Stress cracks with a center point are often called star or spider cracks. They are caused from an inner impact. Something pushing or a hit of some sort on the inside of the boat. Most cases are caused from screws securing hardware pushing out on the gel or the edge of a bulkhead or wall pushing out from the inside as shown in pictures. Another common area with star cracks is the surrounding area of an anchor locker, where the anchor may bounce and strike the inside leaving star cracks on the outside finish. This is not damage from an impact on the outside of a hull.