Re: Fiberglass buildup around rudder stuffing box
First you need to determine (if you can) if the leak is coming in around the rudder stock/shaft, or if it's leaking alongside the stuffing box tube past the fiberglass patchwork.
If it's the former I see no need to grind glass except to free up the lock nut. It's certainly not necessary if a simple repack is in order.
If it's leaking past the patchwork glass that's another issue altogether. Are you able to determine what's what on that score?
Your biggest obstacle to a simple repack is the need to remove the Universal joint to get enough clearance to back the nut out and replace the packing.. looking at that arrangement it's easy believe that it's never been properly done. Very tight clearances on all counts, it won't be an easy job, no matter where the problem actually lies...
Pretty boat, btw!, and yes, Welcome to Sailnet.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"