Since the ducks were afraid of motor noise (or maybe the boat speed) I’ve bought another motor. For some reason I’ve decided that 500 RPM should be enough. While I waited for the motor to ship, I’ve assembled a simple device to measure RPM. Arduino, led and photo transistor was all that I needed. If I place the propeller between the led and photo transistor, arduino can count how many times the blades interrupt the light and compute RPM from that. And I’ve found that the original motor produced about 24000 PRM. Needless to say that when I’ve installed the new motor that boat hardly moved. But the motor was much quieter, so I liked it anyway.
Now instead of fast scary boat I now had non-moving innocuous one. Could ditch the motor altogether I guess.
To remedy that I decided to replace the propeller as well, as the original one was quite small. The biggest one that I could fit was 52mm in diameter. Any bigger one would collide with the steering mechanism. The original propeller was about 38mm.
Now the boat can move, though is still very slow. At least the ducks are content.
Also, by chance I’ve got a very cool gull photo.