NORTH SAILS J/24 Quick start guide

J/24 Tuning Guide
San Diego Designs
For any question you may have on tuning
your J/24 for speed, contact one of our J/24
experts listed below:
ONE DESIGN RHODE ISLAND
Tim Healy . Will Welles
401 683 7997
F 401 683 9121
[email protected].com
[email protected].com
ONE DESIGN WEST
Chris Snow . Vince Brun
619 226 1415
F 619 224 7018
[email protected].com
[email protected].com
ONE DESIGN CHESAPEAKE
Max Skelley [phone]
[email protected].com

NORTH SAILS J/24 Tuning Guide
San Diego Designs
Visit our web site at www.OneDesign.com for the latest J/24 news and tuning tips.
© North Sails One Design. All rights reserved. 1
Now check the deflection of the
spreaders. This is the distance between
the taut string between the spreaders and
the aft side of the mast. For the San Diego
model main this should be 160-165 mm.
If you mast has not been shortened
before measure down the mast from the
forestay fixing point as described in the
class rule 3.5.2 (7725mm down from
headstay pin center). You will need this
mark later to find out if your mast can be
shortened. You want your mast as short as
possible.
We want the headstay as long as
possible. To check this, attach the headstay
and hold it alongside the front of the
mast and make a mark on the headstay
corresponding with the mark in Rule 3.5.2
(7725mm down from headstay pin center).
Now is the time that you want to have
a class measurer with an approved jig
inspect your mast to make sure it is as
short as possible. The mark you previously
made on the mast must be no lower than
400mm above the sheerline abreast the
mast. We like to cut our mast so the lower
edge of the band is 405 mm above the
sheerline to ensure that our mast will
always measure in. See picture #3.
Picture 2. Step the mast and attach all shrouds
very loosely (except the backstay) leaving any mast
blocks out for the moment. Temporarily hold the
mast butt in place on the “I” beam with a pair of
vise grip pliers.
Next we need to make sure that the
mast is positioned as far aft at deck level
as possible. Have a friend hold the end of
your tape at the stem measurement point
and measure again straight to the lower
edge to the mast band. We want this
measurement to be as close to maximum
as possible, 2925mm. Chock the mast
at the deck to hold it in this position.
See picture #2 above for determining
measurement point at stem.
The next step is to place the butt of
the mast in the proper position on the “I”
beam down below.
North E Scow Experts
NORTH SAILS ONE DESIGN ZENDA
P [phone] F [phone]
Sam Rogers [email protected].com
Andy Burdick [e-mail]
Harry Melges [e-mail]
Gordy Bowers [e-mail]
Jamie Kimball [e-mail]
Thanks very much for purchasing your J/24
sails from North Sails we appreciate your
business. The following tuning guide is
meant to be a starting point in setting up
your boat for your new sails. If you have
any questions along the way we hope
you will give a call or send us an e-mail.
We are always ready to help you and your
crew to get the most out of your new sails.
Also please check our web site at www.
northsailsod.com. We have posted many
J/24 related articles there that may interest
you and help improve your understanding
of this great boat.
The tuning set up that follows is designed
to be as “all purpose” as possible. Like
many one designs the J/24 uses just a few
sails to cover a wide range of wind and
sea conditions. Set you boat up the way
we have described here and you will have
excellent speed in all conditions.
Measure the length of your spreaders
from the surface of the mast to the point
where the shrouds touch the end of the
spreaders and make sure the spreaders are
as short as possible, 760 mm.
Make sure the spreaders are swept back
the same amount on each side
– Tie a small string tightly between the
shrouds at the spreaders
– Set the mast on sawhorses with track
facing up and butt of the mast (with the
mast butt plug in place) resting on a horse.
– Using the back edge of the mast shoe as
your guide check to see the string between
the shrouds and aft edge of the mast shoe
are parallel. (See picture #1)
With the Mast Down
Picture 1
If not parallel you will
need to take the spread-
ers off and slide the
thru bar in your mast to
one side or the other to
compensate. If you do
not have a thru bar either
file down the stubby male
fittings or use spreader
adjusters to make the
sweep the same on each
side.
With the Mast Up

