installation of dual alternator charging systems, the separation of starting and charging systems, and provision of backup supplies and splitting loads into dual circuits. Every boat-electrics system should have a "Plan B" built into the design. Learn about boat-electrics here.


Introducing needless complexity into electrical systems is unfortunately common and unnecessary. When you buy a used-boat or a new boat, you have to start with what is installed, and in most cases you inherit something you don’t like. It is common to see boat-electrics installations that are in effect test beds for a yacht owner’s own application of ideas and theories, and a voyaging yacht is the last place to be experimenting. The most reliable yachts have simple systems designs that exclude complicated switching, systems interlocks and unnecessary automation. Accepted design principles are available from ABYC, Lloyds and others that consider reliability and failure as basic parts of the rule and recommendations philosophy. Which Wiring Rules What are the various wiring rules in use around the world, and which do you use. Learn about boat-electrics here.


Reliability depends on sound design and planning, and is worthless if the proposed equipment is not up to a good standard. The old adage of "the poor man always pays twice" is very true when it comes to yachts. Cheap lights, switches, circuit breakers, and other "bargains" often end up failing after short operational lives. When you buy a used-boat you often end up with another person’s problems. Learn about boat-electrics here.

The overall percentage costs of electrical equipment as a portion of the entire boat costs are relatively small. It is important to purchase and install the very best equipment that you can find or afford. Select equipment that is marked with the various approvals for marine use and those rated for the maximum environmental protection ratings. Always select tinned copper cable, the initial extra cost is worth the savings in long term reliability. Most used-boats and many new boats now have tinned copper. Learn about boat-electrics here.


Wiring and equipment must be properly installed if they are to stay operational. The layout of equipment must consider environmental factors such as exposure to spray and water. This installation layout should also consider cable routes with respect to these factors, along with minimizing exposure to mechanical damage. Where possible the cable runs should be made as short as possible, not just for limiting voltage drop but to reduce interference either into other cables or from other cables.

Good boat-electrics practices consider the segregation of high and low power equipment cables from data and signal cables. Given that some 85% of failures are directly attributable to failures in connections, performing as few as possible, and ensuring they are properly done is an investment in reliability. Those connections exposed to water such as bilge pumps should be properly made and sealed. Where connections must be made they should be in a quality junction box to protect against water. Where cables pass through decks or bulkheads they should transit through cable glands. Learn about boat-electrics here.

Wiring Boat Trailers

Wiring your boat is one thing, but making sure you wire your trailerboat trailer wiring is another. They are both 12 volt but they are very different. Go to the various trailerboat boat wiring pages for correct information

Basic Boat Trailer Wiring Part 1How to connect up your Australian boat trailer electrical wiring. Basic Boat Trailer Wiring Part 2 How to connect up your United States boat trailer electrical wiring. Basic Boat Trailer Wiring Part 3 How to connect up your European and British boat trailer electrical wiring


Electrical systems can be summarized in one concise statement, "Do it right, and do it once!" Whether it is a used-boat or a new boat, carefully assess the systems installed and make changes based on the results. Get boat-electrics right!

Useful Links and Resources

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Alaska Hunting Guides - Arctic North Guides is a true full service Alaska Hunting Guide & Outfitting service operating Alaska. Hunting trips in two locations including the Brooks Range Hunting and The Alaska Peninsula.

Montana Elk Hunting - Yellowstone Fly Fishing Pack Trips - Elk hunt with one of the most experienced guide services in the business. Pack into a secluded backcountry camp on horseback for a 7-day trip, to hunt in some of the most beautiful mountains

Alaska Fishing Lodges - Halibut - Salmon - On the west coast of Prince of Wales Island at the base of the Klawock River, the Fireweed Lodge is a full service fishing resort offering guided salt water and self-guided stream fishing packages.

Oregon Fishing - Rogue River Fishing - Guide Service on the Rogue and other Southern Oregon rivers for the finest King Salmon and Steelhead fishing. Experienced in helping plan your fishing trips to Oregon's vacation paradise.

Salmon & Steelhead Fishing, Idaho & Washington - We specialize in professionally guided salmon and steelhead fishing adventures in Alaska, Oregon, Washington and Idaho. With over 30 years of professional full time guiding experience.

Tillamook Bay Fishing - Oregon Fishing - Tillamook Bay has been a consistent producers of big king salmon on the west coast. Its tributaries, Miami, Kilchis, Wilson, Trask, and Tillamook Rivers make it a serious king salmon destination.

Fishing Gear - Local reports world wide help anglers learn where the fish are biting, what is working best, and communicate about their local fishing area. Ssarch on fishing locations or types of fish to catch

Haleiwa Hawaii Fishing Trips - North Shore - North Shore Fishing Trips at Haleiwa Hawaii, Bottom Fishing, affordable Hawaii Fishing Trips. Low cost Hawaii Fishing Trips

Hawaii Shark Adventures - Hawaii Shark Encounters gives you the opportunity to experience the beauty and excitement sharks in their native waters. Proud partners in a worldwide effort to improve the understanding of sharks

Canada Fishing - Experience heart-pounding Canadian Sportfishing action. Master Guide with thirty years experience gives all out effort. Pinpoints the best time and place to fish

Fish Finders - This is the only place you can find comprehensive reviews of hunting and fishing gear submitted by actual users. Search our database of user submitted reviews for all kinds of outdoor equipment

Alaska Fishing Guides - Our Alaska salmon fishing and trout fishing guides take you to the real Alaska where you can experience the exilarating thrill of fishing for Alaska's wild and abundant Salmon and Rainbow Trout

Kenai River Salmon Fishing - Alaska Fishing - Experience a trip to Kenai Alaska for the highest quality Alaska King Salmon Fishing. Kenai Alaska is the home of trophy King Salmon and one of the worlds most beautiful settings.

Hawaii Fishing Charter - Experience heart pounding big game sport fishing. Oahu, Hawaii - with Capt Rusty Spencer: blue marlin, wahoo, mahimahi & yellowfin tuna. Friendly experienced crew aboard well equipped 31-foot Bertram

Alaska Fishing Lodge - Finest Alaska fishing. Our top Kenai River guides specialize in fishing for trophy Alaska salmon, wild Rainbow Trout and also Alaska fly out fishing. We offer the Alaska fishing trip of a lifetime.

Alaska Salmon Fishing - One of the oldest outfits on the peninsula. Well established, family owned and operated charter fishing. In this business, experience counts, over 15 years of knowledge and expertise to make your trip a success.

Hawaii Sunset Cruise - Observe Hawaiian Humpback whales while sailing the waters of the famous North Shore, the least crowded whale watching spot on Oahu. Our Small groups give you a personal and up-close experience

Oregon Salmon Fishing - Providing quality fishing trips on inland and coastal streams and bays in Northwest Oregon.

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