Seems like the yard would have told you if they dropped it and it seems like it would have had to really flex to cause that which would have broken something else also. Work with the obvious. It has to be fairing of some type because there is lead beneath. Fairing is generally not structural. Grind it back to see what you have. You have to work to where there is glass that is adhered to the keel or the sump. Use a plastic hammer to see if the area around sounds solid or hollow. Look carefully at the photo, there seem to be an oval that is different than the rest of the underside. You never said if the glass flared out was soft or stiff. Hos about a few more photos from the side too.