This is often used for creating planks on traditionally built boats that have complex shapes.
This is then temporarily attached to the boat in the place of the plank required.
The shape of the plank required can then be traced onto the spiling batten using a compass, or a dummy stick.
[3] When spiling a complex shape curved in more than one direction, it is important to keep the dummy stick in the same orientation, and not allow it to follow the curve, otherwise a distortion of the shape will result.
This process enables more complex shapes to be built in wood than in sheet metalworking for example, would require stretching by hammer/mallet and sandbag or the use of an English Wheel.