NavList:

A bit more on what I was rattling on about w.r.t. halyard tightening.  Take a 60 ft mast with a halyard down it cleated with 3/4 turn and someone trailing at its bottom and over a pulley at the top weighted down by a very large heavy sail.  At the centre of the mast pull out one foot of halyard.  The angle between the halyard and the mast is two degrees (1 in 60 rule), so the length of halyard is now 2x30/cos2degrees ft = 60.04 ft.  By pulling out 1ft at the centre the person trailing can pull in 0.04 ft of halyard, and you’ve raised the sail 0.04 foot, a velocity ratio and mechanical advantage of 25:1.  It works with mooring lines too and leads to fewer sailing led divorces.  DaveP