What knot do you secure the end of the line prussic with?

The bowline knot is the correct choice for securing the end of a line prussic because it creates a fixed loop at the end of the rope. This loop allows for adjustments and maintains tension without slipping, which is essential in climbing, rescue operations, or applications where a secure, yet adjustable connection is necessary. The bowline knot is reliable as it does not jam under load and can be untied easily after being subjected to tension.

Other knots, such as the square knot, double bowline, and figure eight, may serve different purposes but do not provide the same flexibility and reliability that the bowline offers in this specific context. For example, the square knot is primarily used for joining two ropes of similar diameter but does not create a loop nor provides the security needed for a prussic. The double bowline also creates loops, but it is typically used in different situations. The figure eight, while strong and secure for creating a loop, is less ideal than the bowline for the specific adjustable feature required in a prussic.