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The J 105

The J/105 was one of the first in what has become the "Sport Boat" phenomena. It represents a breakthrough in the development of dual purpose boats. Short handed ease of handling in a high performance package are the trademarks of the pioneer J sport boat line that has blossomed to include a full range of models. The J/105 is designed to be equally at ease daysailing with a couple, or raced by a crew of five.

The strength of the J/105 lies in simplicity of operation and the tight class rules. While competitive when sailing handicap, there is nothing like the tight mark roundings and overlapped finishes of class racing. Class limitations on sail inventory make the boat simple to sail, fun, and affordable, but present a challenge to the sail design team. Each of the three sails has to cover the whole spectrum of conditions and be durable enough to last longer than the average racing sail. In many ways, this is a tougher problem than creating the multi-sail inventory of the typical handicap racer. The Quantum Sail Design Group has been a part of the success of the J/105 since its debut. From Annapolis to San Francisco, Quantum staff members have sailed countless hours developing and refining the sail shapes and constructions that meet these criteria.

Whether you are looking to finish first or merely beat a rain cloud back to your dock, this tuning guide will help you get the most from your J/105. As with all tuning guides, is just that, a guide. This information should not be taken as absolute. It is impossible to sail strictly by the numbers. Trim and tune are dynamic, requiring constant changes to get the most from your boat. It is more important to understand the concepts behind tuning, and the effects of the different controls so you can learn how to shift gears. Keep an open mind and experiment in changing conditions to determine the right combination for that moment, or simply what works for your sailing style. There is no one way to make your boat go fast. We ask that you keep in touch and let us know what is working for you on your boat, and please do not hesitate to call any Quantum loft if you have questions. the J/105 is a great boat that will provide countless hours of sailing pleasure. We hope this guide adds to your enjoyment.




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1. Rig Tune and Basic Set Up

Basic Set Up: There are three goals:

· Set headstay to maximum length · Center the masthead in the middle of the boat and insure that the mast is in column athwartships. · Set the correct amount of pre-bend and headstay tension for the conditions.

Headstay tension and mastbend are the key variables in adapting the rig setup to conditions. As with all fractional rigs with slightly swept back spreaders, headstay tension is directly related to shroud tension. Windier conditions require a tighter overall setup with less pre-bend. In less breeze the goal is to increase headstay sag with a looser rig and more pre-bend. Setup for moderate to windy days calls for a fairly tight rig and very little prebend. If the mast is set up with too much pre-bend the main will "invert" (get too flat and turn inside out as indicated by diagonal wrinkles running from clew to mid-mast) prematurely as you add backstay. Conversely, in light air sail with less overall rig tension and more pre-bend. If there is not enough pre-bend, the mainsail will be too round and "knuckled" in the forward sections. In all conditions sail with maximum class rake.

A good way to think of shroud tension is that in addition to their job in keeping the mast in column side to side, the uppers also help control headstay tension, and the lowers act like checkstays and control mastbend. With this in mind, the following will provide a sound starting point.

1. Mast Rake: Class Rules allow for a maximum headstay length of 13m (42 ft. 8 in). This is a critical dimension. The boat should be set up within an inch of this measurement. Measure from Center Line (CL) of the pin that attaches the headstay to the mast, to the CL of the pin that secures the headstay to the stem fitting. Position: 2. Mast Step Position Before tensioning the rig, position the mast step plate almost all the way forward in the grooves. Check by measuring from the aft edge of the mast to the bulkhead just aft of the mast. This dimension should be between .237-.250m (9 1/2-10 inches). Putting the mast step forward sets the pre-bend and maximizes rake.

3. Center the Mast:

Hoist a steel tape measure up on a centerline genoa halyard. Pull the tape measure to

an equidistant mark on both chainplates. Adjust the upper shrouds until both measurements are within 1015mm (1/4-1/2"). Both shrouds should be approximately hand tight. With the mast head centered, tighten the intermediates then the lowers approximately hand tight. Site up the aft face of the mast as tension is added, bringing the bottom sections in column with the top.

