Buttock Lines. Curves derived from a series of longitudinal sections of the hull of a vessel by vertical planes parallel to keel and at uniform intervals from it. They thus indicate the transverse form at any given thwartship position.
Butt Sling.Length of rope with eye splice in one end and whipping on other end.
Butt Strap. Piece of metal covering a butted joint. Riveted to each of the butted plates to regain strength lost by the butting.
Butt Weld. The joining of two members by putting their edges closely in contact and welding along the seam.