Skibe er udsat for et komplekst vibration miljø, påvirket af havet, samt driftsforholdene. Især er det vanskeligt at anslå analytisk værdier for de hydrodynamiske påvirkninger. Eksperimentelle resultater er derfor vigtigtfor at kontrollere de analytiske modeller. I den foreliggende artikel præsenteres foreløbige resultater fra en fuld skala modal test af en Ro-Lo skib, under tre forskellige driftsbetingelser. Da modal test i fuld skala skibe i drift er sjældne, præsenteres forsøgs opstillingen sammen med foreløbige modal parametre udtrukket fra målingerne. Denne foreløbige undersøgelse fokuserer på driftsforhold påvirkning af de modal parametre og viser en betydelig variation af modal dæmpning af skibet i drift, med cirka 400%, 200% og 400% forskel i de første tre globale lodrette bøjning modes, ved forskellige operations hastigheder.

Sea vessels are exposed to a complex vibration environment, influenced by the sea as well as by operational conditions. Particularly, the hydrodynamic load effects are difficult to estimate analytically. Experimental results are therefore important to verify the analytical models. In the present paper preliminary results from a full-scale modal test of a Ro-Lo vessel carried out for three different operating conditions are presented. Since little full-scale modal testing seems to have been conducted on vessels in operation, the experimental setup together with preliminary modal parameters extracted from the measurements are presented. This preliminary study is focusing on investigating the data with respect to operational conditions and shows a significant variation of the modal damping of the vessel in operation, with approximately 400 %, 200 % and 400 % difference in the first three global vertical bending modes, respectively.