4.Partner 4.Par tner Blocks:

Position fore and aft blocks so that the mast is pushed to the back of the partners. Check by

confirming maximum "J" dimension of 13 ft. 6 in. This measurement is taken from the front of the mast to the CL of the pin attaching the headstay at the stem fitting.

Checking the mast for centering. Measure to equidistant points on the toe rail. Use mainsail or centerline jib halyard. Measure to insure mast centered in partners. (diagram courtesy of Sailing World)

Tension: 5. Shroud Tension:

(V-1' -1's): a. Upper Shrouds (V-1's):

Hand tight plus 10-13 turns

Intermediate (D-2's): b. Inter mediate Shrouds (D-2's): Hand tight plus 8-9 turns. (D-1's): c. Lower Shrouds (D-1's): Hand tight plus 2 turns.

Dockside tune should now be checked sailing upwind in at least 10 knots true. Adjust shroud tension to get the mast straight. Each shroud (V-1, D-1, D-2) controls the mast section where it is attached. Ease tension if the section pulls to weather, tighten if it falls off to leeward.

Tension 6. Rig Tension For Conditions: In order to increase headstay sag and pre-bend in light air, and decrease in heavy air, use the following table as a guide:

True Wind Speed

0-8 knots 8-12 knots 12-17 knots 17-25 knots

Lower Shrouds

ease 3 turns Base Setting tighten 2 1/2 turns tighten 2 1/2 turns

Upper Sh

ease 1 1/2 Base Se Base Se tighten 2

For optimum performance in conditions over 15 knots true, the headstay can be shortened from class maximum of 13m (42' 8") to 12.95m (42' 6") as well. This is a bit tricky, since the harken drum has to be removed to get at the turnbuckle.

Changes are made for two reasons. First, as noted in the introduction, the governing principle in tuning the J/ 105 mast is that shroud tension controls headstay tension. The tighter the V1's, (and to some extent the overall rig) the tighter the headstay gets because the shrouds are aft of the mast and pull back on the headstay. How much headstay sag is desirable? Approximately 5-6" in light air with no backstay on, gradually reducing the amount as the breeze builds until there is as little as possible (3") in 17 knots plus with full backstay tension.

The second involves the relationship between lower shroud tension, backstay tension, and mainsail shape. Backstay tension will vary with wind velocity. If the mainsail is too full for the amount of backstay being used, the lowers are too tight. If they are too loose, the mainsail inverts prematurely. Mainsail shape will dictate final rig tension. If the main inverts too quickly as the backstay is tensioned (characterized by overbend wrinkles running diagonally from clew to the middle of the mast), tighten the lowers. This reduces bend and makes the main fuller. In a breeze you should be able to apply maximum backstay without inverting the main. Conversely, if the mainsail is too full (knuckled and round in forward sections) with maximum backstay, ease the lowers off.

A good gauge for overall tightness relative to "base" tension are the leeward shrouds. They should just begin to go soft in the upper wind range. If they go slack before that, your basic setup is too loose..

2. Upwind Trim: The Jib

Taking any single headsail through the complete sailing range is difficult, since no one shape is perfect for all conditions. The J 105's non-overlapping, roller furling sail that must weigh a minimum of 6.0oz cloth weight, (and is expected to be reasonably durable), makes this especially challenging, and demands a wide range of trim settings. The Quantum class jib is characterized by a round knuckled entry with a very straight sections aft. The design objective is to make the entry forgiving with a wide steering groove, with a straight back-end to open the slot between main and jib. The hardest part is to get the jib powered up in conditions under 10-12 knots.

entry Knuckled entr y and straight sections aft characterize the Quantum class jib

Four different areas can be readily adjusted, halyard (luff tension), sheet tension, jib-lead placement, and headstay tension.

