What is the standard tie off knot used during rib stitching?

The standard tie-off knot used during rib stitching is the modified seine knot, which is particularly effective because it provides a secure finish for the stitches. This knot is designed to hold well under tension, which is essential in applications like rib stitching where the integrity of the fabric is crucial for aerodynamic performance.

The modified seine knot is also versatile, as it is appropriate for all stitches with the exception of the starting stitch, which typically requires a different knot to ensure a firm anchor point. This design allows for a neat and functional finish, maintaining the strength necessary for the tension involved in rib stitching.

In contrast, other knots such as the square knot and bowline are not as suitable for rib stitching applications. The square knot, while useful in many situations, can slip if not properly secured, compromising the integrity of the stitching. The bowline knot, although strong and reliable, is generally used in different contexts where a fixed loop is necessary rather than in the direct tie-off needed for rib stitching. The half hitch knot, while easy to release, does not provide the necessary strength for rib stitching and can easily come undone under stress. Therefore, the modified seine knot is the best choice for ensuring durability and security in rib stitching.