Gettin' Ship Shape

Boat/US Magazine, July, 1999 by John Greviskis

If you've read my column before, you may have noticed that I try to inject a little humor when I'm writing about boat improvement projects done over the years on my television show. However, this time the subject matter is serious. I will be reviewing electrical wiring for your different D/C systems on the boat.

Now I know what you may be thinking. Electrical wiring? That sounds intense! But really, it's not as difficult as you might think.

I recently rewired a 1976 21-foot Seabird. When I looked up under the dash inside the center console, it looked like a rat's nest. Wires were going in every direction. The previous boat owner added a stereo and wired it straight to the battery without going to a distribution panel, like a fuse block or circuit breaker panel.

I then saw that the VHF radio was done the same way; then a bilge pump, then this, then that. It literally looked like spaghetti strands up under the dash. It was also all 18-gauge wire, something I highly advise against. The minimum gauge wire you should ever use on a boat, even for a low-voltage situation, would be 16-gauge wire.

Now let's talk about selecting the proper wire for your project. First off, what color should it be?

It is helpful to use the international color code system that the American Boat & Yacht Council (ABYC) has developed for wiring a boat. ABYC has assigned certain colors to different wires that hook up various accessories around the boat for fast and easy identification.

For example: A pink wire is for the fuel sender. So, whether you're in Berea, OH, or Berea, Greece, a marine technician knows that when he's dealing with a pink wire, he's working on the fuel sender, if it's a proper installation.

Without having a system like this, the technician would have to individually check each wire until he came across the one for the fuel sender. Not only does the color code system simplify repairs, but it also saves time (and money) in the repair shop.

Secondly, what type of wire should you be using? I only use tinned multi-stranded copper wire on a boat. The number of strands and type of insulation depend on wire size but should be specified as marine grade. (Solid copper wire is never used on boats.)

Finally, you need to take a hard look at the gauge of the wire you'll be needing for the project. The gauge is the thickness of the wire, and there is a very complicated mathematical formula that will tell you precisely what is safe to use. It's based on voltage draw, circular mills and amperage. It's way over a lot of people's heads so I've posted a chart on the "Ship Shape TV" Web site for anyone to look at.

For a safe installation, you need to be concerned with what amperage draw your accessory requires and how long the wires need to be in order to hook it up. If the run is too long and the draw is too much, the wire could heat up, catch on fire and burn your boat to the waterline. And it's here that most do-it-yourselfers get into trouble.

When estimating the wire's run, most people measure from the accessory to the battery. For example, say it's 10 feet from your bilge pump to your battery. Well, most people would think that's a 10-foot run. Wrong! It's a 20-foot run because you need to measure the length of the wire to the accessory and back again. So the bilge pump that's 10 feet away from the battery requires a 20-foot run and, in many cases, a 20-foot run requires a heavier gauge of wire.

Also, all wires should be run in one piece, not spliced, and should be supported a minimum of every 18 inches with nonmetallic clamps or straps. Your terminal connectors should be ring- or captive-spade and never wire nuts. ABYC also specifies how connections should be made.

John Greviskis is the executive producer and star of "Ship Shape TV."