The motion response of floating structures is of significant concern in marine engineering. Floating structures can be disturbed by waves, winds, and currents that create undesirable motions of the vessel, therefore causing challenges to its operation. For a floating structure, mooring lines are provided in order to maintain its position; these should also produce a restoring force when the vessel is displaced. Therefore, it is important to investigate the tension of mooring lines and the motion responses of a twin barge when moored to guarantee the safety of the barge during its operation. It is essential to precisely identify the characteristics of the motion responses of a moored barge under different loading conditions. In this study, the motion responses of a moored twin barge were measured in regular waves of seven different wave directions. The experiment was performed with regular waves with different wavelengths and wave directions in order to estimate the twin-barge motions and the tension of the mooring line. In addition, the motion components of roll, pitch, and heave are completely free. In contrast, the surge, sway, and yaw components are fixed. In the succeeding step, a time-domain analysis is carried out in order to obtain the responses of the structure when moored. As a result, the Response Amplitude Operator (RAO) motion value was estimated for different wave directions. The results of the experiment show that the motion components of the twin barge have a significant effect on the tension of the mooring lines.

Abstract
 1. Introduction
 2. Test facilities and test conditions
  2.1 Wave basin
  2.2 Measuring device
  2.3 Twin barge model
  2.4 Test conditions
 3. Model test
  3.1 Wave maker calibration
  3.2 Measuring device calibration
  3.3 Ballasting and inclining test
  3.4 Inertia test
  3.5Installation of model test
  3.6 Data analysis
 4. Result
  4.1 Motion response results of model test inmoored condition
  4.2 Tension of the barge model in mooredcondition
  4.3 Vertical acceleration in moored condition
 5. Conclusion
 References

• Van Minh Nguyen(Graduate school of Changwon National University)
• Myung-Jun Jeon(Graduate school of Changwon National University)
• Hyeon-Kyu Yoon(Associate Professor of Changwon National University) Corresponding author