Category: Milestone 7 – DC/AC electrical systems

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Building a custom fridge box inside a sailboat: Step 1 – Preparations

This past week preparations were made for building a new fridge box inside the boat. There has always been a big empty space beneath the kitchen counter that has been hard to reach ever since the stairs were moved there. The fridge box will be placed in that empty space and will be accessible from the top. Although in this case there really was no other option, it actually always a good idea to have the fridge opening at the top. This way the cool air inside the box will not fall out when you open the door. The plan is to insulate the fridge with a minimum of 10 cm insulation to further increase the efficiency of the fridge box. In some places even more insulation will be used, especially in the small space where the freezing section will be.
To compensate for the immense thickness of insulation there will need to be a lot of empty space available underneath the kitchen counter. Therefor all unneeded planks and beams were removed and some much-needed cleaning and painting was done to prepare this space for the placement of the new fridge box.
The holes that were made to access some of the bolts that go through the hull of the boat were also closed off again. Plus some of the 230 volt wiring was redone now that those parts were easy to access.


The cooling unit used to cool the fridge box will be the Isotherm 3251 ASU Self-Pumping Water-Cooled Component System which is one of the most efficient systems out there, while also being near silent (no spinning fan). With this system the sea water-cooled skin fitting/heat exchanger replaces the air-cooled condenser and cooling fan that normal systems use. The through-hull fitting of the kitchen sink was replaced with this special fitting last month when the boat was on the hard (out of the water).
Isotherm 3251 ASU Self-Pumping Water-Cooled Component System

The building of the actual fridge box will follow in an upcoming post. Till then, fair winds and following seas…

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Installing solar panels

The first two solar panels have now been installed and are performing tremendously well.
I first hooked them up in series and later in parallel for testing purposes and it seems the best option (for how the panels are placed at this time) is connecting them up in parallel.
My record to date (on a particular sunny day) was a little more than 60 Ah from one panel alone.
Of course this was in perfect conditions and the average Ah a day will be far lower, but this already exited my expectations about how much energy one panel would be able to produce in one day.
See the pictures below for more details about the panels I used. On a later date I will be writing up a more detailed blog post about how I tested my setup and why I choose parallel hookup instead of in series.
Also created a new battery enclosure for the starter battery to make more room for the two 200 aH batteries that will go alongside the starter battery.
Plus redid all the wiring to and from the batteries to make the setup more compact and less messy (which can, and will still be approved upon)

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Reinstallation of the 12V DC and 230V AC electrical systems aboard the Seadog

It turns out that buying new solar panels and a big battery bank, plus all the other electronic equipment that is needed aboard a boat (like battery charger/inverter, multiplexer, GPS, plotter, log depth sounder, etc.) costs a lot of money. Especially if you’re talking about marine grade products.
Just kidding, of course I knew the amount of money all that stuff was going to cost me, but I always try to spend as little money as possible (while still trying get the best possible quality). Luckily my parents recently got a boat that had a pretty good DC/AC inverter that they didn’t use. Which also came with a big battery which was still in perfect condition. Although the inverter was rather old (and not a pure sinus inverter) I will be able to use my induction cooktop with this installation, so for now it suits me just fine. So after some measurements and planning of where all the future electronic equipment needed to be, I grabbed a piece of plywood, made a little shelf to support the inverter and screw the inverter into place.



After hoisting in the battery and connecting it up to the charger/inverter and the switch panel, I finally had a working 12V service battery that could be used to power all the electronics aboard.
Now it was time to test out the depth sounder and log that came with the boat. Turns out they both still work!
Sadly the two repeater displays (one for inside the cabin and one for outside in the cockpit) where not functioning anymore, but I did find an article online that describes how to fix that problem. I did try to repair them right away, but that did not work out. For now, I won’t be needing those repeaters anyway. Because I bought a multiplexer with wi-fi, which enables me to send all the navigational data to my iPad (or any other laptop, tabled or smart phone device). The old GPS unit that came with the boat does work though. Which means I can use that GPS unit with its own antenna, to get a good GPS reading into the navigation software on the iPad. I quickly made a simple navigation station from another piece of plywood, so I could hang all the navigation equipment in one place.


So I did have to buy some new equipment like the multiplexer, a DC to DC converter (to convert 12V to 20V for powering my monitor and laptop with DC), and an automatic switching relay (which enables the service battery to be charged when the motor is running). Also I bought a rotary switch to manually switch between shore power and inverter power (for the 230V AC system) and installed a marine grade RCD (residual current device) safety switch.
It’s a good thing I went and installed that new rotary switch, because the old setup where I had a normal AC switch installed to turn off all my AC power almost set the boat on fire!
Apparently that switch could only handle up to 10 amps, and aboard the Seadog that appears not to be enough, which caused that switch to cook itself!
That only goes to show that if you do everything yourself you better be knowing what you’re doing (especially with electrical systems). Luckily for me this didn’t end with my boat in flames. But I did learn my lesson and started to read up some more about electronic systems and safety aboard sailing vessels.
This new switch can handle up to 30 amps, which is more than enough, so that will not be happening again. I would really recommend everyone who is doing their own 12V DC or 230V AC installations aboard to buy and read up about electronics aboard boats. It really helped me understand the inner workings and gave me the confidence that I knew what I was doing. There are some pretty strict rules to follow especially with electrical system aboard a boat, which might not always be what you would expect. Please note that in some of the pictures the cables are still looking very messy, but believe me when I say that when all work was done everything was properly connected and fixed tightly and properly together.

I also bought and installed a waterproof USB socket that converts 12V to 5V to up to 2+ amps, so it can be used to power the iPad from the cockpit. The iPad also has a waterproof casing now, so navigation can be done from the cockpit on the iPad even in the pouring rain (let’s hope that does not happen to often). And if the iPad ever fails, it’s not to big a problem, because the beautiful Sestrel Moore compass is now also installed back into place.