Tension: Halyard Tension:

In normal conditions use just enough halyard tension to smooth the horizontal wrinkles out of the luff of the sail. More breeze will require more halyard tension. Ease as the breeze drops. It is better to have too little luff tension, particularly in light to moderate conditions, than too much. Leave the jib halyard on the winch for ease of luff adjustment. Mark the halyard itself or place marks on the jib luf f and the furling extrusion as reference. In luff. entry smooth water and light to moderate breeze leave a few wrinkles in the luff. This makes the entr y finer ability, helping your pointing ability, and allows fabric to slide back rounding up and powering up the back of the luff entry sail. In more breeze and choppy water additional luf f tension will round up the entr y making the steering wider. forward, effectively groove wider. It will also flatten the exit as it pulls the shape for ward, ef fectively depowering the sail. Use luff a little extra luf f tension in the upper range of any headsail.

* 0 to 6 knots * 7 to 10 knots * 11-15 knots * 16-20 knots * 20+ knots

Wrinkles (light air mark) some wrinkles Smooth luff (median mark) Firm (heavy air mark) Tight- flat leech, round entry

Use just enough halyard tension to smooth the horizontal wrinkles out of the luff. Leave the beginning of wrinkles in light to moderate air and smooth water.

Tension Jib Sheet Tension

The jib sheet is the most important headsail control and must be played constantly, easing to accelerate, trimming to point. Sheet tension will change with every change in breeze velocity, but the basic premise is to trim as hard as possible without slowing the boat down. Speed first, then point! As the breeze builds over 10 knots, the headsail trimmer should move to weather, bringing the jib sheet with them. Adjustments are not as frequent in steadier breeze, but the trimmer can ease for lump or when a duck in necessary, then use the weather winch to trim in. The best indicator of sheet tension is the location of the leech of the sail with relation to the spreader tip. Put a set of three marks measured from the tip of the spreader: 2, 6 and 9 inches inboard from the tip. We have found the following combinations to be fast:

* 0 to 6 knots * 7-10 knots * 11-15 knots * 16-20 knots * 20+ knots

2 inches off spreader tip 2 inches inside spreader tip 6 inches inside spreader tip 9 inches inside spreader tip** at spreader tip**

** Seaway conditions affect trim positions. Sails can be sheeted tighter in smooth water, but must be eased for lump and heavy-air waves. Remember it is critical to get the boat moving through the water before trying to point! Think of the jib sheet in terms of how it relates to speed. If you are fast, sheet harder, if you are slow, ease slightly.

jibsheet eased

jibsheet trimmed hard

Remember that small changes in sheet tension make big changes to the sail because it's small size and low clew postion. It can only be eased three or four inches before the whole top twists off, so be careful not to get too carried away. Be aggressive but keep the total amount of movement small.

Jib Lead

The median jib lead can be established by measuring from the back of the chainplate to a position on the track 9 inches aft of the chainplate. Set your jib fairlead car with the plunger of the jib lead at this position. This is the median setting (11 to 15 knots). As starting points, try the following settings in other conditions: * 0 to 6 knots * 7 to 10 knots * 11 to 15 knots * 16 to 20 knots * over 20 knots 3 holes forward of median 1 hole forward of median median hole 1 to 2 holes aft of median move aft as required to depower sail**

Median Jib Lead

The median car lead should apply equal tension to the leech and foot of the jib. Moving the lead forward in lighter air, closes the head of the sail and makes the foot more round. When the lead is aft of the median position the foot of the jib will be straight and flat, and the head of the sail will open and twist. Essentially, as the sail is sheeted harder, the lead will move aft, as the sheet is eased the lead will need to be moved forward. If the boat is overpowered continue to move the lead aft or begin easing the jib sheet a few inches to open the leech. If your jib is trimmed so that the whole sail is working, but the mainsail has to be flogged to keep the boat on its feet, ease the jib. Give away the top of the sail to balance the boat allowing both sails to do some luffing.

Tension: Headstay Tension:

Pulling the backstay on not only flattens the mainsail but tightens the headstay as well. In light conditions you will need as much headstay sag as possible to make the jib fuller. In heavy conditions tightening the headstay will depower the jib and help pointing ability. Gradually add backstay tension as the breeze increases. Let the backstay off when you need power. Use a marked batten taped to the backstay cylinder, and a corresponding mark on the backstay as a reference.

