Trawler. Fishing-vessel with ground-sweeping net.
Trim. Term indicating the state of a ship with regard to ballast; position of a vessel in the water with respect to horizontal.
Turtle-back. Top of wheel-house, forecastle, etc., formed like a turtle's back.
Upper Works. Same as freeboard when a vessel is loaded.
Uptake. Part connecting smokebox to funnel. Sometimes includes the smokebox.
Ventilator. Usually made of sheet iron in tubular forms, and arranged to expel foul air and permit the passage of fresh air to any part of a ship.
Vessel. Craft requiring a licensed master. (Boats do not).
Water ballast. Sea water let into double bottom or ballast-tank.
Water-Line. (Light) Submerging line of vessel without cargo.
Water-Line. (Load) Submerging line of vessel with full cargo.