Design Methods for Marina Facilities in Cold Regions and the Effective Use of the Marina
Takashi Terashima Pacific Consultants Co., Ltd.
Takahiko Sasajima Hokkaido Development Bureau
Tetsuya Hayakawa Hokkaido Development Bureau
Minoru Yoshida Nishimura-gumi Co., Ltd.
Shoji Hamaoka Okhotsk Sea Ice Science Research Co., Ltd.
Hiroshi Saeki Hokkaido University
Abstract
We present design methods for floating structures in cold regions. Recently marine recreation, such as yachting and motorboating, has become popular in Japan. In Hokkaido, the northernmost island in Japan , four public marinas have been constructed on the coasts of the Pacific Ocean and the Sea of Japan. This has led to an increase in the popularity of marine activities. However, no marina has been constructed on the coast of the Sea of Okhotsk, where sea ice causes many problems to marina structures.
On the other hand, many marinas have been constructed on the coast of Northern Europe under the same climatic conditions as the Sea of Okhotsk, and these marinas are used actively, except during the periods when the harbors are covered with sea ice.
When we design marina facilities in cold regions, we need to consider the influence of ice on the floating structures. In this paper, we propose design methods for marina facilities from an experimental study considering the influence of ice on the floating structures.
Recently, marine recreation with pleasure boats, such as yachting and motorboating, has become popular in Japan. These marine recreation types are in great demand also in Hokkaido, including the coastal areas of the Sea of Okhotsk, where ports and harbors are covered with sea ice and are affected by drift ice in winter. To design the semarinas and facilities for pleasure boats in sea are as frozen in winter, careful consideration of the influence of ice is necessary.
In this study, we made field experiments on the influence of ice upon floating structures in Mombetsu Port to examine how to design floating structures inmarinas and other facilities.
2. Method of the Field Experiments
2. 1 Site
These field experiments were made in the No. 4 basin for small craft in Mombetsu Port, one of the major ports, on the coast of the Sea of Okhotsk in Hokkaido. The port is covered with sea ice usually from late January to mid March. The No. 4 basin for small craft is the closest basin to the port entrance; its water depth is 4 m, and the total lengths of the inclined quay and the slip way are 200m and 50 m, respectively.
2. 2 Experimental Method
We assumed that floating bodies behave differently according to the freezing condition in the port. The following two items were observed in the experiments.
?Freezing condition
The freezing conditions of the No. 4 basin for small craft and around the floating structures were recorded.
?Behavior of the floating bodies
The vertical displacement of the floating bodies caused by the changing tide level was measured by leveling four corners of the floating structure. The horizontal displacement of the floating bodies, caused by wind, currents and sea waves, was obtained by measuring the angle at two points on the floating structure.
2. 3 Floating bodies and their mooring method use din the experiments
Usually, ice floes undergo flexural failure around a quay wall, causing a strong influence upon the floating bodies. However, the influence of ice on the floating bodies varies depending on whether the floating bodies and the ice floe are in contact with each other at right angles or at an angle of tilt. Also, whether the ad freezing of floating bodies to ice floes occurs depends partly on the color of
