Boat Craft Q&A: Pulling Wires
Want to replace your old stereo with a brand-new one? There's an easy way to sort through all those colored wires.
by David G. Brown
Q: I own a 1999 runabout, and I want to replace the stereo, but the existing
wiring is different than the new unit I purchased. Does someone make a wiring harness for boats
that’s similar to cars?
— Jim Read, Grapevine, TX
A: You’re referring to adapter cables and plugs designed to allow installation of
aftermarket stereo equipment into different brands of automobiles. No such adapters are offered
specifically for use in boats. The problem is that a bewildering variety of stereo units has gone
into boats over the years. This has prevented a standard system of plugs or wiring color code from
evolving in the marine industry.
Replacing a stereo unit starts
with “doping out” the existing sound system wiring. Each wire must be traced to find its purpose.
This can take some time. There will be up to a dozen wires, depending upon the number of speakers
and power options. Each wire will have color-coded insulation. For instance, the insulation may be
red, blue, purple, etc. Also, some wires will have a white stripe in addition to the base color.
Don’t try to memorize the existing color code. Nobody can remember all of the colors and purposes.
Instead, write down the color code of each wire and what it connects to. Consider writing the
purposes of the wires on masking tape “ flags” for quick reference. Here are some typical color
codes for aftermarket automotive stereo systems:
Power Wiring:
+12-Volt Ignition Power — red.
+12-Volt Battery Power — yellow.
Ground Wire — black or spade stud on case.
Speakers:
Left Front (-) — white with black stripe.
Left Front (+) — white.
Right Front (-) — gray with black stripe.
Right Front (+) — gray.
Left Rear (-) — green with black stripe.
Left Rear (+) — green
Right Rear (-) — purple with black stripe.
Right Rear (+) — purple.
Note that speaker wires are either positive (+) or negative (-). This refers to the
"phasing" of the speaker. If you install speaker wires out of phase, some of the sounds you
normally hear may cancel each other out or be distorted. Fortunately, no harm will be done to the
speaker or stereo if you install the wires out of phase.
In automobiles, the stereo’s power is drawn from the ignition switch, so the unit turns on
and off with the key. On boats, however, it’s more desirable to wire the stereo to the battery
switch’s output side. Doing so allows the unit to be used whether or not the engine is running.
Larger cruisers usually have a designated breaker switch for the stereo on their 12-volt power
panels, but smaller bow-riders may require running a separate wire. If so, this wire requires fuse
protection at the battery switch end.
Many automotive stereos have built-in clocks and other features that are “always on.” They
need a constant, uninterrupted flow of 12-volt power running directly from the boat’s battery.
Current draw for these “always on” functions is extremely low, so the stereo is unlikely to drain
the starting battery in this way.
It may not be mandatory to connect the “always on” power wire. However, the functions it
feeds won’t operate correctly if you don’t. Check the owner’s manual for information about any “
always on” functions in your stereo and what happens if they aren’t connected. The “always on” wire
(usually yellow) should bypass the boat’s battery switch and go directly to the positive (+)
terminal on the battery, and it must include fuse protection at the battery end.
It’s almost always necessary to cut the old connector plug(s) off the boat’s existing stereo
wires and splice on new plugs to match the new stereo. Do this one wire at a time to avoid
confusion. Double-check each new connection to be sure it’s correct. Crimped butt connectors are
satisfactory, but they should be marine-rated for maximum corrosion protection.
When the job is finished, fold up the paper on which you’ve written the wiring color code.
Tape it to the stereo case so it will be available next time you need to tinker with the wiring.
Q: I want to add a GPS, but the 12-volt panel’s accessory breaker only has one
terminal, and it’s being used by a fishfinder. Can I connect two wires to the terminal without
splicing?
— George Beauchamps, Troy, MI
Special connectors allow you to plug your GPS and
fishfinder to the same terminal without splicing.
A: There are so-called “multi-stack” connectors available for just that purpose.
They have a female push-on connector with an added male spade. Install this connector on the new
power wire to the GPS. Then, plug the fishfinder +12-volt lead onto the spade lug. The two wires
then attach to the male connector on the breaker switch. Ancor sells these in a package of three
(part #230612) through most big-box marine retailers.
Q: I like to boat on a river and run with my docking lights on so I can see logs
or anything else floating in the water. My friend says it’s against the law to use those lights
when I’m not docking. Who is right?
— Clyde Dillon, St. Louis, MO
A: There’s nothing illegal about using docking lights to spot driftwood. However,
the “Rules of the Road” does say that you can’t display any lights that either obscure or can be
confused with your required running lights. On many boats, the docking lights are mounted so close
to the red and green sidelights that the colored lights are virtually undetectable from head-on. A
boat with this configuration would be illegal to operate for long periods of time on open water
where it might meet crossing traffic.
Also, bright white light reduces the skipper’s night vision. Objects such as boats crossing
your path outside of your docking lights may be more difficult to see. The traditional advice is to
protect the skipper’s night vision, unless you know there are floating dangers or deadheads in your
path. Then, a spotlight or docking lights can help to spot dangerous objects and avoid any
problems.
Q: My 1983 fishing boat has “soft” stringers. The surveyor says the wood inside
the fiberglass has rotted. I’ve been quoted a repair price that’s nearly the value of the boat.
Other than the stringer problem, the boat runs well, and it’s a good fishing boat. We had hoped to
keep the boat until the economy is a bit less shaky. What can we do?
— Sam Miller, Euclid, OH
A: I checked the book value of your boat, and it looks to me that if you intend on
staying with boating (and fishing), it may be a good idea to fix the stringers. In good condition,
your boat is worth about $15,000. Most banks will loan at least $7,000 to $10,000 on this boat,
which is more than enough to cover the cost of the repairs. However, right now, the market value of
the boat is zilch because of the soft stringers. In simple terms, borrowing $10,000 to fix the boat
may return $15,000 in equity when the job’s done. That’s a 50-percent return on the investment.
The equity of the repaired boat could become a large part of your next down-payment on a new
boat when the time comes. Of course, all this assumes the old boat is in decent cosmetic shape, and
the engine is still strong. As a rule, boats that need only a single major repair like your
stringers are worth the money. However, if two major items are needed, the total cost of the
project often approaches or exceeds the value of the boat.
On the other hand, junking a boat isn’t easy. The hull must be stripped of everything that
can be removed. Then, it’s cut up into pieces that will fit into a dumpster. Most trash haulers
have additional charges for putting an old boat in a landfill, and the cost of this work will vary
depending upon the area of the country. Expect to pay from $700 to more than $2,000. The marina or
company doing the work will sell the metal parts for scrap and keep that money as well.
Send your BoatCraft Q&A questions to Dave Brown c/o Boating World, 2100 Powers Ferry Road,
Atlanta, GA 30339. You can also e-mail your questions to
editor@boatingworld.com. Due to the
volume of inquiries he receives, Dave Brown
will be unable to answer every question.