Glyn’s Boat Wiring


Please could you comment on the boat wiring diagram that I’ve drawn up.

It includes:Wiring-diagram-300

  • Twin Verado outboards
  • Shorepower
  • Generator
  • House batteries.

I’m currently trying to wire up a new boat here in Oman (no technical expertise available) and I’m really concerned about dangerous AC currents floating around the boat whilst my family swims.

Please could you have a look and give me your comments as I’m no expert at this?

I know that I’m missing an earth wire from the fused junction!

Any input from yourself will be most welcome.

Kind regards


Hi Glyn,

Very nice diagram!

I have a few comments.

  • Add circuit protection at the source of power for your 24 hour emergency bilge pumps fuse panel.
  • Add circuit protection at the battery switch for your main DC distribution panel
  • Your shore power ground (green) needs to run to your AC ground buss
  • Your galvanic isolator is connected between your shore power inlet and the AC ground buss in the green wire

Also, I would consider not connecting the 3 bank inverter to all 3 banks. Instead,

  1. Connect two legs to the house battery bank
  2. Connect one leg to the port engine battery bank
  3. Connect 0 legs to the starboard engine battery bank

This would allow you to completely drain your dc system with the inverter and still be able to start your starboard engine and charge the system through your automatic charge relay

As drawn, your boat’s AC electrical system should be shock proof.Wiring-diagram-2-250

Most marine AC problems occur when the DC ground is not connected to the AC ground. If you boat has an AC fault to a DC component, the common ground will allow the circuit protection on your AC distribution panel to trip and not energize the water below.

Please send me pictures of this project,


Hello Kevin,

Thanks for your input.  I’ve updated the pdf (in case you want to use it)

I’ll take pics and send them to you. But, it might take a while as I’m in Oman and it’s a real struggle to source the various electrical components. Nevermind the marine grade wiring (at the local marina they have a bad habit of using domestic grade wiring).

That’s why I’ve elected to attempt all this myself.



Pontoon Rewire Advice?


I am trying to rewire my 1991 pontoon boat. I have made many attempts on the internet to find schematic pictures or drawings. Do you have any suggestions of where I can locate them?

Thank you for your time,EZ boat panel rewire system



Pontoon boat wiring schematics are very rare. Most people either start rewiring their boat one wire at a time or purchase a pre-fabricated harness that has wiring for all the components they require.

Our partners at EzAcDc make a great Pontoon Boat Wiring Harness that has connections for navigation lights, docking lights, boat horn, courtesy lights, livewell pump, and pontoon stern light.

This harness will connect directly to any of their marine electrical panels.

Besides the wiring harness, EzAcDc also sells a clever kit to rewire your boat’s original OEM electrical panel. This is one of their best selling items because it makes this previously crappy job considerably easier.

Hope this helps,


Go to Ground


I know little about boat wiring so please forgive my ignorance.

My brother has a 22 year old 17′ VIP inboard motor boat with an intermittent electrical problem. The navigation lights and bilge blower were not working.

While we were messing with it we quickly hit the trim switch to lower and raise the motor – immediately the navigation lights and blower started working. 1987-VIP-17
Later, they stopped working and again we hit the trim switch to lower and raise the motor – again the lights and blower started working.

The boat wiring is generally not in good condition. There are splices in the wiring everywhere, but all the connections appear to be okay. The horn and the radio work fine all the time. The battery is good.

Any thoughts you have would be greatly appreciated.



I would start at the battery and work my way to the components.

The common link between the engine trim, the blower, and the navigation lights is their ground system.

  • Clean the battery connections. Replace wing nuts with locking nuts.
  • Clean the ground connection on the motor – opposite end of negative battery cable. Ensure all connections are intact.
  • Check the connections at the blower and lights to make sure they are intact and making good contact.

This should solve your problem,


The sound of one horn clicking…


Saw your site too late, I wish I had seen your recommendations and bought from EzAcDc.

My Problem: I am replacing a rusty dual electric horn on our 44 sportfishing boat. Should be easy, right? Buy new AFI dual trumpet horn, install and rewire to old connections, push button, hear horn.

Well, this is a Carolina boat and it has many interesting little nuances that we have discovered. One of those is the wiring to the horns. I always wondered why the horn sounded weird. Now I know, only one horn (of the pair) was wired.
There is a large gauge wire running to the tower station (white, black and green). This was wired directly to the horn. Two wires ran to the white and only one of the horns blacks went to the black. Therefore only one horn sounded. When I wired both to white and both to black, the dual horns sound for a second, then neither sounds. It makes what sounds like a click, however and that’s all. I pulled the wiring apart and both horns work individually, just not together. I am guessing that they couldn’t figure it out/fix it or didn’t have time to figure it out before delivery. EzAcDc is proud to feature AFI boat horns, the marine industry's finest

What are your thoughts?



When the second horn is connected, there is too much of a voltage drop in the horn circuit to power both horns. This could be caused by a poor connection or too small a wire in circuit. It is also possible that the horn button is causing the problem.

Check all electrical connections. Try connecting the new horn directly to the horn button. Test the horn at all possible locations in the horn circuit and you will find the problem.