One of the things that we're quickly finding out is that every problem or thing that seems amiss must have its root cause determined and either a fix or a plan for fixing done as soon as possible. In my case, I ignored a few warning signs that ended up with a call to an electrician and a $250 fix.

Aside from the cost, I also think now about how our bottom cleaner was in danger too of electrocution and none of us had the slightest notion of the problem.

Warning Sign Number 1 : Pedistal 20A Outlet Not Working

Last saturday I met Matt, who does bottom cleaning for Bare Bottoms Boat Cleaning Service. They've been cleaning #SVPetrichor for quite awhile and they know her well.

Matt wanted to charge his phone while he scraped the barnacle off Petrichor's hull. We tried the outlet at the dock - no power. That's ok, it's never really worked. So we tried another outlet in the back yard. It worked and so I went about my day, not thinking much more of it.

This, though, should have been warning sign number 1.

Warning Sign Number 2 : Batteries Not Charged

Yesterday, while doing our weekly boat wellness check:

  1. Check the Bilges for water level
  2. Verify All bilge pumps are working
  3. Check Battery Voltage
    • We learned this the hard way with our first set of 4D AGM batteries running down to 9V.
  4. Check for Leaks
  5. Log any smells or
  6. Start the Engine
    • Let it warm up to operating temp
    • Turn transmission forward and backward to move fluid

All this gets logged in various log books. We have:

  • Red General Boat Log
  • Black Battery Maintenance Log
  • Black Engine Maintenance Log

During the wellness check, I noticed that the battery monitor was at 12.18 Volts.

That's far lower than it should be while resting. Check back to the last log entry, the batteries were at 12.9V. I had assumed that I had just checked during a float or equalization period.

Something's Wrong, No Shore Power

Now that the batteries were down to 12.18V, that indicates something's wrong.

First thing to do is to verify that the charger's on. It isn't. There's also no power coming from Shore Power.

I slowly trace things back one piece at a time all the way to the dock's shore plug to the house's breaker panel in the garage.

The 50A breaker had been tripped. Ah, must've been a fault of sorts. My first thought, "I hope there wasn't a short somewhere on Petrichor."

I flip the breaker off, then back on. In a second, the breaker trips again. I try one more time and this time, I hear a bzzzzzzz and Nina, who's in her office in the house, tells me that the lights were flickering. Ooooh man, not good.

I unplug the shore power cable and try once again to see if the problem is with Petrichor or not.

bzzzzzzzz trip... Good that it's not a problem with Petrichor, bad that we're now without power and the batteries are slowly draining.

I immediately let Nina know that there's a short somewhere in her house. As she calls up her electrician, Mike, I pull the batteries off Petrichor. The anti-sieze compound and dielectric grease I had used for the batteries worked well! Despite there being a tight solid connection, it came undone easily without any damage or corrosion anywhere!

Petrichor has 5 batteries in 3 banks (Listing of battery sizes can be found here):

  1. Starter Bank = 1X BCI Group Size 35 Sealed Heavy Duty Marine Battery
  2. House Bank A = 2X GC2 6V Flooded
  3. House Bank B = 2X GC2 6V Flooded

The starter bank was ok since it's isolated via an ACR until after the engine starts.

The two house banks, though, have various always on safety electronics wired to it (battery monitors, bilge pumps, anchor lights). They will altogether slowly drain the batteries to 50% within 2-3 weeks if left alone without charging.

At 62 pounds each, 90º temps, and about 80% humidity... lugging these guys off one at a time - though only taking about 30 minutes - was pretty tiring.

I took them inside and wired them up to a 3 bank charger that'll be replacing our current 2 bank charger.

With that out of the way... Mike starts educating me about 2 phase AC power.

There's your problem right there

What was most interesting was his order of operations for isolating the fault.

Here's a quick and dirty schematic of power going from the home's breaker panel (A); to the first junctiom box where wires exit the hose (B); to a junction box at the dock entrance (C); to the shore power outlets at the dock (D); and then finally to Petrichor (E).


White is common/neutral. Black carries 120V at 50A. Brown carries 120V at 50A.

This allows the Shore Power Outlet (D) to have 2 plugs that'll put out 120V at 50A each. This is enough to service two boats - one docked on each side of the dock.

This also gives you the flexibility to combine the two hot wires for 240V if needed.

So here's what Mike did to isolate the problem:

  1. Disconnect (D)-(E)

This verifies that the problem isn't with Petrichor.

  1. Disconnect (B)-(C)

This will test to see if the short is between the breaker (A) and the (B) OR between (B) and the Shore Power Outlet (D).

Mike then used a continuity tester to check whether there was a short between the black and brown wires. He found that there was a short somewhere between the junction box (B) and (D).

  1. Disconnect (C)-(D)

This will test to see whether the short is between:

  • the junction box (B) and junction box (C), or
  • the junction box (C) and the shore power outlet (D)

With (C)-(D) disconnected, it was found that the short was between (B) and (C), the two junction boxes... where wire is buried underground. Mike had anticipated this but was hoping that it wasn't so.

He popped open the junction box (C) at the dock entrance and... there's your problem right there:


I didn't snap a photo of this before Mike drained all the water and cut out all the rotted wiring.

It turns out that water had filled the junction box and the wire going out of it towards the shore power outlets (D) had been skinned off.

So once enough water entered the box, it shorted everything out.

The home owner was very lucky in that the rains in the previous week probably prevented the short from starting a fire.

The diver was lucky that he wasn't electrocuted.

$250 of new wire and large blue wire nuts later, the problem has been fixed.


The blue wire nut is what it's supposed to look like.

The other wire nut is what two 50A circuits shorting look like.

Luckily, no additional damage had been caused. But lessons learned: always check for stray current in the water and don't ignore small clues and things that don't work or aren't working right.

Find root cause; fix it as soon as practical.