Technical brochures
Sparcraft-us recommendations
© Charleston-Spar


You have now completed as much as possible by "dock tuning" the mast. If it is out of column then go over the procedure again, starting from the caps. Now plan to tune the rigging on the water !
On your first sail trials take a crew with you than can sail the boat whilst you concentrate on adjustments. Choose flat water with no more than a force 3 wind. Sailing to windward check up the mast track for aligment which should be straight. Make adjustment to the leeward shroud which should be under very little load, than track the boat to adjust the other side.
With the sails up it is useful to mark the halyards in their sailing position with an indelible pen or twine.



for Safety & Performance

Systematically alter each shroud, working from the top set, keeping the number of turns the same from side to side. Adjustments should be carried out on the leeward side where pressure is slack or reduced. Check the reaction before proceeding. With increasing pressure on the sailplan (about 20% of heel) the leeward shrouds and intermediates should just begin to slacken.

The forestay can be finally adjusted for the correct amount of rake.



with aft facing spreaders

This type of configuration requires increased shroud tension to ensure that the rig does not go slack. It is important to keep these masts relatively straight as this will provide best performance. Too much bend will cause rigging to slacken with an associated reduction in performance. As before, adjust the leeward shroud whilst it is not under pressure.
CAUTION : If standing backstays are fitted they should be used to carefully trim the topmast to improve upper sail shape and reduce mast panting in waves. If it is overtightened the backstay could induce too much bend allowing the shrouds to go slack.



with in-line spreaders

The in-line fractional spreader configuration should be set up as for the masthead rig, the only difference being the addition of running backstay to tension the forestay. More mast bend can be expected and the sailmaker will cut the mainsail accordingly. The mast should always be set up with some fore/aft bend as these masts can invert, particulary in stronger winds.
More experienced crew handling is required to control both tacks and gybes. If the runners are not made up in time after a gybe there will be nothing to stop the whole rig falling over the bow. When tacking keep some tension on the mainsheet as this should hold the mast in position if runners are not secured.
CAUTION : The checkstays allow you to trim the exact amount of fore/aft mast bend around the middle section. Over tightening them relative to the running backstay could cause a mast inversion !



At the completion of every stage remember to fit and open split pins, to lock the rigging to the yatch. When you have completed tuning it is advisable to seal these pins with tape so that they cannot catch sails or fall out.