NORTH SAILS J/24 Tuning Guide
San Diego Designs
Visit our web site at www.OneDesign.com for the latest J/24 news and tuning tips.
© North Sails One Design. All rights reserved. 2
Picture 3
Using a friend to hold the end of the tape
measure from the top of the third bolt
holding the stem fitting on (inside the boat
up in the bow) to the intersection of the
front of the mast and the shoe the rides on
the “I” beam. This measurement should be
111 5/8”.
Picture 5
Hold the mast butt in place at this position
temporarily with a pair of vise grips.
Now tighten the upper shrouds to 24
on a Loos Model B tension gauge and the
lowers to 21. We get the uppers snug first
and then using the genoa halyard measure
down to the chainplates on both sides to
be sure the mast is centered in the boat.
Be sure to sight up the backside of the
mast to be sure it is straight.
Now we will check to make sure the
mast butt is in the right place. With the
backstay disconnected measure the
tension on the headstay. The tip of your
gauge should be about 20-30 mm from
the close side of the headstay wire. See
picture #4 below.
Picture 4
If your headstay is tighter than this you
will need to move your butt aft slightly if it
is looser move it forward slightly. Be sure
to check and adjust the tension on
the shrouds before you recheck the
headstay tension.
At this point your mast should be set up
with 1- 1.5” of prebend in the mast. To
check this simply hold the main halyard at
the gooseneck and sight up the backside
of the mast. If this is not the case you
will need to back and recheck your
measurements.
As we mentioned before, the J/24 has just
4 sails to cover the entire wind range the
boat is raced in. For the best performance
in each condition we adjust the tension on
the shrouds depending on how much wind
there is. As the final step in setting up your
boat fill in the attached tuning chart with
how many turns of the turnbuckles it take
to get from one setting to another. We
often adjust our shroud tensions between
races (it is against class rules while racing)
and it is impossible to the get accurate
readings while the sails are up of the boat
is in any waves at all.
SAN DIEGO J/24
TUNING CHART
New Loos Gauge Pro Model PT2
Wind Speed
(knots)
Uppers
Tension
Lower
Tension
0-5 15 12
6-9 16 13
10-13 (BASE) 19 17
14-17 22 19
18+ 25 26
SAN DIEGO J/24
TUNING CHART
Old Loos Gauge Pro Model B
Wind Speed
(knots)
Uppers
Tension
Lower
Tension
0-5 18 12
6-9 20 15
10-13 (BASE) 24 21
14-17 27 24
18+ 30 31
Tuning Chart

NORTH SAILS J/24 Tuning Guide
San Diego Designs
Visit our web site at www.OneDesign.com for the latest J/24 news and tuning tips.
© North Sails One Design. All rights reserved. 3
Special note on the backstay: As you
adjust the tension of your side shrouds up
and down you will notice that the backstay
gets tighter or looser. Each time you adjust
your side shrouds be sure to adjust the
two smaller backstay turnbuckles so that
the blocks riding on the backstay bridles
stay 6-8” below the “y’ in the backstay
when the tension is off. This is very
important to make sure the headstay can
get tight and loose enough depending on
the conditions.
You are now ready to start sailing!
Follow these guidelines to set up and trim
your sails.
MAINSAIL
OUTHAUL
0-4 knots: Clew should be ½ “ from black
band
4+ knots: Clew should be at band
CUNNINGHAM
No cunningham until about 12 knots,
then tension until wrinkles in luff are just
removed.
VANG
Upwind keep loose to 8 knots then tension
to remove all slack above that. Above 15
knots tension very hard so boom does not
rise at all when the mainsheet is eased.
Downwind tension so top batten is parallel
to boom.
TRAVELER
Keep all the way up on weather side until
crew is all sitting out on weather side with
legs out. As soon as crew is on weather
rail with legs over, drop down 2”. Then
drop it down as far as the middle of the
track to keep the boat flat. If you have to
drop below middle to keep boat flat put
on some backstay and keep traveler in the
middle. Play traveler in puffs to keep boat
flat as wind builds. We do not like to sail
with traveler below ¾’s of the way down.
BACKSTAY
Use to control fullness on main and genoa.
Leave loose until about 8 knots. Slowly
tighten as breeze builds to depower
boat. At it’s tightest, it will be all the way
down to the top of the pushpit. A small
adjustment (1-2”) can have a big effect
here. Be sure to adjust the backstay
turnbuckles when adjusting the side
shrouds.
MAINSHEET
Tension mainsheet so top batten is parallel
to the boom and the top telltale is flying
50-60% of the time up to 10 knots of
wind. Above that the top telltale should be
flying all the time because now the top of
the main will be flatter.
GENOA
With the genoa there are three major
things we are concerned with, having the
lead in the proper position, having the
genoa halyard set right and getting the
sheet tension right.
HALYARD TENSION
We want to the halyard set so the luff of
the genoa has just a hint of wrinkles in
it. The reason is that we have found that
it is better to have the halyard too loose
rather than too tight. In light air we want
to be sure that the luff is nice and loose.
As the wind builds, we tension the halyard
enough that the cloth along the luff of the
genoa is smooth.
It is important to have a mark for your
genoa halyard near the cleats or stopper
that keep it in position. We mark off ½”
increments to make it easier to duplicate
fast settings.
LEAD POSITION
Note that it is important that you have
drilled out an extra set of holes between
each of the factory-drilled holes in your
genoa track. The standard spacing is too
far apart to be workable.
Having the lead in the correct position is
critical for good speed. In moderate breeze
(4-8 knots), trim the sail in and position
the lead car so that the sail touches
the spreader and the chainplates or
turnbuckles at exactly the same time. Mark
this position. This will be your neutral
point for your jib lead.
SHEET TENSION
We check the sheet tension by judging
how many inches the sail is trimmed away
from the end of the spreader. Generally we
never trim the sail tighter than 1” from the
end of the spreader.
Sail Trim

