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In the spring of 2003, the Club 420 Class sails were
redesigned to provide a better competitive and useful
lifespan. Now that several events have been sailed using
the new sail design, it is clear that the new sails will
provide unprecedented durability as well as excellent
performance.
Because the new sails are shaped somewhat differently
than the old ones, there are several adjustments that
sailors should make when tuning their rigs. First,
lets have a look at what the major shape-affecting
changes are in the new sails.
Mainsail tack: The mainsail tack is now attached to the
mast by a slug which fits in the track, rather than
connected to the boom by a pin. This allows the tack to
float up, reducing the diagonal wrinkles you see in the
main when going downwind.
Mainsail shape: The mainsail is a bit flatter through
the bottom and middle sections of the sail, and the
leech is a little looser.
Jib clew: The jib clew is higher than on the old sails.
The area cut away in raising the clew is added back
elsewhere in the sail.
Jib shape: The jib is slightly flatter in the lower
part, with a significantly more open leech, especially
in the upper section of the sail.
Jib luff wire: The jib luff wire is slightly thicker
than on the old sails, but is made out of slightly
stretchier wire. The luff wires on the new sails are
overall a very small amount stretchier than the old luff
wires.
Rig Tuning Changes
Overall, the boat is rigged the same way as before. The
lines are all strung as before, the mainsheet bridle
remains unchanged, and all line lengths remain the same.
Mast butt position can be moved one to two holes aft
from the traditional pin max forward position.
Before, it was mandatory to have the mast butt placed
all the way forward in the step because the mast was set
up with so little rake. This will balance the helm as
much as possible. Most people sailing with the new sails
have noticed how nice it is not to have lee helm
anymore. The mast rake, mast butt position and helm
balance are all closely tied together.
With the old sails, the game was to set the mast without
any rake (rearward lean) at all. Because the jib lead
position on the C420 is fixed, the old jibs low clew
made it necessary to have the rig far forward in order
to get proper leech tension for good pointing. The old
jib was also quite finicky in that once you tensioned
the clew, it would very easily become overtensioned and
the leach would hook to windward. This is primarily due
to a design/construction detail which has been addressed
with the new sails.
Because the old sails set up with little rake, moving
the butt forward leaned the rig back as much as
could be done, easing the lee helm that usually crops up
when the rig is set up with very little rake. Because
the mast is now raked significantly more, moving the
butt backward one to two holes provides a rig with
properly balanced helm. If you feel a lot of weather
helm and, at the same time, feel a lack of pointing
(which is a very strange combination to have), you
should try moving your mast butt aft.
A benefit of having the mast butt further aft is that
you decrease the overlap between main and jib. While
this doesnt have a huge effect, it will allow you to
play the main a little more aggressively without having
the jib interfering with the main.
Rig tension has a profound effect on how your sails will
set. Simply, more rig tension will give you flatter
sails with more open leeches, while less rig tension
will give you fuller sails with tighter leeches. To
simplify things a bit, this just means that if you
needed more power you would ease the rig tension and if
you needed less power, you would increase rig tension.
Because the mast on a C420 is so stiff, the primary
effect of pulling on more rig tension is to tighten the
jib luff wire. This flattens the shape of the jib, and
to a smaller degree will pull the jib draft forward. It
will also loosen the leech of the jib. Pulling the draft
forward in a sail and flattening the sail both
contribute to loosening the leech. The magic of this, in
a C420, is that this allows you to trim the jib tighter
(with both the leeward and windward sheets) and thus
point higher. With this kind of setup you will have
greater speed and pointing in fully powered conditions,
but will lack power, and thus speed and pointing, in
lighter airs.
A Brief Warning About Rig Tension: Some sailors have
experimented with extreme rig tensions in their C420s.
This tuning guide recommends a maximum shroud tension of
350 pounds. Some crews may wish to go slightly firmer
than this. It is VERY POSSIBLE AND EVEN LIKELY that your
boat (hull or rigging) will suffer a breakdown if you
use more than 400 pounds of rig tension. The C420 was
not designed to sail under excessive rig tensions. Your
boats lifespan will be shortened if you regularly
sail with excessive rig tension. Before you go for that
extreme setting, ask yourself if you are willing to risk
a possible regatta ending breakdown by going for that
extra amount of rig tension.
Mast rake in a C420, as mentioned above, is a primary
driver of jib lead angle. To help with understanding jib
lead angle, imagine your C420 rigged, with the jib
trimmed in for going upwind. If the jib sheet points to
the bottom of the jib, you will be trimming the foot
more and the leech less. If the sheet points into the
middle of the jib, you will be trimming the leech and
foot about equally. If the sheets points up towards the
top of the jib, you will be trimming the leech more and
the foot less. On the old jibs, in order to get any
leech tension at all, the mast had to be set up with
almost no rake at all in order to get the clew high
enough to give any leech tension. With the newer sails,
the clew is higher and you get a much better lead angle
with more rake.
More rake is also good for opening the slot between the
main and the jib. Whenever the air leaving your jib is
flowing into your main, it is slowing you down. Having a
wider slot is better for windier conditions when you
need to depower, but a narrower slot will let you point
higher in conditions where you can keep the boat flat.
