Electrical connections on boat


Old 06-01-10, 01:47 PM
Thread Starter
Join Date: Jun 2010
Location: USA
Posts: 1
Electrical connections on boat

Our boat is a 1984 16' center console fiberglass Wellcraft powered by a 1990 70hp Johnson motor.
The fuel tank is under the forward seat of the small console, and I have been advised that the battery should be installed under the console toward the stern from the fuel tank.
The fuel tank has been removed, cleaned, and the fuel gauge sending unit replaced, with a new fuel gauge mounted on the console.
Other than the control box with ignition, the tilt control, and the fuel gauge, we have a bow and stern light, a bilge pump,
a depth finder, a compass, and a spotlight (which has its own on/off switch) to be wired.
All wiring has been removed.
It is my understanding at this point that the new electrical harness and the tilt control harness will be wired directly from the battery, and I view the ignition as the switch for that.
Stated differently, it appears to me that the lights, bilge pump, depth finder, compass and spotlight should be wired through the fuse box, with switchs for the lights and bilge pump. Am uncertain whether switches are needed for the depth finder, compass and spotlight. It seems that a switch will be needed for the fuel gauge, but again, am uncertain.
I have studied the fuse box to a certain extent, and understand the concept of device negative to fuse box, and device positive to switch to fuse box, but am somewhat stymied by whether switches are needed for other than the lights and bilge pump.
Finally, no battery was with the boat when we bought it and so I have no idea where it was mounted. The heavy battery cables we received are 10' which leads me to believe they should be run from the console to the stern - the question is to what? If these cables go only to the control box, and if it is okay to mount the battery under the console, we certainly do not need that length. And the best I can figure, the new
wiring harness will feed from the battery to the motor.
I hope I have presented this concisely enough that you can give me an opinion.
Regardless, once all is done I am going to have circuitry and connections checked by a professional before turning a key.
Thank you for your advice.
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Old 06-02-10, 05:13 PM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
first off welcome to the forum. I might miss something so feel free to ask more questions.

The 10' cables should go from your battery directly to your motor. If they reach and you have room under the console is a good spot for the battery.

The rest of the boat electrics will also be hooked to your battery.
Since you're starting fresh I would run a breaker at the battery with a short 6 gauge wire to a battery shut off switch, then to a fuse panel. From the panel you can run each component on it's own fuse. From the panel run wires to switches then to the actual component.

At the key switch there will be a purple wire, this is powered when the key is on, Use this to power your lights for gauges it will help with any condensation that may build up.Also power your fuel gauge with this.

For your T&T power that from your fuse panel.
Old 06-03-10, 03:53 AM
Join Date: Apr 2007
Location: Near Buffalo, NY
Posts: 4,239
The negative wires from all devices are commonly connected to a terminal block which is connected with a (10-gauge or heavier) wire directly to the battery. No switches, fuses, or circuit breakers should be installed on the negative wiring.

Use only wiring and components that are desigend for marine environments.

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