Trial Trip. Short voyage of a newly-built, or repaired, vessel to test engines, steering, and other machinery, and to ascertain ship's capabilities and deficiencies.
Triangle Knot. Made in bight of rope so that two firm loops are formed. Not used in practical work, but is of interest as being a ceremonial knot of Brahmins.
Triangulation. Method used in surveys. Distance between two stations being known accurately, the distance of another station can be computed trigonometrically from the angles between it and each of the other stations.