The key is to have enough travel in the backstay adjustment to be able to induce up to 6 inches of headstay sag in light air, yet be able to tighten and reduce sag to as little as 1 inch. When the backstay is maxed out the headstay should have 1-2 inches of sag in 15 knots of wind. If you can't get the enough headstay sag with the backstay eased completely off, then the rig is probable too tight. Too much sag with maximum backstay, the rig needs to be tighter.

3. Upwind Trim: The Mainsail

The J/105's large mainsail is more easily adaptable to changing conditions than the jib. This section will address adjustments to halyard, sheet, backstay, outhaul, traveler, cunnigham, and vang. Mainsail trim has two primary goals. First, balancing speed versus pointing by controlling the twist, or how open the leech of the mainsail is. Second, keeping the right amount of overall power, helping maintain a constant angle of heel and right amount of weather helm (more than 5 degrees of rudder is too much). The helmsperson and main trimmer have to work as a tightly knit team, feeling together when the boat is heeling too much or too little, slowing down or speeding up and making the appropriate changes to trim and steering strategy. In many ways, the mainsail trimmer is steering the boat.


Like the jib sheet, there is no one magic position for the mainsheet. It should be adjusted with each change in wind velocity and/or wave pattern. The game works like this. Increasing mainsheet tension reduces twist and tightens the leech of the sail which makes the boat point, but which slows it down. Easing the sheet induces twist, opening the leech, which accelerates air flow across the sail. This allows the boat to bear away and accelerate.

Start by sheeting until the top batten is parallel (pointing in the same direction if you look at it from behind) to the boom. At this point the top telltale will be just on the verge of stall, but it should be flying at least half the time. Once the boat is up to speed trim the sheet until the effect of sheeting begins to slow the boat. Remember, your goal is to get the boat up to speed first, then work on pointing. The mainsail trimmer has to find the delicate balance between speed and point for a given moment, always trying to trim as hard as possible without giving away too much speed.

In light air the sail will be eased and twisted from the median position to get the boat moving. In moderate air the sail will be sheeted firmly with the top batten at least parallel, maybe even slightly tighter. In breeze the sail should be sheeted as hard as the angle of heel will allow, and still keep the boat on its feet. All these positions are tempered with sea conditions. More twist is required in choppy conditions to keep up speed waves.

Median mainheet tension, top batten slightly open.

Maximum mainsheet, tight leech, batten pointed to weather. (Also too "knuckled forward indicating lowers are too tight).

slow, The first thing to do if the boat is slow, or seems "bound up" is to ease the mainsheet! Allow the driver to off bear of f and "press" (sail with them streaming straight aft) on the telltales to get back up to speed. The boat starts must go fast before it can point. Once up to speed keep sheeting the main until speed star ts to drop.


The traveler serves two functions. It controls the boom's position relative to the centerline of the boat, and it steers the boat by controlling helm and angle of heel in the puffs and lulls.

To position the boom, set the twist with the mainsheet then use the traveler to put the boom on the centerline for maximum power and pointing. It is the position of the boom, not the traveler car, that counts. For example when the mainsheet is well eased in light air to promote acceleration, the traveler car will need to be well to weather to keep the boom on centerline. Assuming an appropriate amount of twist, nominal positions for the traveler car will be:

* Light air- middle of the weather cockpit seat * Medium air- centered with sail sheeted on * Over 15 knots- down to leeward cockpit seat * Over 18 knots- centerline to leeward end with mainsheet eased for twist

The boom is kept on center for maximum power. To control helm and heeling, the traveler must be played aggressively as the boat gets overpowered. Down in the puffs, up in lulls. In light air, the traveler will be pulled well up an not move much. In moderate conditions, small rapid adjustments will be necessary to control helm balance. Some backwinding will be seen in the front of the main as the traveler is eased in the puffs. It is important to dump the traveler quickly as a puff hits the boat so that it does not heel too far, but equally important to pull the traveler back up as the power of the puff dissipates. Wait too long and you have missed the opportunity to point once heel is controlled and the boat has acclerated. At about 16 knots true and above, the traveler alone may not be enough to keep the boat on it's feet. At this point, the mainsheet may need to be eased, particularly in big, sudden blasts.

