The correct position for installing a surface drive system:
The nut on the propeller blade should be positioned 10mm below the boat's transom extension line. However, for some light-loaded high-speed boats, the position may vary slightly, such as being 20mm below the transom extension line.
The main engine and the transmission shaft should form a straight line, not a large angle. If the engine is revved up and the prop system remains unchanged, the universal joint cage of the coupling will have an angle instead of a straight line, which can cause damage to the coupling cage over time.
While tilting the engine, the half-immersed propeller and the shaft should also be tilted at the same angle to form a straight line.