TACK, a rope used to confine the foremost lower corners of the courses and stay-fails in a fixed position, when the wind crosses the ship's course obliquely. The same name is also given to the rope employed to pull out the lower corner of a studding-fail or driver to the extremity of its boom.
The main-fail and fore-fail of a ship are furnished with a tack on each side, which is formed of a thick rope tapering to the end, and having a knot wrought upon the largest end, by which it is firmly retained in the clue of the fail. By this means one tack is always fastened to windward, at the same time that the sheet extends the fail to the leeward.