Addendum - I was consulting on a Luhrs 41 a couple days ago and noticed it had the tunnel extensions and also had a prop tip to tunnel clearance...
I apologize for possibly being misleading. After looking at another 41 and several other tunnel boats, 4 inch clearance is not unusual.
Not sure if tapering the trailing edges would be necessary if taking other measures first (like the tunnel extension). You might check to see if...
I've never seen a 4" blade tip clearance in a tunnel before. We've worked on a couple of the 41's in the past and don't remember seeing that...
Ventilation and cavitation are two different things. What you describe is ventilation and yes, it does happen. The shaft alley, at planing speeds,...
