Hull stress monitoring system (HSMS)

A hull stress monitoring system (HSMS) is a permanent array of strain gauges and accelerometers on deck and at high-stress hull locations that reads hull-girder stress, motions, and slamming in real time and warns the bridge when measured stress approaches the structural limit. Long strain gauges at deck amidships capture the wave and still-water bending stress; bow accelerometers flag slamming and whipping. Class notations require or credit HSMS on large bulk carriers and some tankers, and the system is calibrated and verified during sea trials. The output lets the master slow or alter course to cut wave loads. It records the fatigue and extreme-load history the structure actually accumulates.