(From Fun With Knots Book, p. 38)
This lashing is used to "spring" two spars together. The lashing is started with a timber hitch around both spars. The timber hitch is tightened so as to draw the two spars together. Three or four turns are then taken around one fork, and three or four turns around the other fork. Two frapping turns are taken about the lashing at the point where the spars cross, and the lashing is finished off with a clove hitch around the most convenient spar.