Were you going to post some photos of your work?
Here are some I took. Can you shed any light on what I'm seeing, composition of the post and substructure?
Boat is a 1981 Islander 30 Bahama
Post measures 3 ½ x 3 ½ square. It appears to be solid but there is a cap/insert on the aft end near the top that must house something.
1 post in center (for orientation)
2 Shows approximate drop in elevation of the forward end of the sole where the posts rests.
3 Shows approximate drop in elevation of the entire forward end of the sole.
4 Underside of sole beneath post. The area in the top, center looks like some kind of repair Im not sure.
5 bottom of bilge leading forward.
6 top of post (aft end) showing cap approximately 1 wide and 12 in height. Not sure what is under it. There is some wiring running up into the mast at the forward side of the post running from under the headliner into the base of the mast.
7 mast step (for orientation)
8 shows concave shape in the deck fiberglass structure