I have a rudder from a Prindle 18 and it is noticeably different in shape.
For drilling, I have set up a jig to use one rudder as a model. They both slide snug into the jig with zero difference. Note that the locking bolts are both resting one of the wood blocks which I figure is a critical measurement. (The lines on the top rudder's leading edge were for rake measurements). I can hold a wood block at any point along the edges and the rudders match exactly. Only the hole positions are different. The chips where the rudders meet the lower transom are misleading, but top and leading edges in this area are the same.
What continues to bug me is that the rudder that matches the other P19s in the yard cannot be adjusted within the recommended rake range. The mismatched one can, and that is the one I am using the redrill the only hole that matters: The corner hole that acts as the hinge point. The holes for the locking bolts appear identical, save for the large hole providing access to the locking nut, where one is further aft than the other. Same for the other large holes that are just for knots. I've purchased new locking bolts from Murrays.
Busy this weekend, but I'll probably have her out on the water next weekend for a test.
Hobie 18 "Cheap Thrill"
Prindle 19 "Gelli Bean"
The geometry here is messed up. I understand your frustration.
Is it possible that a previous owner modified the:
1. Hull transoms (thicker or more angled)
2. Gudgeons drilled out or replaced with other types
3. Rudder casting pintle pins are different from stock?
Any of these could be the reason he ended up with a bad geometry and drilled out one rudder to try to fix it. When he found the re-drill was worse, he realized he was in over his head and sold the boat.
You have just pursued two of the other questions I had:
1. The length of the locking bolt being a strange size. The replacements from Murray's should resemble the stock ones.
2. Other holes being different. To a varying extent, the locking holes matter because they hold the locking bolt a specific distance from the casting. You mentioned that these are bigger, so possibly out of alignment?
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14