NORTH SAILS J/24 Tuning Guide
San Diego Designs
Visit our web site at www.OneDesign.com for the latest J/24 news and tuning tips.
© North Sails One Design. All rights reserved. 4
As the above chart shows it is important
to change your settings depending on
the condition. Be aware that as the
wind builds and dies you will need to be
constantly adjusting the tension on the
genoa sheet.
CLASS JIB
For fine-tuning the lead position, drill two
extra holes between each set of factory
holes in the jib track. Start with the jib
lead block positioned at the chainplates
and fine tune the lead position from there.
Unlike the genoa the luff of the jib should
always be smooth. Be careful, you can in
moderately heavy air get the luff too tight.
The luff of the sail should break evenly
up and down. If the sail breaks high first
move the lead forward, low first move the
lead back. Check this carefully and make a
mark on the deck in the correct spot.
Sheet tension is critical. We like to adjust
the tension on the jib sheet to balance out
the helm of the boat. If the boat has a bit
of weather helm trim the jib slightly to pull
the bow down. If the boat has leeward
helm ease the jib slightly. Keep in mind
that you only need to change the tension
on the sheet very slightly (1/2” increments)
to have a real effect on the trim of a high
aspect sail like the jib.
SPINNAKER
The spinnaker should be at full hoist at all
times. The general rule of trim is to allow
2-4" (50-102 mm) of curl in the luff of the
sail. The outboard end of the pole should
be even with the free floating clew and the
pole should remain perpendicular to the
apparent wind. Use the upper pole ring for
most conditions. If you are going slow try
raising the pole a couple of inches.
DOWNWIND — LIGHT AIR
Concentrate on good communication
between helmsman and spinnaker trimmer.
The goal is to sail as low as possible
while still maintaining good pressure in
the spinnaker (measured by tension on
the sheet). Try not to sail too high which
translates into longer distances, but do not
sail too low at a slow pace. Be careful not
to pull the pole too far aft which flattens
the spinnaker.
DOWNWIND — HEAVY AIR
Be careful not to square the pole back too
far as this makes it easier for the spinnaker
to roll out to weather. Do not let the clew
of the spinnaker go past the headstay.
Keep most of the crew hiked on the
leeward side in order to sail low and not
risk rolling to weather.
DOWNWIND TIPS
Pole height is important and changes
in increments of 1" (25 mm) have a big
effect on the spinnaker. The break the sail
should curl evenly from top to bottom . If
the spinnaker breaks high, the pole is too
low and should be raised. If the break is
low, the pole is too high and should be
lowered.
Whether or not you use tweakers (or
twings), an efficient foreguy system is
crucial. Every up and down, or back and
forth motion of the pole (and hence the
spinnaker) is wasted energy; that energy
will not be pulling the boat forward.
An efficient system for launching and
retrieving the spinnaker is a must. We
recommend a deep cockpit launching bag.
Call us if you would like one made for your
J/24.
MAINSAIL SETTING CHART
Wind Speed Traveler Backstay Top Batten Angle Outhaul
0-6 knots All way up None Closed 3 degrees In ½”
7-12 Down 3-4” ¼ on Closed 3 degrees to parallel Max. tight
12-18 Middle ½ to ¾ on Parallel to open 3 degrees Max. tight
18+ Below CL 2-3” Max on Open 3-6 degrees Max. tight
GENOA SETTING CHART
Condition Lead Halyard Sheet
0-6 flat 1 aft of neutral Wrinkles 3-4” off spreader
0-6 choppy On Neutral Wrinkles 3-6” off spreader
7-13 flat On Neutral Just Smooth 2-3” off spreader
7-13 choppy 1-2 holes fwd. Wrinkles 2-4” off spreader
14-18choppy 1-2 holes fwd Smooth 4-6” off spreader
18+ On neutral Tight 6-8” off spreader

