300MM Pump-Jet Kart Boat

The boat fits a 3mm shaft + printed propeller. Bearings use 3x7x3 x2 or 3x7x3 for the rear + 3x9x3 for the front. Plastic bearings or bushings are recommended.

Alternatively, a 2mm shaft + finished toy propeller can be used (26mm two-blade + 28mm three-blade). I used 3x5x4 powder bushings.

The shaft seals are uniformly 3x9x3 for the output shaft and steering shaft.

Output shaft 2mm round or 3mm D (can be manually adjusted), length around 100mm.

Steering shaft 3mm D-axis (can be manually adjusted), length around 100mm.

M3 nut 3x5x4.5

Cooling tube bore 4mm, fits 4mm copper or stainless steel tube. The left outlet is a bit close to the steering seat, the copper tube can be slightly bent before installation.

The motor mount is designed for 380-395 series motors, and the locating pin for the hull is 3mm.

If the printed propeller hole is a bit small due to material shrinkage, you can use a 3mm drill bit to remove the boss, and a tight fit with a 3mm shaft is also acceptable.