Our surveyor noted some small corrosion spots on the shaft, and wanted to pull it for a dye penetrant test. Since the boat is a single, and I plan to be outside of tow range (insurance wise anyway) I thought I'd err on the side of caution and replace it during my haul out. Good thing.
Here's what it looks like where we couldn't see it...
That big pit on the photo is well over an eighth of an inch deep.
Of course, I have to get a new prop as well, since the shaft was a crazy custom taper. I've been researching the three vs. four blades idea. The boat previously topped out at about 8 knots, but I felt it was under propped with the existing 4 blade. Most of the Google and search hits are for boats much faster than mine. Any trawler owners have experience in changing props on slower boats?