Tuning - GRAMPIAN 34 Owner's Manual

TUNING YOUR BOAT

Tuning

Mast tuning is a very simple exercise, but it can when done result in better bo
speed. This can be more fun when cruising and better r
Tuning the Mast- Side to Side
1) Center the mast on the boat. Measure the distance from the mas
to gunwhales. The distance from the mast to both the port and
starboard sides must be equal.0n your Grampian these
measurements should b
installed sometime after the boat originally left the factory. Minor
adjustments can be made by lacing chocks in the mast ste
channel.
2) Tighten the upper shrouds until they are supporting the mast and
it appears to be vertical. Using the main halyard and a tap
mea sure, check the distance from the chain plates to the top of
the mast. The distance should be equal on both sides. If not,
adjust the upper shrouds until they are equal. You may have
take up on one shroud or adjust both depending upon how far o
the two measurements are from matching each other.
3) Now tighten the lowers to eliminate center bend. The final step is
done under sail, preferably in a medium range wind.
4) Sail upwind on starboard ta
degrees tighten the leeward upper shroud until all slack is
eliminated. Switch to the port tack and tighten the other shr
Important: Ensure that you tighten each upper shroud by th
same amount. Only in this way will the mast remain square to
boat.
If your boat has two sets of lowers, the forward lowers which encourage fore-aft
b end should be tighter than the aft lowers which reduce fore-aft bend. Two sets
of lowers require more work to be properly adjusted, but they can tuned and can
provide greater flexibility and control over sail shape.
Tuning the Mast- Rake
The fore and aft tilt of the mast is called r
th e forestay and the backstay. Rake affects the center of effort and can make the
b oat faster depending upon wind conditions. In heavy air it is advantageous to
in crease the take in your mast and increase forestay tension. In light air you will
w ant to do the opposite. Consequently, a permanent rake setting which is
a ppropriate for a Grampian is a matter of compromise. It is also a matter of trial
a nd error.
T uning the Mast - Bend
M ast bend is the part of tuning which is constantly changing due to wind and sea
c onditions. Mast bend affects depth and twist of the main sail.
23.
esults when racing.
e equal unless a new mast step has been
ck. When you are heeled about twenty
ake. Rake is affected by the length of
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