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post #8 of Old 12-20-2006
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Many things will prevent a boat from properly 'pointing up': rig tension, sail condition, sail SHAPE, rudder/helm balance, etc.

If the rigging isnt properly tuned/ttensioned, the forestay maybe too slack and will sag off to leeward with the result is that the boat will heel way over but not go 'anywhere' and you start to develop a LOT of 'weather helm' thus additionally 'putting on the brakes'.

All jibs/genoas are specially cut/curved on their luff so that the curve of the luff matches the *normal* sag of the forestay; most sailmakers 'assume' that the tension on the forestay is set up/tensioned to somewhere between 12-15% of the ultimate breaking strength of the wire. A rigging tension gage is needed to precisely get to those values ... but isnt needed unless you are racing, etc. .... You can use your *Mark-I eyeball* to get close to these 'sag' values with the following method: take your jib/genoa and lay it out on a CLEAN flat surface, make a 'double fold' (pleate) in the sail about 2ft back from and parallel to the luff (this will allow the sail to lay FLAT on the ground, etc.), remove any 'creases' etc. that inadvertantly form as you want the sail smooth and FLAT in the section 2ft aft the luff. Have an assistant hold the head connection firmly as you run a string from the head down to the tack connection .... observe (and remember) the 'curve' that the luff makes when its FLAT, then measure the point of 'greatest distance' between the string and the luff. Get some adhesive backed fabric (draft stripe material .... from a sail makers supply works best) and place a small strip at the *same* measurement BACK from the luff. This measurement and shape that you 'remember' will now allow you to get (SEE) the proper forestay tension, the amount of forestay 'sag' to MATCH the curve in the luff of the sail .... as a 'basic setting' for *12-15kts*. of apparent wind. You then adjust the backstay tension to change the tension in the forestay (while underway) to get the 'basic setting' (curve) that matches the sail (for 12-15kts.).

To point even higher (but slightly 'slower') you can increase the backstay tension so that the forestay 'sag' becomes even less.
Also remember that when beating, etc. the more you 'load' a sail by straining the sheet on a winch the more additional forestay sag will occur .... needing either MORE backstay tension or LESS sheet tension to keep that luff curve 'reasonable'. That little 'strip' that you put behind the luff will help you visualize how much or how little luff sag there is. The sail will be at its maximum/optimal luff shape when that 'curve' matches what the sailmaker originally put in there.

Other: to help point higher (or lower with speed) you should also consider to apply hard halyard tension which will change of the 'shape' of the sail so that the point of where the draft is the greatest will be more-forward in the sail. More halyard tension in higher wind ranges and less tension in lower winds.

Obviously, there are many other such 'adjustments' for proper "sail shaping" but from what you describe, the above may radically change the way your boat 'points'. There are many books and 'articles' on sail-trim and shaping. Probably the 'easiest' is a guide written by Don Guillette (forget the name of the book but his name will allow you to do a 'websearch'), probably the most definitive and 'technical' (also 'free') is an accumulation of magazine articles by the the famous aerodynamicist Arvel Gentry ( .... go to that website, then go to 'magazine articles' then download:
Checking Trim on the Wind, November 1973
Achieving Proper Balance, December 1973
Sailing to Windward, January 1974
Are You at Optimum Trim?, March 1974
... these are 'sequential' from one large single article .... that set the sailing world 'on its ear' in the early 1970s. He's the one who 'debunked' the 'slot-effect' and other incorrect and still popular 'mysticisms' of how sails really work, etc. If they seem too technical, just read them several times over and over ... until you say "holy ****, this is incredible".

Hope this helps. ;-)
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