A thruster is a small propulsive device used by spacecraft and watercraft for station keeping, altitude control, or long duration low thrust acceleration. It consist of a propeller installed in a tube and are located cross-wise to the longitudinal axis of the ship. They are always installed near the bow and sometimes also at the stern. When the thrusters are used in the berthing operation, they will generate a water current that will hit the quay front or the slope below an open berth structure directly and be diverted to all sides from there. If the water current hits a vertical berth front, e.g. a steel sheet pile wall, a part of the water current will hit the sea bottom and can cause erosion in the immediate vicinity of the berth wall.

Thymol is a monoterpene phenol. It is a derevative of cymene, C10H13OH, isomeric with carvacrol, found in oil of thyme, and extracted as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties. It is also called hydroxy cymene. It has been found to be useful in controlling varroa mites in bee colonies. It is also used as a preservative in halothane, an anaesthetic. It is described as large, colorless, translucent crystals of the hexagonal system that have an aromatic, thyme-like odor, and a pungent, aromatic taste. Thymol is used as an antiseptic, local anesthetic, cooling agent, and as a preservative. It acts as a local irritant and anesthetic to the skin and mucous membrane. It is found in liniments, lip balms, toothpaste, and mouthwash.  It is not compatible with strong oxidizing agents, organic materials, or strong bases. It is harmful if swallowed, inhaled or absorbed through the skin.  It is an eye, skin, and respiratory irritant.