TUNE YOUR FOR OUTRIGHT SPEED

J/24 Tuning Guide Rev R05 Congratulations on your purchase of The other reason tuning (here we mean crews, but must stand up to near gales North J/24 sails. We have been building rig tuning) is important with the J/24 too. J/24 sails since the boat’s inception with is that we are asking a very limited the goal of providing our customers with inventory to perform over a very wide Picture a starting line of 50 to 80 ultra- fast, easy to use, and durable sails. You range of conditions. J/24’s are commonly aggressive racing fanatics and you can can follow this guide with confidence, raced from 0-30 knots of wind and to see how Darwin’s theory of evolution knowing that North Sails’ clients have ask four sails to cover that entire range applies to sailboat racing. Very often won more World, Continental and is really asking a lot. We need the sails one boat length separates the front National Championships than all our to be board flat in heavy air yet full and row from the cheap seats at the start, competition combined. powerful in the light stuff. so attention to boat preparation has become imperative to survival in the This guide is the result of years of testing, The best way to accomplish this is class. Following is our list of preparation tuning and practical racing experience. through aggressive adjustment of the ideas that will allow your team to stay While we can’t guarantee that you will tensions (which directly affects competitive. start winning immediately by following sail shape) and sail trim changes through this guide, we can assure you that you the wind range. will be taking a very big step in the right direction. Please read this guide entirely The Straight before using your sails for the first time. Introduction Tuning System We urge you to pay special attention to the section on sail care in order to Our Sail loft in Portsmouth has been BOAT PREPARATION prolong the life of your sails. obsessed with J/24 sailing for the last Boat preparation is critical in the J/24 decade. During that time we have class. Sails, layout, keel and rudder If you have any questions please feel free experimented with hundreds of sails, shape, and mast tuning all share equal to contact us. We are here to help you dozens of deck layouts, a spectrum importance. Often newcomers to the get the most out of your J/24 sailing. of keel shapes and every possible class prioritize one of these factors as combination of rig settings. As any of you “the project I’ll tackle this year”. These WHY TUNING IS IMPORTANT who have been talked into sitting on the are also typically the same people who rail for us can attest, tuning sessions are sell their boats for a major financial loss The J/24 is the most successful keelboat typically dull affairs. But we have been at the end of one season of mediocre design in the world. However, like many rewarded by watching our sails win 5 and poor finishes. To be competitive in other boats it has flaws. Most of the of the last 8 World Championships and the J/24 ranks, you must tackle all these tuning we do, especially in the boat hundreds of National, Regional and Local important factors. preparation area, is to overcome these titles. flaws and make the boat faster through The J/24 has a balance problem. Most the water. We have learned how to tune and of our tuning features are attempts fine-tune the J/24 in an attempt to fool to alleviate the lee helm that J/24s A characteristic of the J/24 is the boat four sails through a range that could be experience in less than 10 knots of wind. develops lee helm in light air. A boat covered by eight. The 150-percent genoa that has lee helm will be slow upwind, must be a drifter in light slop, and flat and KEEL because it will not point and will be slow twisty in 18 knots. The main needs to be Over the years we have found that due to the increased drag of the rudder flat enough to avoid excessive backwind, the minimum keel offsets will provide always needing to be forced off centerline but not invert when the big breeze and adequate lift upwind and reduce drag to keep the boat going upwind. We need comes on. The is downwind. When fairing the keel to to modify the boat and it’s in asked to float in the drifters and reach minimum thickness it should also be order to reduce this lee helm as much as in 25 knots. The 100-percent blade moved forward by removing material possible. is brought well below its range by light from the trailing edge and building

