The present invention relates to an instrumentation assembly intended for an offshore riser (2) operated from a floater (1). It comprises a central processing unit (PC) connected by conducting cables (27) to: a plurality of modules (21 25) fastened to various points of the riser length, the modules comprising measuring means allowing dynamic location of said points in space, another locating module (26) fastened to the lower end (LMRP) of said riser, a series of detectors (W, C, M/W) for measuring the environment: wind, wave, current, an assembly for measuring the position (DGPS, P) of the floater. The measurements are synchronized with one another, managed and recorded by means of the central processing unit.