When a ship pulls up to a dock to be moored the ships crew throws one of these rope balls out to the dock's crew. It is attached to a light rope line. The dock crew attaches a heavier rope leader line right behind the monkey fist and the ships crew pulls the line back. The ships crew then removes the monkey fist line and attaches the docks line to their heavy mooring ropes or cables.

The monkey fists have something heavy inside of the rope so that it can be thrown a good distance. If you ever have a chance to watch a high ship being pulled into a dock, take the time to watch. Usually there is some friendly banter between the crews during the initial throwing and catching of the monkey fist. The whole process is interesting and fun to observe.