Perpustakaan Digital ITB

The operations in oil and gas often involve a shuttle tanker. This shuttle tanker must be kept relatively calm during the operation and offloading process with mooring lines because the process has several risks such as collision, mooring failure, or even hose rupture. Ocean waves with a period of 25 -250s are called infragravity (IG). These waves are also dangerous for the ship because the sway and surge motion will be significant for long period waves. This study aims to design a single point mooring system with Catenary Anchored Leg Mooring (CALM) buoy at Cilacap Strait and simulate the ship response in a free-floating condition and moored condition under infragravity. HAWASSI-AB can simulate waves with nonlinear interaction and generate a wave with infragravity. The spectrum from the wave simulation result later will be used as input for ship motion simulation. The motion response between simulation with infragravity and without infragravity is compared to see the effect on the vessel motion and mooring system. The result in a free-floating condition shows that the vessel surge motion has a spectral density difference up to 2x107 m2s. The results in moored condition with infragravity show that the mooring chain and hawser line can have a maximum tension difference up to 100 kN from the result without infragravity. The vessel surge spectral density difference varies corresponding to initial heading and maximum value up to 1000 m2s.