The propeller is touching the black plastic cap.

For cruising hydrogenrators 300W, 600W and racing hydrogenrator Class 40

If the propeller can touch the black cap of the hydrogenrator, it means that the spring washer of the propeller shaft has been over-pressurized. That can happen when transporting the hydrogenerator, or if the shafts gets a small shock. 

To get the shaft in the original position, the easiest method will be to screw the propeller with small coin between the base of the propeller and the black cap. It will pull the shaft a bit out, and release the tension of the spring washer. it can be done when you will install back the propeller on the shaft. 

Then, while sailing, the propeller will anyway exerce a drag force that will keep the propeller away from the black cap.

A picture to explain, here it was done with 2 washers : 

• The propeller is installed with the washers and the M5 screw of the propeller is tightened. It pulls the shaft out.
• The M5 screw is lightly untightened and the 2 washers are released and removed.
• The M5 screw is then re-tightened