UK Sailmakers J/24 Quick start guide

This J/24 Tuning Guide was written to help you get the best performance
from your boat. It represents years of sailing successes in the class as well as
computer analysis of the sail plan. The measurements and settings included
in this tuning guide are the fastest for your J/24 with UK Sailmakers sails.
Since crew, wind and sailing conditions vary, you may find different settings
that are best for you; however, by following these instructions you can be
confident that you are well set up to win the next regatta.
Always remember that besides having a prepared boat, nothing replaces
time on the water.
PREPARATION
Hull: The hull of a J/24
requires little attention
once it is faired. You
are not going as fast as
the boat’s capability if
you don’t have a faired
bottom. Wet sand the
bottom with 400 grit
sand paper, 600 grit for
the keel and then clean
it with soap before each
regatta. If you moor
your boat you’ll need a
different bottom finish.
Keel: One of the most
critical factors in speed
gains is keel shape.
Move the keel as far
forwards as the rules
allow and fair to mini-
mum thickness. A well
faired keel will provide
more lift, better pointing
upwind and less drag off
the wind.
Rudder: Keep it clean
as possible. Repair all
damage immediately,
especially on the trailing
edge.
Rig: There are several things to do before step-
ping the mast.
• Removethesparegenoahalyard
• Removetherunninglightandwiring.Cover
the holes with sail number martial or Teflon
tape.
• Cutmastbuttofftotheclassminimum
length. (Ask your class measurer.)
• InstallasmallsizeWindexwindindicatoron
the back of the masthead crane.
• Exitthegenoahalyardtothelowestsloton
the starboard side of the mast. Mount two
HarkenCamcleats(onebelowtheother)
just below the cutout. Pass the halyard to
a small ratchet block on the deck. Exit the
main halyard to the lowest slot on the port
side.
• Exitthespinnakerhalyardeightfeetabove
deck level and mount a camcleat just below
the cutout.
• Exitthetoppinglifttotheupperslotonthe
port side.
• Takeoffbothendsoftheboomandreplacetheouthaulsystemusinga6:1
Harkenblocksystemwith3/16”pre-stretchline.
• Beforesteppingthemast,cleanitandgiveittwocoatsofsiliconebased
marine wax.
UK SAILMAKERS J/24 TUNING GUIDE
INSIDE THIS GUIDE
Preparation 1
Weight 2
Tuning the Rig 2
Fine-tuning the Rig 3
ShroudTensionChart 3
Sail Trim 4
Deck Layout 5
Go Fast Tips 5

WEIGHT
Crew Weight: Always
race at maximum weight
allowedbytheclass:
400 kg. It is better to be
heavy in light winds than
to be light in high winds.
Since the J/24 starts to
heel at eight knots, you
will almost always be
hiking.
Boat Weight: Remove
everything from the
boat.Carryonlywhat
is required by the rules,
and each of those things
at minimum weight, like
the anchor and outboard
engine.
Crew Gear: You spend
hours removing things,
cleaning the boat, buy-
ing lightest shackles and
reducing the weight of
every piece of spare
equipment, which is all
the more reason to limit
what your crew brings
aboard. You can’t imag-
ine how much five bags
full of clothes can weigh.
Headstay Length: The
headstay length should
be the maximum al-
lowed by the class rules.
The measurement is
taken from the center of
the headstay pin at the
hounds to the intersec-
tion of the stem/sheer
line. The total length
should be 8670mm.
Becausetheheastayhole
in the bow of your boat is
approximately 65mm up
from the stem/sheer line
intersection, the actual
length of the heastay
from the centers of each
hole should be 8605mm
Mast Length: The mast
length should be mini-
mum allowed by the class
rules.Contactaclass
measurer as this is a com-
plicated process.
Your shrouds may be too
long to get adequate
rig tension if you have
to shorten the mast. If
this is the case, you may
be able to shorten the
shrouds by cutting the
turnbuckles.
Spreader Angle/De-
flections: First, cut the
spreaders to the mini-
mum length allowed by
the class rules, which is
760mm. Pull the spread-
ers back as far as they
will go using a string tied
around the shrouds at
the spreader tips. Then
measure from the middle
of the string to the aft
face of the mast. The
spreaders are at the right
angle when the measure-
ment is 165mm. Tape the
spreader ends to protect
the spinnaker and genoa.
After Stepping the Mast
Butt Position: The front
face of the mast should
be 2845mm from the
bottom bolt of the bow
stem fitting (looking
forward while in side the
boat) to the forward face
ofthemastatthe“I”
beam.Blockthemast
(at the partners) solid at
2910mm from the stem/
sheer line intersection for
themaximum“J”length.
Centering the Rig: Adjust
the upper shrouds hand
tight and center the top
of the mast. To find if the
mast is centered, hang a
bucket of water approxi-
mately one foot above
the deck from the genoa
halyard. The bucket of
water puts a constant
load on the halyard.
Next put a tape mark on
the halyard about two
feet above the bucket’s
handle. Then swing
the halyard out to the
starboard upper shroud
and put a tape mark
at the same height as
the one on the halyard.
Now put a similar tape
mark on the port upper
shroud. The last step is
to measure from the tape
marks to the base of the
chainplate on each side.
If one measurement is
shorter than the other,
tighten the shroud on
the long side until the
two measurements are
the same. UK Sailmak-
ers has a video of this
under the Education tab
ofthehomepage:www.
uksailmakers.com. Finally,
measure side to side to
find out if the mast is in
the middle of the boat at
the partners.
Tensioning for Base
Settings: Using a Loos
Tension Gauge Mode
B,tightentheupper
shrouds to 20 and the
lowers to 15 on each
side.
Adjust the backstay bridle
turnbuckles so that the
rollerisabout10”below
the connector plate. With
this measurement you
will need to have 21/4”
of pre-bend. Tighten or
loosen your backstay
TUNING THE RIG