The traveler is the "tip meter" once the sheet is set for twist. The trimmer adjusts the traveler with ever y change in the amount of heel, or any time the mainsheet is adjusted.


Backstay tension does two things. First, as the mast bends, the upper two-thirds of the mainsail flattens out and the leech opens up, depowering the main. Second, the headstay gets tighter which flattens the jib. Both of these depowering effects will keep the boat on its feet when there is too much helm. The goal is to sail the J/105 with as little helm, as the helmsperson can live with, and still keep the boat in a groove. The backstay shsould have a scale of markings (a numbered scale on a piece of batten taped onto the cylinder) for reference Initial settings will be no

backstay in light air, half on in the 11-14 knot range, 90% on in 15 -18 knot range, and maximum (cylinder bottomed out) above 20 knots.

Adjusting the backstay has a large and immediate effect on mainsail leech and luff tension. Bending the mast opens the leech, so add mainsheet as backstay is added, and ease mainsheet as backstay is eased. Mastbend also reduces luff tension, so cunningham is needed as backstay pressure is increased and vice versa.

Luff Tension Luf f Tension (Main Halyard and Cunnigham)

Halyard and cunnigham both tension the luff. Initial luff tension should just smooth out the wrinkles in the front of the sail. Leave a few wrinkles in the lower section in light to moderate air. As the breeze increases more luff tension is required to keep the sail's shape from moving aft. Use the halyard first. When the sail is at the black band, use the cunningham. Remember the effect of mastbend on luff tension sited above.

Outhaul: The outhaul controls the depth in the lower third of the mainsail. Easing the outhaul adds depth and power, pulling it on flattens and depowers. If the helmsperson needs more helm and feel, ease the outhaul. Power in the bottom of the main will increase weather helm. The outhaul is only eased completely when sailing off the wind. In light air, the clew of the main should be 3 to 4 inches from the black band. Pull the clew to the band in 12+ knots of wind. When the crew is fully hiked the outhaul should be maxed out.

Vang: Boom Vang: The vang is primarily an off the wind control. It takes over the job of pulling down and providing leech tension when the boom is eased out and the mainsheet no longer controls twist. However, upwind in heavy air the vang should be used to help out the mainsheet with the job of pulling down on the boom and maintaining leech tension. If the vang is on hard the mainsheet can be eased rapidly in big puffs without giving away the whole leech. This technique is called "vang sheeting", and can be very effective. Conversely, In light air make sure the vang is off, using only enough tension to stop the boom from bouncing.

In heavy air it may be necessary to ease the vang at the weather mark to allow the boat to bear away. Easing the mainsheet may not be enough.

Weight Crew Weight and Steering Upwind

Sail with a constant angle of heel, and with as little weather helm as the driver can stand. This means sailing as flat as possible. Crew weight helps control the heel that controls the amount of helm. The helmsperson needs helm for feel, and to help him keep the boat in the groove (both telltales streaming). Create heel to add, flatten the boat to reduce helm. In light air, the weight should be forward and to leeward to induce heel and helm. If light and lumpy it is especially effective to send all but the primary trimmer below to stack up over the keel. This may seem cruel and unusual punishment, but in most cases it is more comfortable than crouching on the leeward rail staring into the headsail! As the breeze builds, crew should be up and aft, and in fresh breeze they should stack up tightly from the helmsman forward (no one aft of the helmsman). If the boat is pounding upwind, shift a body forward to get the bow Shift weight aggressively moderate (8-12), the and maximum weight to automatically to lulls, stand up, hiking hard as prompt this movement down into the water. in the transition between light and zone between full weight to leeward weather. The crew should respond leaning in when they feel the boat the boat heels in a puff. The driver can based on the amount of helm needed.

