Broaching-to is a sudden and uncontrollable turn in following or stern quartering waves. The phenomenon is typically preceded by surf-riding. The ship is captured by a wave approaching from her stern, accelerates to the wave celerity and loses directional stability regardless of the steering effort. The violent turn resulting from the directional instability may result in a collision or lead to a large angle of heel, possibly even capsizing. Once the conditions for such a dangerous response of the vessel are met, the crew is typically helpless, lacking time for any effective reaction and even hardly identifying the exact nature of the phenomenon they are suffering from. As fast, small to mid-size ships are especially vulnerable to broaching, the potential loss of directional stability in waves is of particular concern for the rapidly increasing fleet of autonomous vessels. The goal of this scientific project is to expand the contemporary knowledge of ship maneuvering in waves and dynamic stability through a study of the dynamic phenomenon of broaching-to and its precursor surf-riding. The systematic experimental study will examine phenomena associated with the motion of a ship sailing in irregular following seas, starting with a bi-chromatic wave. The surf-riding phenomenon has been demonstrated in numerical simulation, but have not yet been examined experimentally. The exploration of the surf-riding phenomenon with an advanced experimental setup in a towing tank may leverage the further development of the theory. The bi-chromatic approach further can be expanded to tri-chromatic and further towards to fully irregular wave.