Hello. I have a 1995 18 ft Astro bass boat 150 mercury motor, and I have dry rot on passenger side of boat about a foot foot section if that . I put gloves on and stuck my hand through and touched another piece of wood to the left of it and that piece was was rotted also. How can i tell if i have just those 2 spots bad and how can i get to it. I don't really know about boats designs and so on,but i am pretty handy and know my way around a ruler or 2.