Re: propshaft thru hull
Looks to be a combination cutlass bearing sleeve and stern tube.. 'stern tube' might be the term you're looking for but a google search didn't turn up anything helpful.
1984 Fast/Nicholson 345 "FastForward"
".. 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)