Rig Tension
(# of turns past hand-tight)
CAPS ..................18.0 turns
D1s ...................... 4.0 turns
D2s ......................Hand tight
This is a good baseline tension which
optimizes speed and shape for a
Headstay length — Headstay should
be 48’11” from centerline of the pin
passing through the upper mast tang
to the centerline pin of the tang at
the bottom of the headstay (see pho-
tos at right). The headstay should be
adjusted according to increases in
wind speed. The range setting from
light air to heavy air is 2”.
Centering the spar
—Center the
spar with the main halyard to the cap
shrouds. The mast should be placed
14’8” from the stem sheer line to the
front face of the mast.
Mast butt location
— Move the
mast collar max-aft. The mast butt
should be max-forward to produce
1.5” of pre-bend. This opens the slot
between the main and genoa making
it easier to generate more tension on
the headstay with the limited amount
of backstay adjustment permitted by
the class. Be sure to lubricate the step
and bolts.
Tensioning the Shrouds
— Install
the cap shroud on the aft outside hole,
the lower diagonal shroud (D1) on the
forward hole, and the diagonal shroud
(D2) on the inside hole (see photo) .
Since we want to encourage the mast
to bend forward down low, we put the
D1 on the forward hole. We put the
cap shroud on the aft hole to help
keep it as tight as possible. Once hand
tightened, add the following number
of turns to the verticals and diagonals.
For tuning purposes, tie the shrouds
together before you go sailing, which
allows easy adjustment. Once final
adjustments are made, be sure to pin
the shrouds and tape generously to
avoid chafe.
J/35
Tuning Guide
5
SETTING UP THE RIG
headstay length of 48’11” in a wind
strength of 0-6 knots true. In 7-12,
shorten the headstay to 48’10”. For
wind speeds over 12 true, shorten the
headstay to 48’9.5”.
Mastbend
— Five factors control
bend; Backstay tension, runner load,
prebend or headstay length, mast butt
position and finally partner hole
position. What happens when we
change any of the five factors? For
example, if we:
a)
Make the headstay 1” longer
- we are adding prebend which
flattens the main in the lower-half
and softens the headstay.
b)
Pull the runner/checkstay
-
total bend is reduced, the headstay is
tightened, and the mainsail gets
deeper.
c)
Move the butt aft
- we add
prebend.
d)
Bend the mast with backstay
tension
- bending increases
headstay tension. This flattens both
sails and moves the draft aft.
CAP
D1
D2
