Slamming load on a very large floating structure with shallow draft

The objective of this paper is to estimate the slamming load acting on a pontoon-type very large floating structure with a shallow draft. Experiments were carried out using elastic models with different rigidities in regular waves. The results revealed that the slamming load was strongly influenced by the rigidity of the model. The conditions under which slamming occurs depended on the extent of the bottom emergence and the velocity of the relative wave height at the bow of the model. These results were related to a simple procedure for estimating slamming load.     

Stern waves consisting of forward-oriented breaking waves and the remaining following waves

When a ship with a wide, immersed transom stern runs on a deep draft, forward-oriented wave breaking often occurs just behind the transom stern. In such conditions, stern waves can be considered to consist of two main components: the forward-oriented breaking wave and the remaining following waves. In our previous study, which was the first part of the present study, we developed a method to treat the forward-oriented breaking wave, and have clarified that it has a scale effect and its resistance coefficient decreases with an increase in the size of the model ship. On the other hand, the study also indicated that the height of the remaining following waves increases with an increase in the model ship size. The purpose of this paper is a more complete understanding of the two different component characteristics of the stern waves. We have developed a method to estimate the resistance due to the remaining following waves. Using this method, we have reached three main conclusions. The resistance increases considerably if the remaining following waves change to forward-oriented breaking waves. The resistance coefficient of the remaining following waves increases only slightly with an increase in model ship size. This stern wave resistance coefficient is strongly affected by the forward-oriented breaking waves, and therefore decreases with an increase in model ship size. Received: January 5, 2001 / Accepted: May 28, 2001