Rudder problem

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Friend has recently bought a large old timer, small trawler - launch tripper, used for both at some stage.
Boat is out of water on cradle.

Problem 1, rudder has jammed, being trying to free it with muscle and sprays, no joy. So he has decided to take rudder shaft out.

Hull
.............................................
[... ...] Nut
| |
| | Shaft
| |
| |
|__|__________ rudder top plate

Rudder top is attached to shaft with what looks like a stainless pin, but it doesn't go right thru shaft, so we wondering how to extract pin and take plate off.
We have removed the Rudder itself, only the top plate is still attached.

Any ideas ?

Its all unbolted up top and we have started the nut under the hull.

sorry about vague diagram.

Pics????

[obbayer]

Considering the rudder shaft should have been surrounded by packing flax I would have to wonder what made it freeze up so bad.

How about just unbolting the whole thru hull assembly and dropping it all out and then do further inspection and dissasssembly on the work bench,