The Prusik

This is a knot I use a lot, which rarely appears in sailing manuals, presumably because it

was invented by a mountaineer for use in crevasse rescue. The Prusik knot is very easy to tie and has many uses two of which are illustrated below.

It enables you to attach a strop of light rope onto another heavier rope without getting at the free end of either. When the strop is under load the knot locks onto the main rope and will not slide in either direction; i.e. it behaves like a two-way rolling hitch. When the load is released the knot can be easily loosened and slid at will either way along the main rope.