第 四 題

"Under keel clearance (UKC)" refers to the vertical distance between the lowest point of the ship's keel and the seabed. Key features include: (1) Safety function: It serves as a vital safety margin to prevent the vessel from grounding or striking underwater obstacles.

"Metacentric height (GM)" refers to the vertical distance between the center of gravity (G) and the metacenter (M) of a vessel. Its key characteristics include: (1) serving as a fundamental measure of a ship's initial static stability; (2) a large GM results in a "stiff" ship with a short, rapid roll period; (3) a small GM results in a "tender" ship with a long, slow roll period. In practical maritime application, maintaining an adequate positive GM is strictly required by IMO stability criteria to prevent capsizing and ensure navigational safety. （中文輔助說明：「定傾中心高度」指船舶重心與定傾中心之間的垂直距離。特徵包含：(1)作為衡量船舶初始穩度的基準；(2) GM過大會使船體搖晃過於「猛悍」；(3) GM過小會使船體搖晃過於「柔弱」。實務應用上，必須維持適當的正GM值，以符合IMO穩度標準並防止船舶翻覆。）

"Able seaman" (AB) refers to an experienced and certificated deck rating who has met the specific qualification requirements under the STCW Convention. The core characteristics include: (1) Serving in the deck department as an unlicensed personnel.

"Displacement" refers to the total weight of the volume of water displaced by a floating vessel. Key characteristics include: (1) According to Archimedes' principle, it is exactly equal to the actual total weight of the ship and everything on board, including the hull, machinery, cargo, bunkers, fresh water, stores, and crew.

"General emergency alarm" refers to a specific acoustic signal comprising seven or more short blasts followed by one long blast on the ship's whistle or siren, and additionally sounded on an electrically operated internal alarm system. Key characteristics include: (1) Acoustic pattern: Consists of seven or more short blasts followed by one long blast.