This diagram shows how the frames or ribs are built for a Maine schooner. Because one cannot find a big enough tree that has exactly the right shape for the entire length of the frame, it is built in many pieces, called timbers and futtocks. The frame is double thickness, so that there is overlapping wood at the end of each futtock. The frames are built on a platform, then raised on the keel.
This image is from Basil Greenhill and Sam Manning, The Evolution of the Wooden Ship, 1988, p. 107. Used by permission of the artist, Sam Manning.