A few weeks ago, while digging around in some old boat parts boxes, I found the stuffing box from my old Catalina 36. It was sitting in the parts box because I had chosen to replace it with a PSS Shaft Seal to make my bilge totally dry. Today is a rainy Sunday and I though it would be a good time to rig it up in my garage and photograph how to replace the flax packing inside one of these "work horse" style stuffing boxes and add it to my "Boat Projects Gallery".
For illustrative purposes I cleaned the stuffing box of it's oxidation and grime with my drill press and a wire brush. I used a piece of 1" diameter stainless steel as my makeshift prop shaft to complete the picture and present this as it would look inside a boat.
In this picture what you are actually seeing are two nuts not one. The larger of the two is where the flax resides. The thin nut, on the left, is the locking nut. Once re-packed, & properly adjusted, you lock these nuts together with two large wrenches.
If you don't lock these nuts down tight enough, meaning the nuts are each tightened in opposite directions against each other quite tightly, you run the risk of the big nut backing its self off the threads when you put the transmission in reverse. There have been more than a few boats sunk by improper tightening of the stuffing box nuts! Just ask the Boat US insurance division.