We have recently come to recognize that there is a possibility of very severe stress condition of the transverse webs in the top side tanks, through the experience in damages caused at the said parts of the two O. B. O. carriers which were built in our yard about three years ago. Attaching importance to the damages, we measured stresses at the top side tank of the similar ship which was going to be delivered, and made structural analysis as well, to make clear the cause of the damages. As a result of such measurement and calculation, we found that the calculated stresses were almost equal to the actually measured ones. Further, we also made calculation on the damaged ships and could conclude that the cause of the damages would be the high stress caused at the damaged parts when the ship heavily heels and the stress corrosion of the members caused thereby.