In general, it is better telltales streaming

to press on the jib a little, (keep the straight back) footing more than through the water is required to underwater under water foils.

feathering, as speed generate lift from the

Light air setup: crew forward and to leeward (or below), sheets eased, sails powered, backstay off, outhaul eased, lead forward, traveler up.

4. Downwind Trim

Basic Setup:

Most J/105 sailors prefer to set out of the forward hatch. This eliminates the need for a turtle bag. Simply leave the sail flaked on the V-berth under the hatch. When setting up the spinnaker, tie both sheets on the clew, making sure they are outside everything and over the lifelines. Knots are better than snap shackles, which can come unhooked, add weight to the clew, and often get hung up during jibes. Make sure the halyard has a snap shackle with a swivel to help prevent twists. We recommend jibing inside in all conditions except for very windy days when it is easier to jibe outside. Set up for inside or outside jibes when you tie the tack line onto the sail. For inside jibes make sure that the tack line is led over the lazy sheet, for outside jibes lead the tack line under the lazy sheet. When jibing outside the danger is keeping enough tension on the new sheet so it doesn't drop under the pole. If you plan on outside jibes attach a 12 inch piece of batten to the end of the pole to keep the lazy sheet from dropping under the pole.


Before reaching the windward mark launch the pole to the preset mark, and sneak as much of the tack toward the end of the pole as the conditions allow. The bowperson opens the forward hatch and feeds the spinnaker over the bow pulpit. Rounding the mark the bowperson jumps the spinnaker halyard at the mast. Once the spinnaker is up furl the jib as quickly as possible to help fill the spinnaker. Do not trim the sheet until the sail is all the way up.

Trim: Initial Trim:

The asymmetrical requires higher sailing angles, especially in light air. As the wind speed goes up, the boat will accelerate, dragging the apparent wind forward. This will enable you to bear off. As the wind speed drops, you will have to head up. The idea is to keep a constant amount of pressure in the sail, too little head up, too much bear off. on broad reaches and runs sail as deep as the pressure in the sail will allow. The game is to sail with the right amount of pressure for the conditions. When racing one design, performance relative to other boats will help you determine wether you are sailing too low or too high for the amount of breeze. A sound rule of thumb (unless you are surfing down waves) would be to try and sail deeper than your competitors. Still, remember to build speed first before trying to bear off. The spinnaker sheet should constantly be eased until a curl of one or two panels shows in the luff. Overtrimming is the most common problem.


In theory, jibing the asymmetrical is easy! There are two keys to a smooth jibe with the asymmetrical, turning the boat smoothly and continuously through the jibe, and "tractoring" (feeding) the new sheet around the boat quickly, pulling down as it begins to load up on the new jibe. At the start of the jibe be sure the tack line is all the way down, (this keeps the luff tight and helps avoid wraps). There must be good pressure in the sail at the initiation of the turn. Without pressure the sail cannot be eased as the boat bears off. If the helmsman turns faster than the sail can be eased out it will blow through the foretriangle. The clew of the sail has to get to the headstay before the helmsperson turns far enough to bring the mainsail across. Sometimes a very small hesitation in the turn just as the sail is coming across helps.

The release of the old sheet is key. Ease as quickly as possible as the boat bears off into the jibe. It is important that the sheet runs freely through the jibe and the trimmer should stay with the released sheet to make sure it runs. The bowperson is responsible for pulling hand over hand on the new sheet to help the sail around the headstay as the trimmer pull from the cockpit. As the sail comes onto the new side, the bowperson pulls down on the leech to help if fill faster. As the spinnaker fills on the new jibe the trimmer will probably have to ease the sheet significantly to get the sail to the proper trim setting.

turn turn The key to a good jibe is the rate of tur n and the ease and release of the old sheet. The helmsperson can tur n no faster than the sheet is eased.


