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UNDER CONSTRUCTION! --TerryKing 18:24, April 10, 2007 (EDT) This Wiki Page is intended to align with the section on the boatdesign.net Forums: CONSTRUCTION > ELECTRICAL SYSTEMS.

What it is NOT:

Really ready to use.. Much #TODO#
Coverage of shipboard electronic devices themselves
Coverage of Onboard Computer Systems (See existing Wiki Entry for this)

What should it cover?? (Please contribute!) Use the "Discussion" tab above. Or edit it yourself!

1 General Discussion
2 Electrical Safety
3 Published Standards for Shipboard Wiring
4 Rechargeable Storage Batteries
5 Onboard Power Sources
6 Onboard Power Usage
7 Power Distribution and Protective Devices
8 Shipboard Wiring
9 Example Wiring Diagrams and Physical Layouts
10 Human Interfaces and considerations
11 Power Budgeting for cruising boats
12 REFERENCES

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General Discussion

Although this is a construction-oriented page, it should be applicable to upgrading or troubleshooting existing installations.

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Electrical Safety

This is the most important part of this subject! A boat is the worst place in the world to have a fire or serious injury - you have nowhere to run, and emergency services are far away.

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Published Standards for Shipboard Wiring

Boating is a world-wide activity! We need to collect relevant standards from Europe and the Far East as well as the US.

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United States Coast Guard

U.S. Coast Guard "Boatbuilders Handbook" This is a link to a page with downloads for all the different parts of this useful publication which includes requirements for many different aspects of Boatbuilding and Safety.

Download (PDF) The "Electrical Systems" section of the US CG handbook

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American Boat and Yacht Council

These standards are guides for the design, construction, and installation of direct current (DC) electrical systems on boats and of alternating current (AC) electrical systems on boats. Download (PDF) ABYC-ElectricalGuide

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Transport Canada

Small craft built in Canada must conform to the Construction Standards for Small Vessels (TP 1332 E). Electrical systems are to be designed to meet or exceed the requirements set out in Section 8 of that document.

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Rechargeable Storage Batteries

NOTE: This is a separate category, partly because storage batteries are both Power Sources and Power Loads (when being recharged).

http://www.yachtsurvey.com/boat_battery_basics.htm is a very good discussion of storage batteries on boats, thanks to Dave Pascoe.

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Onboard Power Sources

These are all sources of electrical power that can be used to operate onboard equipment or recharge batteries.

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Propulsion-Engine-driven power sources

These are DC or AC 'generators' that are powered by the boat's propulsion engine when it is running.

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Standalone Generator systems

These are systems that combine a separate internal-combustion engine and generator for the specific purpose of generating electrical power.

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Example Generator Systems

link OSSA Powerlite NOTE: This unit not only supplies onboard electrical power but also powers electric propulsion motors.

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Windpower Systems

TODO#

NOTE: Some of the Underway Water / Wake Power Systems below are convertible to Wind Power at anchor.

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Underway Water / Wake Power Systems

Yes, here's a couple of links: (More info to go!)#TODO#

http://www.ampair.com/ampair/waterpower.asp "Aquair towed turbine for use in yachts which is the ideal power source for deep ocean cruising yachts. The Aquair towed turbine is strictly speaking a hybrid unit as it can be rapidly converted from “water mode” into “wind mode” as a a wind generator."

http://www.duogen.co.uk Another dual Wind-Water unit: "DuoGen in water mode produces a steady 8 amps at 6 knots, 11 amps at 7 knots, 16 amps at 8 knots."

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Photovoltaic Panels

A photovoltaic panel, generally just called "solar cells", is a solid-state device capable of creating an electric current from sunlight. A solar cell is little more than a very large diode, constructed in such a way as to generate electricity in response to light.

Most commercially available solar cells are based on silicon. More powerful, but also more expensive, are multilayer cells based on gallium arsenide. A typical cell you might buy for a sailboat will convert between 10 and 15 percent of the light that hits it into electric energy; more modern silicon cells can be as much as 22% efficient while a top-quality gallium arsenide cell can capture up to 30% of the sunlight (the downside being such a cell is up to twenty times more expensive than a typical silicon one). On a good sunny day, the light at sea level carries about 1000 watts per square metre of power; thus a one-square-metre panel of 15% cells will max out around 150 watts.

