• Post by Ken Hebb
  • Jan 01, 0001

Updating the electrical on a 29’ weekend sailboat

So lets talk electrical for a bit.

A 29’ sailboat like Thimble is like a weekend camper. Or a racer, a lot of people race the 29s, but that isn’t in our plans. We hope to do some weekend/weeklong vacation camping. Maybe some light liveaboard at the marina while doing boatwork on Runaway.

So the electrical needs are not as extensive as a liveaboard cruiser. Needs to have decent battery storage for lighting and appliances for a weekend at anchor and whatever. Needs to have good shore power capabilities. Needs to have a little bit of solar for regeneration while on the hook.

Because we plan on having her in a slip on shore power, I put in an isolation transformer, not just a galvanic isolator. A galvanic isolator is cheaper and simpler than a transformer, but the transformer gives us a lot more control over the feed. It will make sure that the polarity is correct. It will stabilize the voltage. And I wanted to learn about them, so that’s what I put in to manage shore power. Here is the model I went with (the 2000w model):

Victron Isolation Transformer

Shore power connection is a component that sees a lot of wear, that tends to fail and cause fires, and about which there is a lot of heated discussion. I chose this model shore input (30amp model):

SmartPlug shore power inlet and plug

The reason I chose SmartPlug is that it is the only model that has a connection surface the full length of the plug, rather than a pinch point connector. The full connection surface improves conductivity under high amperage, which means less resistance and lower temperatures. It is not a twist connection, it has a locking plug body instead. Twisting causes wear in the pinch point connections exacerbating the problems with that design.

I put in a new shore power disconnect before the isolation transformer, so I can control when the power is turned on. I also put in a new AC battery charger to handle the 200ah of AGM batteries I put in there. Here is the battery charger I chose:

Victron Centaur 12v

Victron is a great brand, especially for marine applications. And this one is ignition protected, which is important with a gasoline inboard motor. Gasoline vapor is flammable, unlike diesel where it is just stinky. Ignition protection is critical for all electrical appliances and devices installed in the engine compartment.

I also put in new GFCI controlled outlets on the outlet circuits.

On the 12v DC system, I put in a new solar power charge controller and got 2 inexpensive 100w flexible solar panels with long cords that I can plug into the fixed solar power connection I installed in the cockpit. That way it is easy to put the panels out for charging when we are off the shore power and I didnt have to figure out how to fix the panels in place somewhere on the small boat.

I also put in a battery monitor to keep track of the house batteries. So for batteries, I got 2 100ah AGM batteries, because lithium is so expensive. Way better, but too expensive. And also a lead acid starter battery. I don’t recall the specs on that one.

I separated the house circuits from the engine starter circuit, so there are two batter cutoff switches now instead of one. And I put in a battery isolator between the two systems and the alternator so that the alternator works correctly on the system. I chose an FET isolator so that there is no voltage loss like in the diode isolators, and it is simpler than a ACR. Here is the isolator:

Victron Argo FET Isolator.

I didn't change much with the main DC/AC panels. I just didn't want to get into the expense and mess of them. But I did put in a new propane monitor and control unit. Also all new LED DC lighting throughout the boat to reduce the wattage required to run them. For the lights on the v-berth and by the settees and the quarter-berth, I put in directional lights with built in USB connections, so that it is easy to charge mobile devices while aboard.

Well, that pretty much describes the electrical changes aboard. If anyone has questions or comments, I would love to hear them. Maybe someday I can get pictures put up too.


  • Post By Ken Hebb
  • Mar 28, 2021
Northbound Runaway, part 1
  • Post By Ken Hebb
  • Mar 25, 2021
All Aboard!
  • Post By Ken Hebb
  • Mar 25, 2021
Chartplotting, for real this time