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J/24 Tuning Guide Rev. R05 up the leading edge. This moves the get the center of the sail plan as far aft as backstay tension. Having the step too underwater center of effort forward, possible. Measuring the mast length and far forward (the most common problem) helping to reduce lee helm. headstay is very critical, and the class creates an over-tight headstay in light rules should be referred to in order to air, and too full a . We position RUDDER do this accurately. We also suggest you our mast base by crawling around the The rudder should also be minimum only cut the mast to within 5 mm of the inside of the forward cabin and taking thickness, but old rudders don’t stand minimum, as different measurers always two measurements. First, find the stem up well to being faired—that’s how get different lengths. Complete this fitting (the metal plate in the very they break. Since 1986 the rudders have process well before your next regatta as of the boat). Locate the 3rd bolt down come from builder Tillotson Pearson at your shrouds may need to be shortened on the fitting. Measure from beside that minimum thickness, so buying a new too. bolt, (where the bolt meets the hull) to rudder is better than fairing an old one. the “I” Beam on which the mast sits. The angle must be fixed Put a mark on the beam at 2,730 mm. HULL depending on your mainsail’s type and From that line place the front of the In general, the bottom should be smooth luff curve. For our sail we move the mast exactly 130mm from this mark on and fair. The class rules allow factory spreaders forward for 160-165 mm of the “I” beam. We scribe a line into the imperfections to be filled. Grinding down deflection, stiffening the center of the beam so that we only have to make the highs in the gelcoat is not allowed. Wet mast to help get headstay tension in measurement once. sanding to 600 grit adds the finishing heavy air. This also allows a mainsail to touches to your fast underwater shape. be cut with less luff curve, giving the sail Now you can tighten your uppers to 20 plan greater projected area. There are on the scale of a Model B Loos gauge MAST PREPARATION three styles of spreader bracket used. and leave the lowers slack. To center Rig preparation is quite simple and The latest “thru-bar” types ensure the the mast, first measure back from the can be completed in a few hours. most accurate setting for the longest stem fitting to a point on both rails First, remove the spare genoa period of time to maintain the 160- perpendicular to the front face of the since nearly all J/24s sail with hanks 165 mm setting, and any mast can mast. Measure from the marks to the on the . If your need be retrofitted to this type of spreader center weld on the mast to determine replacement, we recommend minimum- bracket. The other male-female and if the mast is centered at the deck. You diameter Spectra mainsail (8 mm) and female-male brackets require shims to may need to make custom shims to genoa (6 mm) halyards, both with spliced hold the spreaders in the correct position secure the mast toward one side of the wire tails for less weight and low stretch. or they will shift aft quickly. mast partners. the genoa halyard A 6 mm Dacron spinnaker halyard is at a position where, holding the adequate. Depending on your local Finally, the fully prepared mast can be with two fingers and your thumb, you regulations and plans for the boat, you stepped and the mast butt fixed. We sail can just touch the mark on the rail with can take out the mast lights and wiring. with the maximum J dimension (2925 the halyard shackle. Repeat the process On older Proctor mast the wiring conduit mm - see class rules for measurement on the other side. Next, adjust the should be taken out by removing the five points); most mast-partner blocks will uppers until the mast is centered. Now pop rivets on the front side of the . have to be altered to achieve maximum adjust the lowers to straighten the mast. This allows the mast to bend properly in J. We use this maximum-aft setting to The backstay should be loose during the lower third. You should also install a move the center of effort aft and open this process, with the wire blocks about masthead fly—we recommend a dinghy- up the slot between the genoa and main. a foot below the intersection of the split size Windex. wires. With no backstay tension there The mast-butt position is a critical speed should be 2.25 inches of pre-bend. The mast needs to be raked back as far factor. Stepping the mast too far aft as possible to help the lee-helm problem. will add too much pre-bend, resulting A maximum-length headstay combined in an over-sagged headstay and a with a minimum-length mast helps to mainsail that will invert with just a little 2

J/24 Tuning Guide Rev. R05 SHROUD TENSION with five, right around the maximum shackle is fixed to the stem head for the Sail shape is governed by shroud tension. crew weight of 880 lbs. Teams with headsail . A jib is led We use the accompanying chart to move lighter people have been sailing with six from a check on the side of the the four sails through the entire wind to get to the maximum weight. stem fitting through the Cunningham range. As the shrouds become tighter in and dead ended into the snap the windier conditions, the turnbuckles Our philosophy on boat set-up is “the shackle. This creates a 2:1 purchase. The on the split backstay bridle need to be simpler the better”. Simplicity breeds 3:1 purchase is now situated in the center hand-tightened so you can get adequate success, fewer errors and breakdowns, of the main hatch cover. (See diagram for tension, and then loosened again in light and saves money. A simpler boat details). The is never released air to allow the headstay to sag when also makes it easier to teach new or lowered with the pole, only fine-tuned the backstay is off. Again, the numbers crew members their jobs. We think it when the pole is set. The permanent listed in the box correspond to the large is important to get the whole team foreguy remains attached to the topping size “B” Loos tension gauge settings. involved in creating the deck layout, lift and is only led directly to the pole in giving each crew the responsibility for his light, sloppy conditions. Since our twing DECK LAYOUT/CREW POSITIONS section of the boat. lines are forward of the shrouds, the In setting up your deck layout, you acute angle formed between the end of should consider the strength of your Starting at the bow of our boat, the the pole and the twing prevents the pole crew and their number. Most of us sail tack horns are taken off and a snap from lifting up when the twing is down, eliminating the need for the foreguy in most situations.

