Hi Flashman!

If your propshaft has M4 thread, you can also try the hydroprops from the Graupner K-series.
The suggested 42 mm Kyosho prop is a bit too large for my liking, start with a 36K and work your way up, on my mono1 I use a 37,5K on a 600 motor and 7 cells GP3300, anything larger makes the motor smell funny...., so keep an eye (and finger) on your motor!

Greetings, Jan.