I had a couple soft spots in the deck of my Tsunami under the pedestall seats.I had to recore them,and it's a fairly easy fix.
I cut the top layer of glass off,using a circular saw,set to about a 1/4"depth.
I then removed the piece of deck,which in my case was about 24 x 36 inches on each area.That now exposed the core,which was plywood directly where the seats mounted,and balsa core on the rest.
Again with the saw set to a shallow depth,i cut thru the core,(it was 3/8"),just to but not thru the bottom piece of glass.
I chiseled,scraped,and ground out the wet rotted core until i hit dry material.
After i prepped the bottom layer of glass,i laid up a piece of 1-1/2oz mat to it,and let it kick a bit,then took some 3/8" marine plywood,and bedded that into the mat,by applying a slightly thinned hull and deck putty to the faces of the mat and plywood.
I placed a whole bunch of 12lb downrigger weights on the plywood until the resin/putty cured.
When it was done i laid up a layer of mat on top of the repair.
At this point,i think i'm going to put a layer of mat over the whole deck,and mask off sections leaving a white border with areas of gray or tan non skid.
The bottom layer of glass was extremely thin and several holes where the seat bolts were drilled,went thru the glass into the stringer boxes.Also i found vacant holes drilled into the boxes,(maybe for the foam filler)and i think thats where some of the water saturated foam in my stringers came from.
Maybe these pictures will help.
The first one is after i had already cleaned up the area and put down a layer of mat,and the last is one layer of mat over the repair