untilyoureach-12ontheheadstay.
This will be the base setting. See the
photo to the right on how to measure
the tension of the forestay in nega-
tive numbers with your Loos Gauge.
If you get more than 21/4” pre-bend,
movethebuttposition1/4”forward.
Conversely,ifyougetlessthanthe
suggested prebend, move the butt
position1/4”aft.Youwillneedto
move the base forward or aft until you
get the desired pre-bend.
Pre-bend is measured holding the
main halyard directly to the goose-
neck, and then measuring from the
aft face of the mast to the halyard
at the spreader height.
Wind - Knots Uppers* Lowers* Stay* Genoa**
0 - 3 16 10 -12 6 - 8”
4 - 10 20 15 -12 3 - 4”
10 - 15 24 21 -5 1 - 2”
15 - 18 27 26 0 6”
18 - 22 29 29 +5 Jib (Leech straight)
22+ 29 29 +5 Jib (Leech twisted)
SHROUD TENSION CHART
** Distance from the genoa to the spreader. If the sea conditions are smooth (flat seas) in winds from
8upto16,youcantrimthegenoaoneinchcloserthanthenumbersontheabovechart.
Tip: Writethischartonthedeckwiththenumberofturnsyouneedtomovefromone
tension setting to the next.
* LoosTensionGaugeModelB
FINE
TUNING
THE RIG
Yourmainsailisdesignedtoperformin10knotsofwindwith21/4”ofpre-bend.In
heavy air, bend can be achieved through backstay tension, which will bend the upper
partofthemast,increaseheadstaytension,whichattensthegenoa.Becausewedon’t
wanttoattenthegenoainlightair,the21/4”ofbendmustbeachievedwithoutadd-
ing backstay tension. Once the wind lightens, you will ease shroud tension, which will
increase headstay sag and power up the genoa. As the wind picks up, you will progressively tighten the
lowers more than the uppers. The lowers will reduce pre-bend and stiffen the middle of the mast. Every
time you apply backstay tension, the upper part of the mast will bend, freeing the leech of the main and
flattening the genoa. When you want to gain power, ease the backstay.

