This research fills the gap in understanding fluid–structure interaction (FSI) from wave diffraction forces on CALM buoys and cylindrical structures, based on the hydrodynamics with connections. Recently, there is an increased application of (un)loading marine hoses for Catenary Anchor Leg Moorings (CALM) buoy systems in the offshore industry due to the need for more flexible marine structures that are cost-saving, easier to install, and service. However, different operational issues challenge these hoses, like during hose disconnection. Also, the fluid behaviour was investigated based on the analytical and numerical models. The numerical modelling involves the boundary element method (BEM) and Orcaflex line theory. Hydrodynamic analysis is conducted on the disconnection-induced load response of marine bonded hoses during normal operation and accidental operation under irregular waves. A comparative study on hose performance during normal operation and accidental operation is also presented. Results of statistical analysis on CALM buoy system shows good motion characteristics.