Weather drops are preferred as it is easier to gather and keep the spinnaker out of the water. A separate line attached to the tack or the middle of the foot of the sail can be used as a dousing retreival line. Just before the drop, unfurl the headsail and have the helmsman bear off to a dead run to collapse the spinnaker. The driver needs to setup their approach with this last bear off in mind. Blow (ease completely and make sure it runs) the spinnaker sheet as the bowman pulls on the retrieval line and gathers the spinnaker into the forward hatch. In light to moderate winds it is easier to pull on the weather sheet and gather the spinnaker from the clew instead of the tack. Once the spinnaker is on deck the halyard should be released and the sail stuffed through the forward hatch.

If forced to do a leeward drop, (in light air or when on a tight reach) the best technique is to grab the foot as the helmsman bears off to collapse the spinnaker. Bearing off hard just at the drop is still the key. Release the halyard all at once until at least half of the halyard is blown but keep an eye on the sail. Make sure it is being gathered as fast as the halyard is lowere. Ease the tack line as you gather the spinnaker under the jib.

Tips Trim Tips Running:

As a relatively small, all-purpose design the class 77 square meter spinnaker requires special trim technique to run and reach at broad angles. The key to running effectively is to project as much area to weather of the headstay and away from the mainsail as possible. Easing the tack line as much as four feet and the halyard up to one foot will help rotate the spinnaker away from behind the mainsail. The tack line begins to angle to weather if the spinnaker is rotating to weather. When eased so that the sail is around the headstay, pull the twing down to close the leech of the spinnaker and avoid letting the top twist off and luff.

Spinnaker tack eased two feet, halyard off one foot to project maximum area to weather.

Tips: Reaching Tips:

The key to power reaching is to keep the boat on its feet. Set up the spinnaker with the tack line all the way down, and the halyard all the way up. Make sure the twings (if used) are off. Get the crew to weather in the normal hiking position. Be sure the mainsheet and the vang controls are attended. If the breeze is up to a point that a grinder will have to tend the sheet, send your smallest person to leeward to act as grinder for the trimmer.

In puffs, the helmsman should bear off too keep the boat in control and on its feet. Head up in the lulls. Ease both mainsail and spinnaker sheets in the puffs. If the boat loads up and begins to become overpowered ease whatever amount is necessary to keep the boat upright. It is okay to luff the main in a puff. Ease the vang if you are about to lose it. In waves, again as the boat loads up, or begins to bury the bow in a wave, the spinnaker trimmer can pop the bow free and unload the boat by easing the sheet out 6 inches to a foot. As soon as the boat is freed up, continue normal trim, working constantly with the steering pattern the helmsman has established.

Don't Forget the Mainsail!

Keep the mainsail working. Power up by easing the backstay, outhaul and cunnigham unless you are overpowered on a tight reach. Use the vang to keep the leech tensioned and the top telltales flying. Above all, make sure the sheet is eased far enough. If the sail does not luff, let it out. It is okay to have the sail against the rig. Letting the rig go forward is also helpful.

Weight Crew Weight Downwind

The crew should be well forward (by the shrouds) and to leeward in lighter air, gradually moving back and to weather as the wind builds. Heel slightly to weather in breezier conditions (12-22 knots) to help project the spinnaker to weather and allow the boat to drive off in the puffs. Weight should be shifted to stabilize the boat and promote surfing in heavy air

5. Miscellaneous Tips / Boat Preparation / Race Day Routine

1. Keep weight to a minimum! Check to assure all storage areas and water tanks are empty. Try to carry only enough fuel to get to and from the race course with a margin of safety. Try to encourage crew to bring only what they intend to wear, limit sea bag weight, and stow crew bags in the middle of the salon on floor against the bulkhead.

2. In some areas cushions may be removed. Other areas, stow V-Berth cushions aft and as low as they can be stowed and remain dry and free from tangling in working lines dropped down hatchway.

