Design flaw?

[Make-a-Wake]

I keep wondering why the upper rudder inlet doesnt have near enough flow to it. I have been using the speedmaster 6 1/4 straight blade rudders. Upon closer inspection of the 3 i have, i found that the both the intake slots are the same length. The top intake is so long that it almost passes the vertical bore tube. It is not capturing enough water to give good pressure as the lower one does. The slot should be made shorter as it is in the tapered rudder.............i have now ordered a tapered as i have buggered up two straight blades in an attempt to modify the slot to get more pressure...........which is when i finally realized the slot is simply cut too long.............. From photo's is looks as though the tapered has been thought out a bit better and has a short slot for the upper pickup intake thus capturing more water creating more pressure.............cost me a fair amount of $$ to figure this out. Hope the tapered works better...........looks as though it should.

[iamandrew]

is it possible that the prop is not forcing water into the holes?

[steveo]

i have alarge hor racing rudder with 2 intakes if i can remember i think that the upper intake was drilled to long and combined with the lower in take and made for not enough pressure so i jb welded the the upper intake and inner outlet and works great, try blowing through them covering the other holes it might be the same way, the manufacture might be using the same depth bit to cut both holes

[tanasit]

I cut a brass tube diagonally about the length of the intakes, filed the edges to sit flat with the rudder and epoxy it over the intake with the opening face forward of course.
I didn't feel any speed drop due to the drag but water shoot out strong.

P1140447 (Small).JPG

[don ferrette]

Take a small round file and make sure BOTH intake slots extend all the way to the leading edge, this is a 5 minute fix. I actually file the slot deep enough so that at the rudder leading edge you wind up with a small notch at each slot. The little "bump" where the machining stops at the front of the pick up slots will hurt water pickup big time at high speed.