Generally speaking, the bigger hull blocks become, the larger grows the possibility of local break or buckling during turnover and transfer by means of cranes. Prior to constructing our first ULCC of 400, 000 D. W. T., authors calculated the stress distribution in 430-ton deck block which was assumed to have the probability of local damages. The deck block was substituted by a plain frame structure for the convenience of calculation which was carried out by our computer program STAN II. In accordance with the above results and our long experience regarding VLCC, authors reinforced some local structural members of the deck block and measured it's actual stress distribution during turnover. As the result, we found little difference between calculation and measurement.