3. Remove the dodger if local rules allow.

4. Be sure your bottom is clean. Even newly painted bottoms develop a "scum" within a day or two. Try to have your bottom scrubbed as close to race day as is possible - bribe your diver if necessary. It is a felony to use Quantum Sails with a dirty bottom!

5. Try to sail with as close to maximum crew weight as possible.

6. Install all class legal sail handling aids.

A. Mainsheet fine tune system B. Install U-bolts amidships for twing fairleads, outboard jib lead, etc. C. Fabricate a simple spinnaker twing system which can be led to a cam cleat located near house for easy access. D. Install functional cunningham system

7. Put a visible mark on the bow sprit control line indicating the pole is at full extension. Tie a knot in the control line at the point the pole is fully retracted to act as a stop.

8. Mark the spinnaker tack line at the position that secures the tack to the very end of the pole. Place several additional marks in one foot increments up to four or five feet.

9. Mark the spinnaker halyard at the full hoist position. Add two additional marks at one foot increments down to two feet from full hoist.

10. Mark the deck on the inside of the jib track so car positioms for light, medium and heavy air are easily located.

11. Mark main halyard with maximum hoist settings.

12. Mark mainsail outhaul control line at maximum upwind and downwind positions.

13. Tie the bitter end of the mainsheet (the stainless binnacle guard on wheel boats works well) to something to keep it from kinking and knotting.

14. Tie traveler line ends to stanchion base on each side of boat for easy location and to keep from kinking and knotting,

15. Check the battens in the mainsail to insure they are inserted and tensioned properly before raising the main.

16. Check and lubricate all shackles and fittings on the way to the race course.

17. Check running rigging for chafe while rigging the boat.

18. If possible the keel and rudder should be faired to templates. This is a lot of work, but ultimately is well worth effor fort. wor th the ef for t. At a minimum the bottom should have a hard, sprayed on paint sanded to 600 grit or burnished. bur nished.

19. Practice! Better yet, arrange to go out with another J/105 for some straight line sailing.

6. Sail Care and Maintenance

· The class jib must be used on the furler, but leaving the sail furled for extended periods is hard on it, especially the roller battens. UV degradation is the most damaging element the sails will experience. It is important to cover sails when not in use. We recommend that a luff sock be used over the furled jib in place of a UV cover.

· To avoid mildew, dry sails thoroughly whenever possible before putting them away for any length of time. Leave your spinnaker spread out below rather than stuffed in the bag.

· Tape over sharp objects on the rig, stanchions, etc. If using a genoa, tape the spreader tips with plastic tape rather than leather or the rubber rig wrap. Rollers at the front stanchion help the sail over the stanchion when trimming in.

· Release the tension on the corners of the sails when not in use. Slack the halyard slightly on the jib if left on the furler. Ease the outhaul on the mainsail before covering it. Slack leech lines slightly if you have been using a lot of tension.


Rolling is not critical, but it is probably better for the sails over long periods.

· When storing for extended periods roll mainsail and jib carefully. Remove battens from both sails. Fold your spinnaker; stuffing is hard on the finish. Store sails in a dry, temperate area.

· Clean salt and dirt at least annually. You can bring them to your local loft for this service, or do it yourself. Scrub with a soft brush and a mild detergent. Avoid harsh chemicals or detergents, as they will break down the finish. Spots will fade with cleaning, time and sun. If mildew occurs, this first step is to kill the mildew. If detergent doesn't do the job, mildew removers like Lysol work well. Avoid mildew products that include bleach as their cleaning agent. Dry sails thoroughly before storing.

· Schedule an annual appointment on the water so we can photograph your sails and catalogue the changes. Periodic adjustments to the leech and to adjust draft depth and location can extend the shape life.

The J 105 Guide to Tuning and Trim is published by the Quantum Sail Design Group Corporate Offices 951 Bay Ridge Road Annapolis, MD 21403 All rights reserved. Compiled by Norman Davant, Seadon Wijsen, and Hogan Beattie from Quantum Pacific Reproduction by any means is encouraged. The power of knowledge lies in the sharing



J 105 Tuning Guide

21 pages

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