Tartan 4000, Owner'S Manual, Page: 33 / 80

T4000 OM
4.2 Spars
Based upon the relationships described above, the more spreaders and shrouds used
transversely, and the more intermediate forestays and running backstays used
longitudinally, the smaller the allowable mast section may be. This can be advantageous as
weight aloft and windage may be reduced in addition to minimizing the undesirable
aerodynamic effect of the mast on the mainsail. The smaller the mast section, the less
disturbed is the air flow across the main. However, a practical and functional balance of rig
complexity and aerodynamic efficiency has governed the design of the rig of the Tartan
4000. The spar section and carbon fiber laminate schedule have been engineered to
provide a strong, stiff and safe mast while minimizing weight aloft.
Tuning involves adjusting the tension in these shrouds and stays so that the mast will
remain straight in most sailing conditions with an appropriate amount of rake for
comfortable helm balance. Tuning is carried out in two phases -­‐ tuning at the dock and
tuning while under sail.
4.3 Tuning at the Dock
All turnbuckles are equipped with toggles at their base, which eliminates bending load on
the swage and turnbuckle threads. Toggles are fitted to both ends of the forestay. As the
boat tacks and the headsail loading varies from side to side, the forestay terminals are
subject to extreme fatigue loading.
Start tuning the spar by ensuring that the mast is in the center of the boat, perpendicular
to the designed transverse water line. Your boat may not sit level at the dock due to
distribution of gear, stores and tankage levels, so check the water line position both sides.
Then slacken the lower shrouds completely by undoing their turnbuckles. Take the main
halyard and lead the shackle end to a point on the rail or chainplate. Adjust the halyard
so that the shackles just touch the reference point on the rail or chainplate with a given
downward tension, and then cleat the halyard. Then take the halyard to the same
reference point on the other side of the deck. With the same amount of downward
tension, you will be able to just touch the shackle to the reference point if the mast is
plumb transversely. If not, let off one upper shroud turnbuckle and take up on the other in
order to bring the masthead closer to center line until the halyard shackle touches both
reference points under the same downward tension.
The particular part of the rail or deck you choose as your reference point is not important
as long as it is the same point on each side. Once the mast is centered transversely,
tighten both upper shroud turnbuckles uniformly, one full turn one side, then one full turn
on the other. Repeat until the turnbuckles become difficult to turn. Pin the turnbuckles.