While trying to loosen the lock nut on my prop shaft stuffing box I’ve discovered that a PO has been too aggressive with a chisel and left the lock nut split. I thought all I needed to do was change the packing, but now need more than that. This would obviously be best done while hauled out, but have any of you tried to temporarily pack the prop shaft from outside to replace the entire stuffing box while in the water? I’ve heard it’s possible, but a failure would be catastrophic.