The T-knot is a specialized fishing knot used primarily in bottom fishing to create a rigid branch line (dropper) that extends away from the main line. It prevents snoods (hook lines) from tangling around the main line in double-dropper rigs, especially for surf fishing, and functions as a strong connector to attach hooks or lures to a leader system.
The T-Knot (or Tuna Knot) is a popular, strong fishing knot for attaching leaders to hooks, but its main disadvantages include being time-consuming to tie, difficult to properly seat on thicker lines, and prone to failure if the tag end is too short or if used on braided line.
