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Watt a Boat: ‘Sqoop’ Gets an Electrical Makeover

In February we shared Jay Whitlan’s story about the transformation of his Laguna 26 into a square- rigged sailboat, which he then named Sqoop. Here Jay recounts the work he did to upgrade Sqoop‘s aged electrical system to a safe, modern setup.

Sqoop on the water
“I find the square sail to be effective over a wider range of downwind angles than a spinnaker or wing-on-wing configuration.”
© 2022 Jay Whitlan

When I purchased Sqoop, the electrical system was what you’d expect to find on a 35+-year-old boat with multiple owners — a tangle of chaotic wiring and a schematic that made little sense. I’ll describe three issues I discovered and then dealt with as a DIY’er, while referencing Don Casey’s Sailboat Electrics Simplified. Hopefully, none of this will sound familiar to you!

During the pre-purchase survey, I was pleasantly surprised to find that the boat had a functioning 1500W inverter; being able to run a drill, air pump or similar AC appliance when away from the dock can be quite useful! The inverter was connected to the battery with a fairly short length of beefy, one-gauge cable, meaning both the ampacity and the voltage drop of the circuit were more than acceptable.

Unfortunately, neither the positive nor the negative cable was restrained correctly, and both were routed through a single (un-grommeted) hole in a fiberglass bulkhead. Most concerningly, I couldn’t find any circuit protection after tracing the entire wire run! Here’s the potential nightmare: The positive and negative cables chafe on the edges of the hole, the insulation wears away, the positive cable grounds to the negative cable, and the massive surge of current starts a fire that burns the boat to the waterline.

To avoid this unpleasant scenario, I added an ANL fuse block (with a 120-amp fuse) to the circuit, as close to the battery as possible, drilled a new hole in the bulkhead, installed grommets, separated the positive lead from the negative, and secured all cables with clamps or tie locks.

Much-needed circuit protection for the inverter.
© 2022 Jay Whitlan

A few days later, while trying to make sense of the wire nest surrounding the main DC bus bar, I noted a fairly large 6 AWG cable running from the bus bar to a fuse block with a 100-amp fuse. The return ground cable was 8 AWG (smaller than the positive lead), which was puzzling, since 8 AWG cable is not rated to carry 100 amps of current. Before doing anything, I replaced the 100-amp fuse with a 40-amp fuse; now at least the fuse will blow before the wire starts melting! Next, I had to figure out where this cable ran to, and what in the heck it powered. So I started tracing its path through the innards of the boat.

Eventually, I found the other end over by the nav desk. It terminated with a pigtail containing two small 18 AWG wires, each powering a low-current device. Why were these large 6 AWG/8 AWG cables powering a combined circuit load of less than five amps? I’ll never know for sure, but perhaps the boat once had a smaller inverter and this was the power lead?

Anyway, since this high-load circuit was already installed, I figured I might as well make use of it. I rerouted the cables, crimped on some new ring terminals, and connected them to a remote fuse block that I installed under the nav desk. All the devices at the nav station (VHF radio, desk light, CD/stereo, DC outlets) were then wired to this fuse block, allowing me to remove oodles of old wiring that ran cross-cabin, and enabling the future addition of voltaic goodies (an AIS receiver is on my wish list).

Remote bus for nav desk accessories.
© 2022 Jay Whitlan

My last uncomfortable discovery — the boat’s AC system had no shorepower disconnect switch. Although not (yet) required, I installed an ELCI breaker in the V-berth. This kept the breaker within the required 10 feet of the shorepower cord receptacle (located in the anchor locker). The ELCI breaker will protect the boat from a faulty dockside power source, but more importantly, it will prevent Sqoop from causing an ESD fatality.

ELCI breaker panel.
© 2022 Jay Whitlan

It’s great having all these electrical toys onboard, but in a marine environment, and on an older boat, it pays big seamanship dividends to ensure things have been installed and wired correctly.

To view the table I used to conduct a load analysis and organize the electrical system, click on the link: Sqoop electrical system


  1. Jim Quanci 2 years ago

    On your inverter circuit protection… folks might consider a battery terminal mount fuse block… easy to install as you can just use the existing cable (no extra cable to make up)… and zero inches between the fuse and the battery (ultimate in safety). Not sure when these sorts of “on terminal” fuse blocks came on the market as they were unknown to me until during my last survey my keen Surveyor suggested it. For example Blue Sea Systems MRBF Surface and Terminal Mount Fuse Blocks

    • Jay 2 years ago

      Yes, that looks like a great solution Jim! I’m not sure it would fit into my rather tight battery compartment, but getting the distance between the battery and circuit protection down to zero is certainly ideal.

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