More rake = bigger slot + less power + better speed +
lower pointing. So if you are having trouble keeping the
boat flat, and are stuck pinching and not going fast,
rake back a little bit. If you are feeling underpowered
and have bad pointing, rake forward a little bit.
To measure rake, thread your main halyard end through
the end of a 25' or longer tape measure and hoist the
halyard to the top of the mast. With enough pressure to
pull the tape straight but not enough to bend the mast
tip, measure the distance from the top of the mast to
the top of the transom on the centerline. It is also
important to note that mast rake is measured with the
rig fully tensioned. Pull up your jib to full tension,
then measure the rake. If the rake measurement is too
big, lower the pins on your shroud adjusters, re-hoist
the jib, then re-measure the rake.
Main trim with the new sails is quite a bit nicer than
with the old ones. Basically, with the old sails, you
needed to pull the mainsheet hard to keep the top of the
sail sheeted in, but in doing so the bottom 2/3rds of
the sail would be badly overtrimmed. With the new mains,
the bottom 2/3rds of the sail is a little flatter. Now
you can trim hard enough to keep the top of the main
trimmed properly without overtrimming and closing off
the lower 2/3rds of the leech. In moderate winds it is
critical to trim the mainsheet hard to obtain pointing
and to keep the crew on the wire. In heavier winds, the
new sail shape allows the trimmer to obtain plenty of
twist in the leech for depowering by using the vang and
mainsheet together.
RIG TUNE FAULT FINDER
Here are some common symptoms and things you can do to
help solve them. You should ask yourself these questions
in order as the earlier questions are easier fixes and
more often incorrectly set.
Bad pointing
Is your mainsheet bridle too high?
Is your mainsheet trimmed tight enough?
Is your jib sheet trimmed tight enough?
Is your windward jib sheet trimmed tight enough?
Is your mast raked too far back?
Is your mast foot too far forward?
Do you have too much rig tension?
Bad speed
Is your mainsheet over trimmed?
Is your jib sheet over trimmed?
Is your windward jib sheet over trimmed?
Is your mast raked far back enough?
Do you have enough rig tension?
SETTINGS GUIDE
Here are some common settings for the new C420 sails.
All of these settings are based on the mast butt being
positioned 2 holes back from the forward-most hole.
These are based on combined crew weight of about 250
pounds. If you are much lighter than this, move up one
range (use the 12-14 setup in 9-11 knots of breeze). If
you are much heavier, move your setup down one range.
You should move down one range if there is significant
chop.
0-4 Knots
Rake: 203
Shroud Tension: 100 pounds
Centerboard: Full down
Mainsheet Bridle: Block sheave top 21 from board cap
Mainsheet Trim: Top batten telltale flying constantly
Vang: Loose
Outhaul: Slight horizontal wrinkles along boom
Cunningham: Loose but only a few horizontal wrinkles
Jib trim: Firm leeward sheet, slight or no windward
sheet
5-8 Knots
Rake: 204
Shroud Tension: 140 pounds (leeward shroud should be
just a tiny bit loose going upwind)
Centerboard: Full down
Mainsheet Bridle: Block sheave top 21 from board cap
Mainsheet Trim: Top batten telltale stalling often
Vang: Very slight tension
Outhaul: Slight horizontal wrinkles along boom
Cunningham: Loose to none
Jib Trim: Firm leeward sheet, firm windward sheet
9-11 Knots (this is the zone where you start to
transition to trapezing)
Rake: 203
Shroud Tension: 200 pounds
Centerboard: Full down
Mainsheet Bridle: Block sheave top 20 from board cap
Mainsheet Trim: Firm
Vang: Neutral in lulls, slight tension in puffs
Outhaul: Horizontal wrinkles along boom
Cunningham: Very slight tension
Jib Trim: Very firm leeward and windward sheet
12-14 Knots
Rake: 202
Shroud Tension: 230 pounds
Centerboard: Full down
Mainsheet Bridle: Block sheave top 17 from board cap
Mainsheet Trim: As hard as you can pull
Vang: Firm tension
Outhaul: Hard horizontal wrinkles along boom
Cunningham: Tensioned
Jib Trim: Very firm leeward and windward sheet
15-18 Knots
Rake: 1911
Shroud Tension: 300 pounds
Centerboard: Raised 1
Mainsheet Bridle: Block sheave top 16 from board cap
Mainsheet Trim: Pull hard until you start to heel too
much
Vang: Very firm tension
Outhaul: Hard horizontal wrinkles along boom
Cunningham: Hard tension
Jib Trim: Extremely firm leeward sheet tension, moderate
windward sheet tension
19+ Knots
Rake: 1910
Shroud Tension: 330 pounds
Centerboard: Raised 3
Mainsheet Bridle: Block sheave top 15 from board cap
Mainsheet trim: Pull hard until you start to heel too
much then ease, hike, trim
Vang: Very firm tension
Outhaul: Hard horizontal wrinkles along boom
Cunningham: Hard tension
Jib Trim: Extremely firm leeward sheet tension, slight
to slack windward sheet tension
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