Probably Polarity


I need your assistance with my boat wiring.

I have changed trolling motor batteries in my boat and since, I have burned 2 twist plugs. My cables aren’t marked so is it possible I may have crossed them or is that something that would cause my dilemma.

What could be causing me to burn the plug? It has a 4 wire Marinco outlet.

Thank you


On a 12/24 marine electrical system, wiring the batteries is critical. Use a meter (not a test light) to determine if the polarity is correct and the battery cables are correctly connected.

The circuit protection in the positive leads at the battery should trip before you burn up the plug. If you don’t have fuses or breakers at the battery, now is a great time to add them.


Aluminum Fuel Tank Grounding


I am told a copper ground wire should never be connected to a aluminum gas tank. Is that correct. I ask because my new tank has a ground tab welded on it.


Captain Ron

Hi Captain Ron,

Copper wire – either tinned or not tinned – is the marine standard for boat wiring.

When grounding a metal fuel tank, the main requirement is to keep the resistance between the fuel tank and the boat’s ground to one ohm or less.

Here is ABYC standard H-24 says:


Each metallic fuel tank and metal or metallic plated component of the fuel fill system, which is in contact with the fuel, shall be grounded so that its resistance to the boat’s ground is less than one ohm.”

Hope this helps,


Self Starter


I hope you can help me. I am trying to figure out if my ignition switch is faulty.

It is a 4-post switch. One post says IGNI, the second says ACC, the third says BAT and the center one says nothing but there is one wire which goes to the starter solenoid.

Is the the center one supposed to go to solenoid? The reason I’m asking is because I am trying to find a short in my system and the engine tries to start by itself when I turn on my master switch without turning the key.

Please help.



Hi Mark,

The last wire should go to the starter solenoid, but usually passes through a neutral safety switch first.

I would start by removing the wire for the key switch, if that solves the problem, then replace the key switch.

The next area I would inspect would be the wires on the starter.

Hope this helps,


First Trip Failure

Hi Kevin,

I recently bought a 2000 Sprint Fish and Ski.

During the first 15 minutes of taking it out the first time, the radio stopped which caused me to further investigate. None of my accessories were working at that point except the gauges. I checked the fuses and they all appeared to be good. The battery has a good charge.

I took a piece of wire and jumped it the the bilge pump switch over to the battery and it worked that way. To me it appears to be the power switch but I’m very green when it comes to boat wiring.

Please help.


Hi Ralph,

The boat engine systems are typically separate from the boat accessory systems.

If all accessories have quit, it is either the main power feed or the ground. I would check the main fuse at the battery and its connection along with the ground connection for the accessory harness.

Good luck,


Turn of the Screw


I have a 2000 Four Winns.

It has dual trumpet horns installed, one of which was not working when I bought the boat in 2005. The second horn failed last year.

My voltmeter shows 12+ volts when I press the horn button but when I hook up a new horn, nothing happens. If I direct connect the horn to the battery, it sounds. I’m confused because the voltage is there.



Hi Stephen,

This is a simple fix.

Carefully remove the sticker on the rear of the trumpet (it probably says AFI). Turn the exposed screw slowly until the horn sounds.

Hope this helps,