This is another skill in boat building where experience plays a role in applying it. Despite the work going in to ensuring that the frames are accurate prior to this stage in the build, the process of fairing frames is still vital. How each frame relates to its neighbour has a huge influence on the way a plank runs around them, affecting the aesthetics of the hull. Also contact between frame and plank is important structurally.
The person carrying out this process must remember they are not only fairing along the vessel but also up each frame. It is really adjusting the bevel angle of each frame to enable the plank to sit on the frame and correcting any unfairness which has been built into the vessel during the early stages of the build.
The process is demonstrated in the accompanying video clips with a step-by-step guide. The process was captured on film by observing the garboard plank being fitted on the Grayhound. There is no discussion with the shipwright during the process, but all the key tasks are recorded in the subtitles.
It is important to develop the subtlety of the process, which is very influenced by the properties of the fair plank. Too stiff, too much may be removed, too flexible, too much left on. Fair with the bigger picture in your mind.