Sailboat Wood Stove I Have A Question About Rotten Wood On A Classic Sailboat?

I have a question about rotten wood on a classic sailboat? - sailboat wood stove

My son and I are renovating in 1961 gaff rig designed Crocker cut. It was out of the water and checked his ribs - 1 replaced with new cards, there are about 18 years. The bottom was painted last 2 years, and we expect that in the late spring, fully finished. I noticed an area on the outer shell where the paint is cracked and the wood is spongy surface (an area about 4 inches square) - above the waterline to the top center of the roadway. Is there an acceptable (and safe) solution to this place, to replace the tables?