We discuss the need for ship hull monitoring and the roles such asystem may fill during the different stages of a ship's lifetime. We havefound that fibre optic sensors are well suited for this application andpresent the fibre Bragg grating technology that has been employed in thecomposite hull embedded sensor system project (CHESS). Signal processing isthe key to real-time structure monitoring, and we comment on the modularsignal processing system that is being developed at FFI. Finally we presentthe CHESS installation on a new Norwegian naval vessel and show some resultsobtained with this system in systematic sea-keeping tests. The CHESSmeasurements on the new Norwegian fast patrol boat have been instrumental inthe design verification of the vessel.