NORTH SAILS J/24 Guide de démarrage rapide

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

ONE DESIGN WEST

Chris Snow . Vince Brun

619 226 1415

F 619 224 7018

[email protected].com

ONE DESIGN CHESAPEAKE

Max Skelley (410) 271-4282

[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.

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 (262) 275-9728 F (262) 275-8012

Sam Rogers

[email protected].com

Andy Burdick

andy@melges.com

Harry Melges

harry@melges.com

Gordy Bowers

gordy@melges.com

Jamie Kimball

jamie@melges.com

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.

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.

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.

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.

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

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 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: ____ / ____ / ____

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