SHROUD TENSION GUIDE We move all the halyards forward to the mast, which diminishes around-the- True Wind Strength Knots Uppers‡ Lowers‡ mark chatter. With the spinnaker halyard eight feet off the deck on the starboard LIGHT 0-9 20 15 side of the mast, the bow person hoists On long Olympic courses we sometimes use this as an all-purpose setting, allow- the spinnaker and then reaches down ing for a light breeze to build and still be in the rig setting’s range. to release the genoa halyard. The next person back handles the twings, , MEDIUM 10-13 24 21 and main Cunningham, and monitors Pre-bend is reduced to 2 inches. This allows for necessary backstay tension and compass headings with the digital resulting headstay tension to begin depowering the rig in the puffs. compass on the mast. With the halyards cleated on the mast, the and MEDIUM HEAVY 14-17 27 24 all the cleats are eliminated from the This setting is one that we use any time significant depowering is necessary. middle of the deck, making it an “almost Lighter crews will go to this setting earlier and find that they are able to sail flatter fun” place to cross during maneuvers. and faster than if they stay at 24 and 21. Cuts and bruises are not fun, and equipment only complicates the boat. HEAVY 18+ 29 29 Moving aft, we place spinnaker trimming Whether at the top end of the 150 or into the 100, it’s windy and the backstay duties and tactics on the third person. needs to be pulled on hard. With this shroud tension the lowers have pulled out The jib trimmer windward-sheets the nearly all the pre-bend, creating a very stiff mast that can be bent by the backstay genoa and helps with the trimming to flatten the main. The headstay in turn gets extremely tight with the lowers and downwind. We moved the winches backstay forces working against each other. forward far enough to allow the trimmer to face forward, which helps with ‡ = Large size “B” Loos Tension gauge scale. trimming and . This also gives 3

J/24 Tuning Guide Rev. R05 the helmsman room to steer with his GENOA (Remember, these trimming distances weight father forward. We have no jib The 150% genoa covers the wind range are to check the lead position, not for cleats because the should never be of 0-17 true knots, a range that could sailing upwind). cleated. be covered by three sails. In conjunction with the proper rig tune, the genoa You need to get creative with your lead The helmsman’s area or “office” has is affected by halyard tension, lead position in between shroud adjustments, been tweaked for 10 years—it may position, and sheet tension. as the mixture of twist induced by look basic, but we’ve tried it all! The 2:1 easing the sheet or by moving the lead backstay is led across the cockpit and Halyard tension affects the position aft is critical for maximum speed. The angled to where the helmsman sits of the sail. On our genoa, the draft is rule of thumb is to twist by moving upwind. The dual handle holders designed four percent farther forward the lead back to depower in flat water, are for the two handles he uses to grind than a normal light-air genoa, so in light and twist by easing the genoa sheet in in the genoa after tacks, and the genoa air we slide the draft back by sailing with choppy water. Check the trim chart for should be fine-tuned constantly. If the 1/2-inch scallops between each luff hank. the Genoa’s proximity to the spreader in helmsman of your boat has difficulty These wrinkles look pretty ugly, but they different conditions. tacking and grinding the winch, pass the allow the draft to move aft to 44 percent, handle forward to the tactician to carry the proper position for light air. As the MAINSAIL through the tacks. breeze builds, halyard tension should Mainsail trim is rather straightforward. be slowly tightened until the wrinkles Again, the shroud tension and mast step We’ve just finally switched to the Harken disappear in 12 knots true and up (usually position have the most to do with your self-tacking car for the main traveler when whitecaps just appear on the mainsail shape. Once the rig is set, the and we really like it. We’ve also switched water). A mark on your halyard with a mainsail is trimmed (or overtrimmed) to back to a basic 4:1 mainsheet instead numbered scale will help you duplicate assist the balance of the boat. We trim of the 2:1/4:1 system. The straight 4:1 fast settings. Since we don’t have any the mainsail tighter on a J/24 than any system is slower at mark roundings halyard winches, we use the genoa other type of boat we’ve ever sailed. In but allows more throw when traveler Cunningham to fine-tune the luff tension up to 13 knots, the top batten points as sheeting in heavy air. This cockpit set- and the draft position if conditions much as seven degrees to windward of up gives the helmsman plenty do to change in the middle of a beat. parallel with the , and the telltale (backstay, mainsheet, traveler, genoa on the top batten is stalled as much as trim, and steering) which is why we feel The genoa lead has three basic settings. 50 percent of the time— but the boat it’s important to pass the tactical role Stock genoa tracks should have two doesn’t seem to slow down: it just points forward to the crew. new car holes drilled between each higher! factory hole, allowing you to adjust the genoa lead in half-hole increments. Position the traveler to windward and Sail Trim When using the light-air shroud center the boom in very light air. Once setting in under 5 knots of wind, the the crew is all , the traveler slowly Once your boat is set up properly, the car should be positioned so when the goes down until the car is centered as final piece to the puzzle is your sail genoa is overtrimmed the leech hits the boat becomes overpowered. At trim. There are three sail adjustments the spreader while the foot remains this point it’s important to remember that will affect your upwind boat one inch off the chainplate. In medium that J/24s hate to heel, and should be speed more than any other: Backstay air, move the lead aft one hole. At this sailed flat, or with less than 12 degrees tension, mainsheet tension, and genoa setting the overtrimmed genoa will of heel. Once the traveler is centered, sheet tension. All these controls share touch the chainplate and spreader tip the backstay/traveler trade off begins. In equal importance and require constant simultaneously. At the heavy air setting around nine knots of wind, we pull on six attention. (one more hole aft) the over-trimmed inches of backstay (on the wire bridle) to genoa will touch the chainplate while the every two inches we drop the traveler. leech is two inches off the spreader tip. 4

