Archive for the ‘boat’ Category.

Stabmixer – Electric Outboard Project

Ever since I was a kid, i wanted an electric outboard motor to use with a light rubber boat (without a hard floor). I actually even started experimenting when i was 12, but that didn’t work out at all.

Now, many years later, I wanted to give it a try again, my goal was a lightweight electric outboard, driving a chain inside a tube down to the propeller. Unfortunately, it all went wrong after I’ve made a prototype that was running the chain directly through the water. It worked so well, that I’ve decided to keep the chain outside. What I built is good for more than 1kw, but my intex excursion has it’s limits at around 6kph, which requires roughly 400watts.

The part’s I’ve used are:

Battery: 12s4p 18650 High drain (powertool) cells.
Motor: Chinese no-name Hub, good for about 1000w continues
Gear Ratio: 22×14
Propeller: JXF 15×13 / 381 x 330mm
Other Parts: Aluminium Rods, Steel Plates, Road frame parts, Buttom Bracket, Bolts, Nuts, Washers, Stem, Handlebar.

Be sure to check out the videos:


Seafarer D800 Echo Sounder repair

On our boat, we have an old Seafarer D800 echo sounder. The device slowly stopped working two years ago, the depth it was able to measure went smaller and smaller, in the end it couldn’t measure at all, even if the depth was only two meters.

I’ve missed to take pictures, but the repair was very simple. There are to caps inside, at least one of them is 1uf 63v, electrolyte was leaking on one side, so I was pretty sure that it’s not good anymore. I’ve decided to replace it (only had a 1uf 50v available), and this did the trick. While I was at it, I’ve also cleaned the mode button (realized, that it was stuck), and cleaned the two pots (both are working much better now).

It is now working as it should again, I was able to measure up to 80 meters (limited by the depth, not by the sounder)!

Happy boating, the season just started here.


Eberspächer heater 24V to 12V conversion

The previous owner of our boat installed an Eberspächer Air heater, which was meant for a lorry, and therefore 24V. Our boat only has 12V Batteries / Alternator. As far as I know he used another battery in series with the auxiliary battery to power the heater, but this battery obviously wasn’t charged when using the heater – I didn’t like that solution, the heater wasn’t used for about 10 years, and now I’ve decided to build a solution.



The heater has a small controller unit + the heater itself. My idea was to find a 12V to 24V step up converter, and run everything on 24V. This didn’t work out, as I didn’t find an affordable 12V to 24V converter, the one I bought said 150W output power, but that just isn’t enough for the initial glow.

2nd idea:
I thought, why not just replace the glow plug, with a 12V version (didn’t know if it exists back than), and use a relay to switch a 12V line with the 24V from the controller unit.

Doing it:
At this point I’ve decided to unmount the heater, as i needed to find out what kind of unit I have, and which glow plug I actually needed.

What I found was even better:
There’s a huge resistor (or call it a spring) in series with the glow plug – the glow plug is actually a 12V plug, you just need to rewire it to not use the resistor, and install the relay as mentioned above (I obviously don’t know if this is with all the Eberspächer heaters, but it’s worth looking).



Open controller unit:


Controller unit with attached step up converter + relays:





Close-up of the modification:

The yellow line goes to the glow plug (already connected directly on the picture, the yellow line in the background goes to the resistor and back):

Having a cold beer on a boat.

I prefer having a cold beer when I’m on our boat, but since this is usually on the sunny days, the performance of our fridge (Waeco CF-18) was too weak to cool one down in a short time (temperature in the cabin goes up to ~35° C if the sun is burning down).

I’ve been thinking about some kind of a GSM-based remote control, and actually found a nice product called microguard. The product seemed perfect, relatively cheap, easy to implement, available, but there was no time-out that could be set. Even if I have a separate starter-battery, it was key to find a solution that turns off the fridge after a given time without user interaction. Luckily, the guy who runs microguard was very cooperative, and added a timeout feature for me (and everyone else of course).

The module now turns on a relay for two hours after it’s been called from my or one of 4 other predefined phones. this is a bit on the short side, but I can live with calling twice.

This is how my installation looks:

From left to right:
Charge split diode / Rear side of main switches / Fridge fuse / Microguard module with relays, cables, mounted on an a plastic case / RedBull cup as holder for a Siemens S45.
The Cat5 network cabling goes directly to the voltmeters on the dash, this was made to show the exact voltage without loss due to load on the cabling.

As mentioned before, I have two separate batteries the starter is a traditional lead/acid battery, and the domestic is an AGM type, which allows deep cycles.

This is how the battery compartment looks:


The switches on the left are starter / jumper / domestic. This allows maximum flexibility. The domestic main switch actually doesn’t kill the microguard / fridge, so it can be off, and I can still call the fridge.