[golden_fox]

Hi Everyone!

Can anyone give me an indication as to what is a recommended minimum clearance between the propeller blade tip and the bottom of hull? And if the propeller is in a tunnel, does this vary?

Thanks a lot and appreciate any input.

[CODOG]

I would suggest a generalised tip clearance of 1/6th of prop diameter, for both a tunnel and non-tunnel application. Also, I'd use the same ratio of clearance as a minimum from trailing edge of prop blades to leading edge of rudders.
I've seen successful installations with more and less clearance, but the above is a good starting point. Too little clearance is worse than too much usually.
Are you buying a prop / props off the shelf or purpose made ? Is this a tunnel application ?

[Booker]

15% of prop diameter is a good rule of thumb.