I have a 2002 HC16 with plastic rudders and am trying to fix the hummmm.
I've inserted oversize nylon washers between the casting and the blades to take up some of the slack, and then tightened up the fixing bolts.
I have also sanded the trailing edge to remove the "bump" from the casting, although there was minimal "bump", but rather a bluff rounded trailing edge, so now its a smoother line with 2 mm Trailing edge.- all good ...
While doing this i noticed one side of the blade is curved in an aerofoil shape, this is on the outside on my boat. the other side of the rudder blade is pretty flat and is facing inside. i note that the rudder steering arms are both facing inwards which is correct. The rudders were fitted to the castings on the hulls when i bought the boat (second hand) and we have sailed now 3 times with terrible humming from very low speeds. It seems to me that since the outside of the hull is flat (the inside of the hull being a curve thus asymmetric) the rudder should also have the flat surface facing out and the aerodynamic profile facing inwards. Has the previous owner assembled the rudders on the wrong side? There are no markings on the rudders to say "in" or "out" that i can see. I also note that there appears to be a curve from tip to the end of the casting, ie. the rudder blades are not straight. the curve inwards.
I would much rather have new EPO3 blades, but the cost prohibits.
The rudders could easily be swapped from left to right to reverse this.
The blades are NOT the same shape on both sides, i checked and checked.
Can anyone comment on this aerodynamic/flat profile in or out ?
Cheers