Effectiveness of Floating Breakwaters
Background
Floating breakwaters are classified as a special type of breakwater and are applied at locations where conventional breakwaters are not suitable to apply [Verhagen et al., 2009]. In general it is attractive to apply a floating breakwater in deep waters where short waves occur in order to protect small ports and marinas against waves. Situations like this are for example deep lakes where only wind waves are present. One of the main advantages of applying a floating breakwater in a port is that the layout of the port can easily be changed and the floating structure can also be used as walkway. From an economical point of view it is often cheaper to apply a floating breakwater in deep waters instead of a conventional breakwater.
Research motive
The main objective of a floating breakwater is to protect an area against undesirable wave heights, a port for instance. One of the most important boundary conditions of a port design is the allowable downtime. This is the time period in which the port cannot operate. The downtime is often based on a certain wave height, which is considered to be responsible for unwanted ship movements. This implies that the penetration of waves around the floating breakwater into the port determines the downtime of a port. Therefore, wave penetration around a floating breakwater is assumed to be the most important parameter determining its effectiveness. Because of this it is necessary to determine the wave transmission of a floating breakwater as accurate as possible.
Over the last couple of years floating breakwaters are applied more often in small ports and marinas, particularly in areas with large water depths. The effectiveness of a floating breakwater strongly depends on the incident wave period and the dimensions of the structure, which makes it a complex problem. From previous engineering- and research projects on floating breakwaters, it turned out that the effectiveness of floating breakwaters is often overestimated. The main reason for this are the simplified design formulas used to calculate the wave transmission. These design formulas do not take all the processes of wave attenuation into account of a floating structure. This created the need for a solution to predict the effectiveness of floating breakwaters more accurately during the design stage.
Thesis aim
The aim of this thesis is:
- Identifying the steps which can be taken during the design process, in order to predict the effectiveness of floating breakwaters more accurately
- Investigating the wave penetration of realistic conditions (wave climate and oblique incident waves) for a pontoon type floating breakwater and the possibility how to include these effects into a formula determining wave transmission.
Info:
