Wave Effects on Ships Moored at Figueira Da Foz Harbour

Abstract

The Figueira da Foz harbour is located at the mouth of the Mondego River in the West coast of Portugal. Two shore-connected breakwaters that, due to their layout, have a quite poor performance shelter it. In fact, some of the incident waves cause large movements in the ships moored at the general cargo quay. The breakage of mooring lines is a quite common accident there. This paper presents the methodology employed and summarizes the results obtained in both the wave penetration study when the harbour basin is dredged up to -7.00 m C.D. and the study of the wave effects on the behaviour of a ship moored at the general cargo quay. INTRODUCTION The Figneira da Foz harbour, Fig. 1, is located at the mouth of the Mondego River on the West coast of Portugal. It is protected by two shore-connected breakwaters: the so-called North (776 m long, crest level +6.00 m C.D.) and South (980 m long, crest level +6.00 m C.D.) breakwaters. The harbour entrance is 250 m wide and faces west. The port facilities are distributed on both margins of the Mondego River and include a general cargo quay, a marina and a fishing dock. Nowadays, the seabed depth at the outer-harbour and at the harbour channel is around -5.00 m C.D.. Close to North breakwater head the seabed depth reaches -14.00 m C.D.. The wave regime at the harbour entrance, Fortes et al. (2000), is characterized by wave directions ranging from SW (225 ~ to W-60~ (330~ the most frequent wave directions being those of the sector W to NW. The values of the zero crossing period, Tz, range from 6 to 14 s. The significant wave heights vary between 0.16 and 8.4 m, the most common values being in the interval 0.5 to 3.0 m. Records from the Port Authority Research Officer, jasantos@tnec.pt, 2 Research Officer, gneves@lnec.pt, 3 Research Assistant, jfortes@lnec.pt Hydraulics Department, L.N.E.C., 1700-066 Lisboa, Portugal