What is surfing and broaching , what is the action required to prevent ?

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Surfing
When a ship is situated on the steep forefront of a high wave in following or quartering sea conditions, the ship can be accelerated to ride on the wave. This is known as surf-riding. In this situation the so-called broaching-to phenomenon may occur, which endangers the ship to capsizing as a result of a sudden change of the ship’s heading and unexpected large heeling.
Broaching
Broaching is an unintentional change in the horizontal-plane kinematics of a ship. Broadly, it may be described as the “loss of heading” by an actively steered ship, that is accompanied by an uncontrollable build-up of large deviation from the desired course. Broaching is more The third distinctively identified, commonly arising in waves which come from behind and propagate in a direction forming a small angle, say 10-30deg, with the longitudinal axis of the ship. Although the inception of broaching represents a problem of instability on the horizontal plane, capsize may be incurred at the post critical stage due to development of large heel as energy is transferred into the roll direction. Broaching could happen to small as well as to larger ships. It is notable however that the dynamics involved do not seem to fit always into a single pattern. Frequently, broaching is manifested as a sudden divergent yaw, which peaks within a single wave length. Control is lost when the middle of the ship lies somewhere on the down-slope and nearer to the trough. In other cases there is a gradual, oscillatory-type build-up of yaw as successive waves impinge on the ship from behind. In moderate sea states a ship is more likely to broach-to if it runs with a high speed and is slowly overtaken by the waves. Broaching may also occur at lower speeds if the waves are very steep.

Action :Course and speed to be changed to avoid surf riding and broaching

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• What is surfing and broaching , what is the action required to prevent ?