I have a friend looking at a used boat. Survey says one foot square soft spot in deck near hatch. I haven’t seen the boat yet but am assuming the hatch seal failed. I am no stranger to fiberglass and core work. However, I am curious what a yard might charge to pull headliner down, cut open inner layer (ceiling), replace core section, glass back up and reinstall headliner. What would be a reasonable Price reduction for him to negotiate? The more input here the better. Thank you.