J/24 Tuning Guide Rev. R05 Many times you will depower by back to traveler sheeting and get the reaching and running legs in strong dropping the main traveler, and the main top batten back to parallel to cover the breezes. If we ever get caught on very will flog. Avoid this by easing the genoa 17 to 21 range. In over 21 knots true, we tight reaches, we over-lower the pole to sheet so that the leech of the genoa is become overpowered again and shift open up the leeward leech. In general at 6-8 inches off the spreader tip. This back to vang sheeting. the pole end clew should be kept slightly allows you to drop the traveler lower lower than the leeward clew. Keep the and keep the boat on its feet without BLADE JIB pole squared back as much as possible losing pointing. Also remember that the Since it’s always windy when racing for the jibing angles. A low, squared backstay affects the leech tension of with the blade jib, the sail is easy to set pole helps project the extra area in the the mainsail dramatically, so every time up. The halyard is always tightened just lower leeches of the pear-shaped J/24 the backstay is adjusted, the mainsheet enough to pull out the scallops between spinnaker. must also be adjusted. the hanks. The lead is set at one of two holes; an all-purpose setting, used 85 The outhaul is a simple adjustment: percent of the time, and the “death hole”, Summary We ease it two inches forward of the 1.5 inches farther back. It needs to be The key to successful J/24 racing is not black band in under five knots of wind, really windy to go to the death hole, but the memorization of this information, one inch in 6-13, and right to the band if you’re overpowered you have to do but the understanding of it. Why is in anything over this. The Cunningham whatever you can to keep the boat flat. mast rake so important? Why does a is rarely touched on our main. We sail particular deck layout work, and will it with a floating tack (a sail slide webbed The all-purpose lead sets up the sail with work for your crew? Why do we sail with on the tack of the sail) that can move up six inches of depth from tack to clew, wrinkles in the luff of the Genoa in light and down the luff groove. The halyard is with the jib leech two to four inches air? You can only go so far by copying simply cleated with the headboard at the inside the spreader tip. With our jib, the others without understanding why the masthead band, and we only pull on the center of the jib lead block is one inch technique is fast. Cunningham in overpowering conditions forward of the chainplate. At the all with just enough tension to smooth out purpose setting, sheet tension should The J/24 is continuously optimized to a the luff wrinkles. be varied so that the leech moves from high level. The product of this enhanced 3 inches inboard of the spreader tip in 17 performance is a boat that is far more Once the traveler and backstay options knots to 3 inches outboard in 25 knots. pleasurable to sail. Stepping up to the are exhausted and the boat is still In the aft hole the leech will be trimmed next level of competitiveness will only overpowered, we go to vang sheeting. As between even with the spreader tip to 6 make your racing experience more fun the wind picks up, the top batten should inches outboard. and worthwhile. go from seven degrees to windward in up to 13 knots, then parallel to the boom SPINNAKERS At North Sails we test and tinker on in 13 to 16 as the crew starts to hike J/24 spinnakers are an odd shape. The a year-round basis in an attempt to and the boat starts to develop weather rules measure 1/4 girth (head girth) and improve the speed, durability and ease helm naturally, then twisted five degrees mid girth the lower half of the sail can of use of our sails. We do our best to off parallel when sailing at the top end be pushed out as far as the shaping will share anything that we learn with other of the genoa with the traveler down allow. These sails are also deeper than members of the J/24 class. If you have and the backstay on. Vang sheeting is most all-purpose spinnakers, as J/24 race any questions about our sails or tuning used in the twisted mode because the courses rarely have super-tight reaches. procedures, or have found that some traveler is too short. We tighten the vang A deep spinnaker is an easy spinnaker other technique that works better, enough to control the leech tension at to trim, with forgiving leech shapes, so please feel free to give us a call. the five-degree setting, allowing the most of the normal spinnaker techniques boom to travel beyond the end of the work in this class. We put the spinnaker traveler, depowering the sail plan. Once pole on the lower ring in up to 12 knots, the 100-percent blade jib is up, we shift then switch to the top ring on broad 5

