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RC Rowboat

A small LEGO rowboat with motorized oars and a remote control using Circuit Cubes.


Completion date: 23/07/2021
Power: electric (Circuit Cubes)
Remote control: Circuit Cubes
Dimensions: length 18 studs / width 24 studs / height 9 studs
Weight: 0.105 kg
Suspension: none
Propulsion: 2 x small Circuit Cubes motor geared 2:1
Motors: 2 x small Circuit Cubes motor

I always found the tiny LEGO rowboats from Pirates sets (among others) very cute and I have long wanted to make one of them motorized and remotely controlled. Unfortunately given the size and weight of LEGO electronics this was out of the question, and then Circuit Cubes arrived. They were still a bit too large for the smallest LEGO rowboat so I’ve tied a LEGO pontoon. I’ve quickly found out that the amount of weight, the height of the center of gravity and the speed at which the oars work are crucial because if the boat rocks too much sideways, it will take water and sink, like my pontoon did. Undeterred, I have found a rare, larger LEGO rowboat and installed another version of the mechanism in it, this time with reduced weight and lower oar speed. And it worked!

The entire creation was fairly simple, there were only two challenges. The first was preventing the oars from rotating along their own axes, so they would remain “vertical” and not “flat”, because a flat oar doesn’t provide any propulsion. I have solved this problem by putting this piece on each oar and then connecting it with a steering link so that it would always be facing in the same direction as the oar moved. The other challenge was transferring the drive from the motors to the 24t gears independently, because it required two 12t gears and there was only room for a 3 studs long axle, which didn’t allow using two independent axle pins, one for each gear. I’ve eventually placed a regular Technic pin in two adjacent Technic bricks, put a 3L bar inside that pin and installed one 12t gear on either end of the bar. It worked, the gears were able to rotate independently and remained firmly held in place.

This was a very simple creation built to relax, but it was quite enjoyable and provided its own challenges. And rowing around my bathtub was just as fun as I have anticipated.


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