Surgeon Knots
The Surgeon’s Knot, or Surgeon’s Join, is easy to tie and is useful to join two fishing lines of moderately unequal size, e.g., a tippet to a leader. It is actually tied as a Double Overhand Knot – which probably explains why it is sometimes known as the Double Surgeon’s Knot – redundant because “Surgeon’s Knot” implies the use of the two turns.