This was a cut out from the factory to allow the water lines to pass under the ring frame. It is my conjecture that the ring frames were originaly designed to be placed over coring in the hull. There is no coring in the area of the ring frames on all of the 46's that I have been able to inspect, so the water lines have no problems passing through this area anyway. We took the opertunity to strengthen the ring frame by filling this in.