A hydraulic puller is another option for the really stubborn ones, but still works better if you load it up and give the end a smack. Protect against the prop/puller assembly flying off by keeping the nut on the shaft.
".. 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"