Treenails or Trunnels  Treenails were used as fasteners for
shipbuilding. They were often made of locust wood. They were
less expensive than bolts for fastening, and they made tight
connections. The treenail is like a large dowel, pounded into a
hole drilled through the pieces of wood to be fastened together,
and set by pounding wedges into both ends, so that the treenail
will not come out. Treenails were often called "trunnels."  This
image is from Basil Greenhill and Sam Manning, The Evolution of
the Wooden Ship, 1988, p. 145. Used by permission of the artist,
Sam Manning.  Manning, Sam