Replacing back to back seats?

[Damontis]

I recently purchased a 1989 maxum 1700/xr and need to replace the back to back seats. The wood is mostly rotted on the original seats. The problem that I am having is I cannot seem to figure out how to take the base out of the boat. I can't find any screws or bolts that is holding it down to the deck. Does anyone have any ideas before I have to get the saw-zall out?