Wiring Questions

ScottG76

Petty Officer 3rd Class
Joined
Jul 8, 2007
Messages
77
Trying to rewire the boat for as cheap as possible, but still keep it safe. I will be running tach. and speedo for instruments, plus sonar, bilge, nav lights, horn and maybe a 12V accessory plug. The best way I've come up with is to use a 6 switch panel and run the horn on it's own push button switch.
I keep hearing about common points and in order to run a common ground, I would have to ground the switch panel back to the motor, but I remember reading that this would cause a corrosion problem over time. Is this true, or should I just ground it back to the battery to make it easier?
If anyone can come up with a better or cheaper way, please let me know.
 

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: Wiring Questions

Boat systems are best connected separately at the battery from the motor. The gauges should be part of the motor wiring. But that's if the background lights go on with the key. I prefer to turn them on with the bow light and that requires a ground jumper at the dash between the gauge and boat systems grounds. Otherwise gauges can fluctuate or read inaccurately. Battery connections need to be clean and tight with the motor connections going on first followed by the boat systems connections. If the trim/tilt wires connect to the battery as well, those would go between the motor and boat systems connections. Basically you go from heaviest load first to lightest load last, or heaviest wires first to lightest wires last.
 

Sig_Mech

Seaman
Joined
Jun 25, 2007
Messages
63
Re: Wiring Questions

Scott, save yourself some time and hassel down the road and use marine rated cable and wire now. Automotive wire will work but the untinned copper wire will corrode faster in a marine environment. If you look around you can find marine wire for a good price. Also, run the ground (black) wire from your switch panel directly to the negative terminal of the battery, don't ground it to the motor. This will insure a good solid ground circuit for all your electrical accessories and reduce the chance of a broken/faulty connection in the future. Try these guys for some decent prices:http://stores.ebay.com/Genuinedealz




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How come we never have time to fix it right the first time but we always find time to fix it again?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Wiring Questions

The electrical system at the console should get its +12V and Ground through the engine to controller wire harness. +12V for things you want to come on with the key generally comes off the "A" (accessory) terminal on the ignition switch. The boat manufacturer normally runs +12V and ground wires to the console. +12V feeds the fuse or circuit breaker panel. The ground wire connects to the ground bus on the panel. Here is a picture of a generic instrument panel wiring.

InstrumentPanelWiring.jpg
 

ScottG76

Petty Officer 3rd Class
Joined
Jul 8, 2007
Messages
77
Re: Wiring Questions

Silvertip, your a life saver. I came accross that drawing last night, but couldn't find it today for the life of me. Can I get away with just a regular toggle for the main battery cut, or do I have to use a heavy duty battery switch?
My plans are to put in a main battery switch, then run power to the engine and the fuse panel up front. I'm going to use a 10 gang ATC style fuse panel. I will run a two pole toggle for the nav lights, and regular for the bilge, and a momentary for the horn. Then I'll just straight wire the sonar since it has an off button. I think I want to run a line out from the nav lights to power the backlights on the instruments. I was informed to run the instruments straight from the fuse panel instead of the ignition because it could cause interference in the latter.
Sound about right? If I'm missing anything important, let me know.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Wiring Questions

You don't have to run anything from the ignition except any loads that you want to activate with the key. That would be the 12V feed to the instruments and that shows up in my diagram. Everything else can be fed from the fuse panel. The main switch is not needed. I showed it just in case someone wanted one. That switch could be located back at the battery and would be a Perko (or similar) 350A battery ON/OFF switch that kills everything except your bilge pump. If you intend to use that switch to switch power to the engine as well you need the high amperate Perko switch. If you don't want to switch the POSITIVE battery cable you can switch the main power feed with any switch that can handle 20A or so. That switch would typically be installed on the instrument panel. As for interference from or to the instruments -- that's not likely. They are very crude devices and not sensitive to "interference". I don't know what kind of engine you have but the 12V system on a 2-stroke outboard is not used to run the engine. It is used to turn the engine over via the starter. Once running, the engine does not need the battery as the ignition is powered by the stator. You are more apt to get locator interference from a trolling motor than you are the engine.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Wiring Questions

one thing Silvertip did not mention, if using 2 batteries, and you want to switch batteries, buy a constant contact perko switch. this keeps you from blowing electronics in the motor if you switch batteries while the motor is running. say your accessory battery is getting weak and you want to charge it. it is too weak to start the motor, with the constant contact switch, you can start the motor on the starting battery, and then switch to the accessory battery to charge it.
 
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