The little 3D printed tug that could
If you’ve ever spent time observing what goes on in a seaport, you must have seen tugboats at work: those little boats that push, pull, and push huge cargo ships around the tight nooks and crannies of the harbour. They achieve this through extremely powerful engines placed inside their relatively small hulls; their power-to-tonnage ratio can be ten times that of most commercial vessels.
A hardware hacker who enjoys building equally powerful machines is [Luis Marx], and it’s perhaps no surprise that his latest project is a real tug. Living on the shores of Lake Constance in southern Germany, [Luis] enjoys spending time on the water, but is tired of the drudgery of paddling. Local regulations restrict the use of outboard motors but allow the use of R/C model boats; therefore, building an R/C tug to move around the lake should be perfectly legal.
Although we do not know if the Lake Constance police will follow the same reasoning, [Luis]The model tugboat is a marvelous piece of engineering. With a design inspired by 3DBenchy, the standard 3D printer benchmark that anyone with a 3D printer has likely printed at some point, it took around 30 hours to create the parts plus a generous helping of epoxy resin to render all waterproof. A powerful lithium-ion battery drives two brushless DC motors designed for racing drones, which together can produce nearly a kilowatt of power.
Unfortunately, that turned out to be much more than the little boat could handle: any attempt to use it would simply cause it to jump out of the water and land on its back. Setting the motor controller to around 50% made it much more controllable, but still strong enough to move around [Luis] on his stand-up paddle. The boat is controlled by a bespoke handheld R/C controller which communicates with the ESP8266 inside the boat via WiFi. Without a rudder, left-right control is achieved by simply halving the power of an engine.
A fully charged battery provides enough juice for about 40 minutes of pulling, so it’s probably a good idea to bring paddles anyway. Unless, of course, you also have a self-contained, solar-powered tug ready to come to your rescue.