Practical small powerboat maintenance by Berrien Allen

Author:Berrien, Allen
Language: eng
Format: epub
Tags: Motorboats
Publisher: New York : Hearst Marine Books
Published: 1995-03-15T00:00:00+00:00

ELECTRICS

sible to keep the corrosion from beginning all over again.

Troubleshooting with a DIVIIVI

Most times the above actions will disclose the problem. If they don't, it's time to bring out your testing tools. While it's true that you can do some low-voltage troubleshooting on a boat with a simple test light, a meter will allow you to do so much more that it's a near must. For my money, the only meter worth having is a digital multimeter (DMM). Suitable ones range in price from $30 to $150.

Before you start electrical troubleshooting, there's one more nearly indispensable tool. You can make one or buy it. It is what I call a pig-sticker probe. They're called dissecting probes and can be bought at a well-stocked hobby shop. Or you can make one yourself by drilling a small (one-sixteenth inch or so) hole in the end of a four-inch piece of one-quarter-inch-diameter dowel. Insert the eye end of a good-sized sewing needle into the hole with your needle-nosed pliers, and your pig-sticker is ready for action. This probe is handy because you can insert it into solderless butt connectors to make electrical measurements without cutting the connections apart. Of course, first you'll have to slice the heat shrink tubing off the connection. After making the necessary measurements, you can reseal the connections with a few coats of MDR's Liquid Electric Tape.

Continuity Testing

Most electrical troubleshooting can be accomplished by checking for continuity (a fancy name for a complete circuit). You can do this with a simple, self-powered test light or your meter's ohms function. In continuity testing, the electricity is furnished by the meter. Therefore, the first step is to shut off the power at the vapor-proof switch before you start. (If you need to check the run between battery and

the vapor-proof switch, unhook the positive battery terminal.) If you're using a conventional meter and don't shut off the power, you can ruin your meter. DMMs (digital multimeters) are goof-proof by nature; they just flash their digits if you do this.)

Suppose you suspect that one of the magnetic breakers has tripped. You can find out by clipping one test lead to each of its terminals, and setting the meter to its ohms function (sometimes labeled with the Greek letter omega: Q).

When the breaker is in the "off" position, the meter should indicate an open circuit. If it's an analog unit, the needle won't move. A digital meter will say "OL" (overload) or something to that effect. When you switch the breaker to its "on" position, the meter should indicate a very low resistance. The analog meter's needle will swing over almost all the way; the digital meter's display will indicate a resistance of a few ohms. (For a demonstration of this, touch the two test probes together; that's what continuity looks like.)

You can use continuity (ohms) testing to check switches and components, such as fuses and lamps. Any of those devices should have a resistance of only a few ohms. If an incandescent lamp

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