J/24 Tuning Guide Rev. R05

UPWIND SAIL TRIM

Wind Strength 0-4 5-10 11-15 16-19 20-24 25+

JIB SELECTION 150 Genoa 100 Jib

GENOA FOOT 5 3 2 6-8 Use jib Inches from chain plate GENOA LEECH 5 3 2 6-8 Use jib Inches from spreader tip

JIB HALYARD TENSION Wrinkles Slight wrinkles Smooth

OUTHAUL 2 1 0 0 0 0 Inches from band

TRAVELER / VANG SHEETING Traveler Vang / Traveler Vang

TOP BATTEN TWIST When top batten points to windward, Parallel to 5° Clsd Parallel 5° Open leech is closed; when twisting to leeward, leech is open.

TRAVELER Middle 3-6 8-12 12-18

BACKSTAY Loose 6 8-16 20-30 20 24+ Wire blocks, inches pulled down bridle

Sail Care areas. Be sure to wash the sails off with contain the leech and luff during these fresh water and dry the sails thoroughly procedures. before storing. A dry, mild climate is Your North Sails are constructed out of best. Excessive heat can cause problems The battens can be left in the sail the best materials on the market today. with the sails due to the possibility of without any problems. Be sure to roll the We make sure of this by testing every roll shrinkage. It is best to roll the mainsail, sail down the leech so that the battens of cloth we use. Through proper care and genoa, and jib. will not twist. This could cause damage maintenance your sails will give you the to the battens. performance you have come to expect MAINSAIL from a North Sail When hoisting and lowering the sail try GENOA to minimize the amount of creasing or With today’s laminates becoming softer The most important factor for a long life wrinkling of the sail. Every time the sail this process has become more difficult. for your sails is to watch them for signs gains a crease the cloth breaks down When folding, creasing can develop from of wear and tear in high load and chafe that much faster. Always have someone folds and accelerate the breaking down

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J/24 Tuning Guide Rev. R05 of the laminate. The worse case scenario Tension Gauge Conversion Chart is for the sail to be rolled and then folded. Over the past few year Loos Co. has introduced it’s new style PT-1, 2 and 3 professional JIB tension gauges to the market. Since many of us are replacing our older model A and B When rolling the jib keep the battens gauges with these new models we are posting the following conversion chart for your perpendicular to the leech. Pay special convenience. attention to the battens and batten pockets for wear and tear. Since this sail is manufactured from yarn tempered MODEL A MODEL PT-1 Model B Model PT-2 PT-3 Dacron, problems can arise due to 3/32 1/8 5/32 mishandling. 3/16 7/32 1/4 9/32 5 6 10 11 10 9 15 13 SPINNAKER 15 12 14 18 15 The spinnaker is fairly straightforward. 20 16 16 20 16 18 Be sure to repair all tears and pulled 25 20 19 22 18 20 stitches. Folding the sail when storing is 28 23 21 24 19 22 30 22 26 21 24 best. 35 27 25 28 23 25 38 30 28 30 25 27 25 Racing Clinics 40 33 30 32 27 29 27 42 33 34 29 31 29 This tuning guide only begins to cover all 44 36 33 31 45 38 36 33 6 there is to know about racing the J/24. 46 39 37 36 7 The J/24 team at North One Design has 47 40 37 9 prepared a professional, in depth J/24 10 racing clinic that you and your fleet will 11 12 be interested in learning more about. In 14 the of an evening or weekend you 16 will learn more about racing your J/24 18 than you could possibly learn in a season 20 of racing on your own. 25

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.

We would like to thank Harken Yacht Fittings for their help with the deck layout, which they prepared for us.

Good Sailing! 7

J/24 Tuning Guide Rev. R05 NORTH SAILS ONE DESIGN QUALITY CONTROL CHECK

MAINSAIL JIB Corners Corners Cunningham Battens Tack Slug Cunningham Leech Cord Tell tales Royalty Leech telltales Numbers Leech line Country Code Royalty (stitched on) Battens Measurement sticker at head Leech Tell tales 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

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J/24 Tuning Guide Rev. R05