Hi Azcat,

I'm not sure if my knowledge /experience is helpful to you since my personal experience w/ NACRA/Performance products is limited to the P-19 ... but here is what I've learned

I suspect your rudder blades are the same as the blades retro fitted to the P-19 replacing the short square tipped (bottom) blades origonally used on the P-19. They do look identical in the pic's.

First, I have had (4) new blades split from the rudder head (top) down due to "sheer" loading generated internally from blade deflection. As the blade is loaded due to side-slip the blade deflects in a curve ... one side is in compression the other is in tension ... this results in internal "sheer" loading that splits the blade from the top down. I fixed the blades by using (20) 3/8" wooden dowels installed w/ epoxy from side to side ... sanded off the gelcoat .... using 2-layers of 4"wide Fiberglass tape I sealed the seam and then reskinned the rudderhead completely. I have had no more problems w/ the rudderblades. So you have a good idea w/ the dowels but I think it solves a different problem

Now I have fixed several centerboards and rudderblades that have "met the road" ... ie:having been dragged down the highway. The repair process basically startes w/ hollowing out the inside of blade so you can make and install a new inner core first. You can make a new core from wood (I like cedar)or foam. Shape appropriately and install into hollowed out section ... make sure the new core is "bedded" well using epoxy w/ thickners. Next taper the existing outside skin for 4-6" ... then reskin and fair as required.

Now it is counter-intuitive but the internal loading is least at the bottom of the blade vs's the top as the blade acts as a lever arm/cantilever and the internal loads are greatest at the head.

Now, w/ all that said I would suggest a different path to a solution ... do you have a "new" spare rudder blade? If you don't I would purchase one from NACRA as I believe they come w/ the holes located and drilled properly in it. Or contact them and ask if they could provide you w/ a template/tracing of a new blade properly locating the holes. I would compare the new to the old ... fix the old and save the new. It is always good to have a spare ...
just think about how much $$$$'s you have invested in a weekend just to have it wasted due to a broken boat on Saturday afternoon and no replacement parts. (I always carry an extra rudder blade w/ me for whatever boat I'm racing that weekend)

I'm wondering are you trying to fix something the wasn't broke??? I asked this as you are comparing (you friend's) daggerboard boat to (your) non-boarded boat ... how was the helm on your N5.7??? If it was neutral or had slight weather helm you are OK. It has been a long time since I "tuned" a Non-boarded boat ... but if I remember correctly it is a balance between mast rake and rudder blade rack to get the proper feel on the helm. The method Jake, Karl and others suggested for using a straight-edge to check the rudder rake is the method we all use. Unfortunately the measurement is unique to each model boat due to the angle of the transome and measuring point locations so none of us can give you an actual measurement.

Oh, I did have to "notch" my rudder blades slightly to get them to lock down properly as they were hitting the corner of the transome and bottom of the boat. But now after adjustment/fitting my P-19 has a neutral helm to weather and downwind under spin w/ proper sail trimming it is neutal also. So there is a sweet spot ...


Good Luck and Happy Holidays
Harry Murphey
H18MAG/P19MX w/spin