Ocean Engineering 29 (2002) 1781–1804 www.elsevier.com/locate/oceaneng Surface-penetrating flexible membrane wave barriers of finite draft W.K. Lee, Edmond Y.M. Lo * Nanyang Technological University, School of Civil and Structural Engineering, Nanyang Avenue, Singapore 639798, Singapore Received 13 June 2001; accepted 7 November 2001 Abstract The performance of surface-penetrating flexible membrane wave barriers of finite draft is studied. The interactions of a single membrane and dual membrane systems are examined with various system parameters. The analytical solutions are derived using eigenfunction expansions assuming linear wave theory and small membrane response. Wave transmission is determined for various combinations of membrane draft, protrusion above the water surface, membrane tension and membrane spacing. The numerical solutions are compared with data obtained from experiments conducted. Comparisons of transmission coefficient and energy loss show good agreement with suitably chosen parameters of viscous losses.  2002 Elsevier Science Ltd. All rights reserved. Keywords: Membrane wave barriers; Membrane arrays; Wave scattering; Flexible membrane 1. Introduction Floating and/or flexible wave barriers have generated interest amongst researchers with some of its added advantages. They can be moored despite unfavorable seabed soil conditions and are usually positioned near the water surface where the wave energy is most pronounced. They allow for free passage of seawater, fish and sedi- ment transport beneath, thus being friendlier to the environment. They can also be more economical compared to fixed-type breakwater especially when the water depth * Corresponding author. Fax: +65-792-1650. E-mail address: cymlo@ntu.edu.sg (E.Y.M. Lo). 0029-8018/02/$ - see front matter  2002 Elsevier Science Ltd. All rights reserved. PII:S0029-8018(02)00007-0