Jet-powered RC boat with 5-inch FPV drone power (jet-powered sprint boat)

After seeing a video of an American sprint boat online, I vaguely modeled this boat. The currently popular kart boats have a longer aspect ratio, so their directional stability is relatively better. It took two iterations to finally get the stance right.

The power system uses the common 2306 motor for 5-inch FPV drones and 4S batteries ranging from 850 to 1550 mAh.

The jet pump is still based on this one: 24mm jet thruster for 5-inch FPV drone power (bucket reverse) - Free 3D Print Model - MakerWorld, with an extended nozzle modification.

The external rotor motor doesn't dissipate heat very well on the boat, so I simply drilled a small hole on the side of the water-cooled motor mount facing the motor. You can try it with a hot thin iron wire. This allows water to directly pour onto the motor. At the same time, an internal drainage port was made on the pump body, and the intake port can be fixed in the area inside the cabin most prone to water accumulation.

Two 9g servos, Silver Wing or PTK size. I used 7452 servos, disassembled the casing, filled the circuit board compartment with 704 sealant, and applied grease to the output shaft of the gear compartment for simple waterproofing.

The receiver, with at least three channels, was also waterproofed using 705 silicone sealant.

You can directly buy a water-cooled ESC; about 40A should be enough. I simply wrapped mine in heat shrink tubing, sealed both ends with 704 sealant, and then put an outer casing over it. Alternatively, you can add another layer of heat shrink tubing, insert two soft tubes into it, and then seal both ends for simple water cooling.

The screws are mainly M2 self-tapping screws, 6mm and 8mm long.