between the upper stock and rudder stock. Upper stock is tapered, cut with a keyway, and threaded on the end. It slips through the lower bronze stock, with a tapered socket and keyway, the upper slides through, and is secured with a 3/4" castle nut. It's a massive affair of which I'm intimately aware of have(I've disassmbled/re-assembled a few times).

Last season, I found some play in the joint that revealed that the key stock(only 5 years installed by me), had worked some play into the joint. I took my problem to the metal shop at Rockport Marine and they advised me I needed to hand fit the keystock to the slightly enlarged (over 50 years use) cut keyway, in the bronze to eliminate any rocking.

The upper rudder stock raised, I took my time with a file and vise to shape and oversized piece of bronze to fit snuggly in both the upper and lower stock keyways. When the castlenut was "yarned" tight, all was one at the joint. Still,...as I put some severe use on that joint in some very boisterous conditions this season, I'm anxious to see if any play has developed. Haul out will tell me if the new custom key stock fit is the full fix, or some milling of the slots should be looked into.

That play could go undetected for decades of coastal use. On the other hand, it's possible, it could degenerate into a problem in short order in rough conditions. Hard use will expose many flaws in a boat.

I was at a friends boat this fall at haul out, that lost it's propeller. Once hauled, it was evident the prop was spinning free. Upon pulling the prop, it was clear the key stock had sliced off between each key way slot. Yikes!