The transom is the transverse, vertical section that makes up the rear, or stern of a boat directly opposite the bow. Transoms are flat or curved and are as high as the hull or low as the waterline. A vessel's name is commonly displayed on its transom.
A transom can curve toward the bow from the water or away from it. When the lower tip of a boat's transom is above the waterline, it's called a transom stern. A low transom allows a ship to take on too much water and is a common reason for boats to sink. An outboard motor is mounted to a smaller boat's transom, either with clamps or with bolts.