pull the bow rail.
from the looks of it, the deck coring may be bad, as there is a circular crack at the stanchion base.
once the rail is off, inspect everything. if the core is good, simply grind out the cracks, patch the area, match the gel and anti-skid, then reinstall the bow rail.
if the core is bad, you will be cutting a section of the deck up to replace the core
what kind of boat?