Floating breakwaters; a theoretical study and preliminary design of a dynamic wave attenuating system

Floating breakwaters; a theoretical study and preliminary design of a dynamic wave attenuating system

Van Tol, P.T.G.

Vrijling, J.K. (mentor)
Molenaar, W.F. (mentor)
Naaijen, P. (mentor)

Civil Engineering and Geosciences

Hydraulic Engineering

2008-04-25

Humans have been using ships to transport goods and people around the globe for hundreds and thousands of years. In all cases harbours have been critical for the exchange of goods and have played a significant role in the development of countries. Initially, harbours were located in sheltered natural bays; later breakwaters were used to provide shelter. An interesting next step would be the development of floating harbours at strategic locations. This would eliminate the need for capital dredging and can reduce the number of required harbour calls. A floating breakwater is an essential element in the design of a floating harbour to provide safe shelter for large scale floating structures. The missing link in designing an effective floating breakwater is a design-tool to make quick preliminary designs which can be developed further. A 2-dimensional linear spring model, the ReFBreak2D-model, has been developed to assess the performance of various floating breakwater designs. The hydrodynamic behaviour, as calculated by the model, has been validated with DELFRAC, a three dimensional potential model to determine reliability of the calculations. The results of the ReFBreak2D-model correspond well to the output of the DELFRAC simulation. The most important outcomes from the ReFBReak2D-model are: - The performance of the floating breakwater is primarily determined by the beam/draught ratio (Yw/T1-ratio) and the location of the centre of gravity (COG). - A rectangular floating breakwater with an Yw/T1-ratio of 5.0 and a high COG is the most optimal design. - A system of two floating breakwaters fulfils the requirements. These outcomes have been used to develop a preliminary design of the largest element. The length of the element is 500 metres, the beam is 100 metres and draught is 20 metres. This leads to a displacement of 1,000,000 tonnes, of which 270,000 tonnes are ballast. The element is moored using a turret mooring system; this makes it possible to weathervane during storm conditions.

http://resolver.tudelft.nl/uuid:dde70882-22bc-45de-a12b-860bbc2bac85

TU Delft, Civil Engineering and Geosciences, Hydraulic Engineering

Student theses

master thesis

(c) 2008 P.T.G. van Tol