prop clearance

[bryantee]

normally post on the raggie side. but info please.
39 ft x 11.6 ft x35ft w/line draught 4ft .single screw 320hp diesel with 26x24.5 -4- blade prop. displacement about 10 tone semi planing round bilge hull. clearance on prop about 2 inch top and bottom. how far should the rudder be from prop?
looked everywhere, no guidance, or does it not matter?
regards
bryantee

 

[omega2]

www.clementsmarine.co.uk Paul Williams is your man

 

[Jonmendez]

Agreed, Paul just organised our new props, bloody marvelous!!

 

[Tranona]

Rule thumb for prop to hull clearance is 15% of prop diameter. So for your 26 inch prop just under 4 inches. Each inch reduction increases clearance by 1/2 inch, so 23 inch would get within recommended clearance.

Never seen any guidance on clearance aft to rudder. Obviously the closer to rudder the greater the influence of prop wash when turning the rudder.