SAIL TRIM
UPWIND OVERVIEW:Once
your boat is set up as out-
lined in this guide, there are
three sail adjustments that
will affect your speed more
than any others while sailing
towindward:genoasheet,
main sheet and backstay. If
you feel that you are lacking
speed, there is a 90% chance
that one of these three ad-
justments is wrong. If you are
slow, ease the sheets a few
inches, bear away a couple
of degrees, gain speed and
then try pointing.
Genoa Trim:Togetthe
genoa lead close to the
right position, move it so
that when you trim the foot of the
genoa tight enough to touch the
shroud turnbuckle the sail is one
inch from the spreader tip. This will
get you close. Next you’ll need to
move the lead so that you can trim
the sail according to the chart on
Page 3. With the genoa the cor-
rect distance off the spreader for a
given wind range, you can check
to make sure the lead is in the right
spot by heading closer to the wind
slightly. You want the upper tell-
tales to break a second earlier than
the lower ones. If the telltales break
evenly, move the lead back one
hole. If the upper telltales breaks
first by more than one second,
move the lead forward one hole.
Genoa Tracks:To fine tune the
genoa lead position, it is important
to have extra holes in the genoa car
track. Drill holes between the exist-
ing factory holes.
Genoa Halyard Tension:In light air,
the halyard should be tensioned for
no wrinkles along the luff (noth-
ing more than that). As the wind
increases, allow wrinkles in the luff.
This will move the draft aft, which
will improve pointing ability. With
more wind yet, tension the halyard
until the wrinkles disappear. Do not
over tension the luff of the sail. Use
the genoa cunningham to fine-tune
the luff.
If you cannot point, chances are
oneoftheseitemshasoccurred:
• Over-tensionedthegenoasheet
• Over-tensionedthegenoaluff
• Aloosemainsailleech
Jib Trim:Oncethewind
picksupover19knots,you
will need to change to the
little jib. Set the lead so that
the foot of the sail touches
the foot of the pulpit and the
leechreamins2”insdethe
spreader tip. If the wind goes
over 25 knots, move the lead
back1”totightenthefoot
and open the leech. With the
foot tight, the
leech should
be even with
the end of the
spreader.
When you first
change to the
jib, loosen the
shrouds one
scale setting.
Mainsail Trim:Untilyoustartheeling,maintaintheboomoncenterline.
In light winds pull the traveler to windward so the upper batten is 3-5
degrees open and the boom is over the boat’s centerline. As the wind
increases, start dropping the traveler and increasing sheet tension.
Whenthewindgetsupto10knots,thetravelerwillbeinthemiddleof
the boat. You will need to apply more sheet tension so that the top batten
points3degreestowindwardoftheboom.Whenyoureachmorethan13
knots, free the sheet a small amount and drop the traveler a bit.
Don’t let the boat heel too much. If you are
used to playing the sheet, you will probably
need to apply a lot of vang tension. This will
maintain the leech of the sail when you ease
the mainsheet. Don’t use the vang until you
start heeling. In puffy conditions, use the
backstay to depower and power up the boat.
Remember, do not try to point until you are at full speed. Also, if the boat
heels in a puff, don’t point to avoid heeling. Ease the sheet and let the
boat bear away a bit. You will end up in better position than a boat that
points and then slows down. A slow boat upwind will slide sideways and
not go where the boat is pointing.
Heeling:Upwind,never
heelmorethan10degrees.
If you start heeling more
than this, start reducing
power only after you are
sure that the crew is hiking
as hard as they can.

Continued from Page 4: When sailing off the wind, free the main sheet until the luff breaks and when on a
run, ease the boom to the shrouds. Set the vang so the upper leech is parallel to the boom. Don’t over tighten
the vang to the point that the boom breaks in heavy air. Remember to ease the vang at the windward mark if
you are vang-sheeting upwind.
Spinnaker Trim:Downwindyougainorlosethemost
distance. It is time to either attack the leaders or con-
solidateyouradvantageontheeet.Themax-size
Matrix Spinnaker is
a true runner, which
allows you to sail
lower than other
boats. Remember
that this sail is de-
signed to project its
maximum area, so
don’t pull the pole
too far aft. 80 de-
grees of apparent
wind proves to be
faster than the stan-
dard 90 degrees.
In over 8 knots, sail
the boat heeling to
windward as much
as10degreesto
help project the
spinnaker away from the mainsail and allow the boat
to sail deeper. Don’t do this if you have to steer too
much or if you start feeling pressure in the rudder.
Bringthetack(thecornerofthesailatthepole)
lower than the free-flying clew. NEVER allow the tack
• Sailatmaximumcrewweight.
• Sailtheboatasataspossible.
• Donotpinch.
• Settheshroudtensionforthewind
you are expecting in the first part of
the race.
• Whenindoubt,selectthemore
powerful option because it is easy
to depower the boat.
• Downwind,heeltheboattowind-
ward.
• Downwind,useasmuchcrew
weight as possible to steer the boat.
GO FAST TIPS
DECK LAYOUT
Rule:Simpleisfast.Trytoplaceallthecleatsas
close as possible to the mast. Remove the second-
ary winches. Use double winch handle pockets and
place them in front of the traveler.
Running Rigging:Newmaterialsappearinthemar-
ket on a reular basis; keep lines updated and at the
minimumsizeallowedbytheclassrules.
QUESTIONS
If you have any questions or comments, please
call us directly at UK Sailmakers Houston.
Pedro Gianotti
UK Sailmakers Houston
2031 Anders Lane, Ste J
Kemah, TX 77565
[phone]
[email protected]
to be higher than the clew. In almost all conditions,
set the tack about one foot lower than the clew. Se-
lect the ring that gets the pole more perpendicular
to the mast. Use the lower ring as long as you can.