tune that rigging
John de Frayssinet (editor of Yachting Life)

Get your sailcraft moving really well! You can achieve an extra ‘sparkle without knowing all the finer details of tuning standing rigging. What’s more, unless you own at least two oil wells, it is unlikely that you will be able to call upon the services of sail-trim experts and spar makers.

Performance to windward can be most affected by bad tune. If the mast is not dead upright athwartships then the yacht will not sail equally well on either tack. Ensure that there is sufficient tension in the forestay to prevent the luff of the jib from sagging away to leeward. It is most important that the mast does not develop kinks when hard on the wind. Adjustment of the cap and inner shrouds will prevent this.

The rake of the mast is also important. If the mast is raked too far aft the centre of effort will also be brought aft, causing excessive weather helm. The mast rake should be set to ensure a small degree of weather helm when sailing under full canvas in about 15 knots of wind. A yacht tuned with a degree of lee helm is potentially dangerous, as the boat may bear away from the wind, causing an accidental gybe.

Three-quarter rigged boats are getting more common again. The main advantages in such a rig appear to be that a greater degree of adjustment can be given to setting the mainsail. In the modern yacht design which depends largely upon the drive of a large foresail. I question whether this additional adjustment of the main will compensate for the loss in foresail area.

masthead rig Mast should be stepped dead centre of boat. Adjust rigging with bare poles to ensure the mast is upright. Sail in about 1S knots wind hard to windward. Adjust weather main shroud to eliminate mast sagging to leeward. Adjust lower shrouds to take out mast sag. I Fore inner shrouds should have higher tension than aft inners. Main shrouds taut. Tack and repeat for other side. Forestay should be tightened to straighten mast when hard on - wind and foresail well sheeted. Forestay must not sag away with jib when hard on wind. Boat should show slight weather helm. This means the boat has tendency to point higher towards the wind. If weather helm too great, - tune stays to bring forward the mast. If lee helm (boat tends to bear away from wind) adjust stays to bring mast aft. Stay adjustments bring mast fore and aft. Adjustment of backstay only will increase tension. Tensioning of inner shrouds can bend centre of mast fore or aft. Mast should become straight when hard on the wind.

3/4 rig Three quarters of mast only is supported by forestay. This will allow bending of upper mast. Rake of mast held by running stays. Only weather runner must be under tension as boom fouls lee runner. Adjust main, and inner shrouds, fore and running stays as for masthead rig. Mark runner tensioners when correct tune found to ensure tune maintained after tacking. Upper diamonds support top of mast. Mast can be bent forward by increasing shroud tension. Bend occurs above forestay. This will increase tension on mainsail leech. If upper shrouds are not self balancing, ensure tensions bring mast straight. To bring centre of effort forward (e.g. for off wind) let off runners, ease tension on backstay and tension forestay.   in (7) Upper mast bent forward by upper shroud tension. in (8) Upper mast bent aft, easing mainsail leech. Maintain tension on forestay and runners. Tension backatay and loosen upper shrouds if necessary

names of components 1. Main shroud 2. Back stay 3. Forestay 4. inner forestay 5. Fore inner shroud 6. Aft inner shroud 7. Backstay tensioner. 8. Crosstrees 9. Upper diamonds 10. Running stay.