NORTH SAILS J/24 Tuning Guide
San Diego Designs
Visit our web site at www.OneDesign.com for the latest J/24 news and tuning tips.
© North Sails One Design. All rights reserved. 5
In conclusion:
Always sail the boat as flat as possible
except for very light air
Sail as close to max weight limit of 400
kgs as possible.
Do not be afraid to change settings if
you are slow.
Keep a tuning chart and use it.
Have open positive communication on
board.
Sail fast and have fun!
Your North Sails are constructed out of
the best materials on the market today.
We make sure of this by testing every roll
of cloth we use. Through proper care and
maintenance your sails will give you the
performance you have come to expect
from a North Sail
The most important factor for a long life
for your sails is to watch them for signs
of wear and tear in high load and chafe
areas. Be sure to wash the sails off with
fresh water and dry the sails thoroughly
before storing. A dry, mild climate is best.
Excessive heat can cause problems with
the sails due to the possibility of shrinkage.
It is best to roll the mainsail, genoa, and
jib.
MAINSAIL
When hoisting and lowering the sail try
to minimize the amount of creasing or
wrinkling of the sail. Every time the sail
gains a crease the cloth breaks down that
much faster. Always have someone contain
the leech and luff during these procedures.
The battens can be left in the sail without
any problems. Be sure to roll the sail down
the leech so that the battens will not twist.
This could cause damage to the battens.
GENOA
With today's Mylars becoming softer this
process has become more difficult. When
folding, creasing can develop from folds
and accelerate the breaking down of the
Mylar. The worse case scenario is for the
sail to be rolled and then folded.
JIB
When rolling the jib keep the battens
perpendicular to the leech. Pay special
attention to the battens and batten
pockets for wear and tear. Since this sail is
manufactured from yarn tempered Dacron,
problems can arise due to mishandling.
SPINNAKER
The spinnaker is fairly straight forward. Be
sure to repair all tears and pulled stitches.
Folding the sail when storing is best.
This tuning guide only begins to cover all
there is to know about racing the J/24.
The J/24 team at North One Design has
prepared a professional, in depth J/24
racing clinic that you and your fleet will be
interested in learning more about. In the
course of an evening or weekend you will
learn more about racing your J/24 than
you could possibly learn in a season of
racing on your own.
Please call you nearest North Sails One
Design International loft for complete
details!
At North Sails we are constantly striving to
make our products better. If you have any
comments on this tuning guide and how it
could be improved for your purposes we'd
love to hear from you. Please give us a call
or drop us a line.
TENSION GAUGE CONVERSION
CHART
Over the past few year Loos Co. has
introduced it's new style PT-1, 2 and 3
professional tension gauges to the market.
Since many of us are replacing our older
model A and B gauges with these new
models we are posting the following
conversion chart for your convenience.
MODEL A MODEL PT-1
3/32 1/8 5/32
5 6
10 9
15 12 14
20 16 16
25 20 19
28 23 21
30 22
35 27 25
38 30 28
40 33 30
42 33
44 36
45 38
46 39
47 40
Model B Model PT-2 PT-3
3/16 7/32 1/4 9/32
10 11
15 13
18 15
20 16 18
22 18 20
24 19 22
26 21 24
28 23 25
30 25 27 25
32 27 29 27
34 29 31 29
33 31
36 33 6
37 36 7
37 9
10
11
12
14
16
18
20
25
Appendix A
J24 Sail Care
Appendix B
J24 Racing Clinics

NORTH SAILS J/24 Tuning Guide
San Diego Designs
Visit our web site at www.OneDesign.com for the latest J/24 news and tuning tips.
© North Sails One Design. All rights reserved. 6
NORTH SAILS ONE DESIGN QUALITY
CONTROL CHECK
MAINSAIL JIB
Corners Corners
Cunningham Battens
Tack Slug Cunningham
Leech Cord Telltales
Royalty Leech telltales
Numbers Leech line
Country Code Royalty (stitched on)
Battens Measurement sticker at head
Leech Telltales North Logo
Insignia (stitched on) Bag
Measurement sticker at head
North Logo
Bag
GENOA SPINNAKER
Corners Corners
Cunningham Numbers (one side)
Telltales Country Code (one side)
Leech telltales Royalty (stitched on)
Leech line Measurement sticker at head
Luff Hanks North Logo
Tacking Line Bag
Spreader and stancion patches
Country Code and Numbers
Royalty (stitched on)
Measurement sticker at head
North Logo
Bag
Checked by: _____________________
Date: ____ / ____ / ____