- Ensure mast is upright in the boat, checking laterally with a spirit level, and longitudinally with a plumb line from the main halyard; also check that the mast step is on the centreline of the boat by running a line from the jib tack fitting to the centreline of the transom; adjust as necessary.
- Check that spreaders are deflecting the mast equally, and not twisting or pushing it out of column.
- Check that lowers do not pull the mast out of plumb as they are tensioned up. Adjust them if they do.
- Check that there is full travel on the lowers for the full range of rake available.
- Set the datum rake to 150mm by measuring from the lower measurement band to the plumb line, with the shrouds just snugged up to take all the slack out of the system. Mark the position of the tail of the halyard, or some similar conspicuous detail, on the back of the mast. Call it 'O'.
- Snug up the lowers until they just begin to deflect the mast. Find an easily identifiable place to record this position - on most deck stepped masts there is a convenient post just in front of the king post onto which tape can be put to mark onto, either way it must be clearly visible to whoever in the boat is responsible for rig adjustment while racing - and mark it '0'.
- Increase the rake by 50mm, re-tension the shrouds, mark this point on the mast and call it '1'.
- Snug up the lowers until they just begin to deflect the mast, and mark this point '1'.
- Increase the rake by 50mm, re-tension the shrouds, mark this point on the mast and call it '2'.
- Snug up the lowers until they just begin to deflect the mast, and mark this point '2'.
- Continue until full rake is achieved.
- Race the boat in a variety of conditions to determine which positions are optimum, always remembering that although carefully arrived at, these calibration marks are arbitrary! It may very well be that half way between your rake marks is where the sweet point for the boat lies, and that rake two combined, for example with lowers one, gives the best pointing in force three. The permutations are endless and will vary according to the fullness or flatness of the main, the bendiness or stiffness of the mast, and the roughness of water on which you happen to be racing on any particular day. Racing against other boats, two boat tuning if you can arrange it, is the only way to arrive at optimum settings. Clearly, careful recording of your findings each race are essential to improving performance, and if after a couple of months you feel that you have a good handle on what works best where, redo your marks to reflect your findings.
- Delegate rig operation to your crew, get your head out of the boat, and make sure you are pointing it in the right direction!
See also:
Setting up the mast - Graham Williamson
Rig Tuning - Mike Calvert
How To Tune
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