Seawind 1000XL2 Owner's Manual page 7

Owners Handbook 7
The outer diamond wires control the mast pre-bend aft and ensure that it cannot
bend sideways. The mast is initially set up with approximately 235mm of pre-bend
(ie the mast has a gentle bend along its length so that at mid-length it has an aft
bend of approximately 235mm from an imaginary straight line between each end of
the mast). This is achieved through tensioning the outer diamond wires with the
forward spreader wires completely loose. With the correct pre-bend achieved,
tighten the inner diamond wires until they are firm (these do not need to be as tight
as the outers as they are not used to induce pre-bend. Now adjust the lowers until
the mast bend has been reduced to approximately 115mm. At this stage, the
diamond wires should be very tight. ("guitar string" tight).
Having the mast properly set up you now need to look at the stay tension. The
forestay length has been determined to allow the mast to have an aft rake of
approx. 400mm (15 inches). This means that the mast-head will be further aft than
the mast foot by 400mm. Next tighten the side stays on both sides. These should
feel tight but without over-tensioning. Achieve this by firstly hand tightening and
then, using a wrench, further tighten four full turns or until they feel firm. Do not over
tighten, as all you will do is bend the actual boat. A good guide as to whether the
correct tension has been achieved, is to try to move the stay with your hand at
approximately shoulder height from the deck. You should be able to move the stay
through a circle with a 75mm (3") diameter (but no more).
Now go sailing. The correct rig tension for the Seawind 1000XL2 can best be tested
with the boat at sea. In a reasonable sail to windward (say, in 15 knots or more),
the lee stay will slacken. This is normal & acceptable. However, it should only go
slack & not "flop" around. If it does "flop" around – tighten it to take out the slack
(count the number of turns). Tack and take up the same amount on the opposite
side so as to balance the tension on each side.
Once you have completed all the above steps, the rig should be well set up &
should not need adjusting again. However, one last check is worthwhile. When
sailing hard to windward (say in 20 knots), go to the base of the mast & look up its
length. It should be perfectly straight in its side-ways plane all the way up until the
jib halyard exit. Above this point, the mast is unsupported & it is normal that this top
part will fall away to leeward. In a fore & aft plane, the mast will be bending slightly
aft but not pumping.