Silicon cells can only output around 0.7 V or so. Roughly twenty cells (give or take a few) will be wired in series on a panel meant to charge the battery of a 12 V system. The cells must be encapsulated in plastic or glass to protect them from the environment. It is the quality of the encapsulation that determines how long the cell will last (in perfect conditions, they can theoretically last for decades, if not centuries). As an auxiliary power source on a boat, they should be well secured, and the encapsulating material should be perfectly sealed to protect the cells from water, salt and impact.

Cells work best when pointed directly at the sun; a pivoting mount is ideal on a boat. They will continue to provide power, albeit less of it, in overcast or cloudy conditions. The cells are not conductive if they are shaded; block the light to one cell and the entire bank will shut off. All cells in one series-wired bank should be kept at roughly the same lighting level. If multiple banks of cells are wired to the same battery, but are in different light, maximum-power-point trackers should be used to match the output voltages for best efficiency.

Using solar as an auxiliary charger is simple and common. Using it as a prime power source is much more difficult, involving high DC voltages and huge cell areas, and is beyond the scope of this article.

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Onboard Power Usage

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Onboard Lighting Systems

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Powering Onboard Systems

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Engine Starting Requirements

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Power Distribution and Protective Devices

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Fuses

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Circuit Breakers

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"Fusible Links"

Why use a "Fusible Link" rather than a "Fuse" ?? Automobile manufacturers started doing this because high-current fuses used in earlier cars suffered from poor connections and failed from overheating.

Regular fuses "plug in" and are dependent on a spring pressure for a good connection. Over time, temperature cycles, vibration and environmental contamination, the contact between the fuse and its holder gets worse and worse and the contact resistance goes up. That causes heat, which makes contact/corrosion worse. An overheated fuse blows before its normal current rating. Replacing the fuse in a corroded holder doesn't last long. I've seen "3AG" type fuseholders on older boats that were green with corrosion.

"Fusible Links" solve this problem two ways:

1. The connection is made with a good crimp connector that makes a high-pressure large-area gas-tight connection

2. The joint is covered with a water-tight shrink covering. The newer ones have a remelted zone over the wires.

In an automotive or Marine environment this is a much more reliable years-long-life solution. Some Boats have a large (100 to 200 amp) 'fuse' near the battery that feeds a main cable to the main circuit breaker panel. Good fuses have large LUGS that bolt to lugs on the cable, with lots of pressure and area. They do not rely on spring pressure in a fuse holder. I hear they are reliable.

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Shipboard Wiring

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Size and Type of wire and cable for shipboard wiring

ABYC AC/DC Electrical Systems on Boats (Under Committee Review) Adobe PDF

http://www.editgrid.com/user/boatdesign/BoatWireSizing (An online spreadsheet for calculating needed wire sizes.) You enter wire length and operating current. (Remember to count both outgoing and returning wire length). After you enter a value and hit <enter> the table of values will update and show you the voltage drop for all the different wire sizes, and whether a wire size is safe, based on maximum current ratings.

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Mechanical considerations in Shipboard Wiring

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Marine Wiring Color Codes

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Electrical Connectors for Shipboard Applications

Electrical connectors on shipboard have more demanding requirements than those for shore applications. In particular, protection from corrosion and resistance to uncoupling under shock and vibration are important.

TODO# Discussion and images of of typical AC and DC power connectors, suggested connectors for new construction, etc.

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Typical Shipboard wiring practices

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Troubleshooting and Tips on Onboard Wiring Problems

http://www.yachtsurvey.com/ElectricalSystems.htm Tips on Electrical System Use and Maintenance - by David Pascoe

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Example Wiring Diagrams and Physical Layouts

NOTE: The US Coast Guard example "Wiring Diagrams" below are physical layout examples, and show categories of devices and the corresponding rules sections. They are NOT "Schematic Diagrams" and do not show individual actual connections. They are not adequate to define the actual detailed wiring of a boat.

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