Upwind sail tuning made simple
(if not necessarily easy)
by Uncle Al (W3854)
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Introduction: This was meant to be a short, little blurb written for some guys on the CL Users Forum who, in the topic Magic Box, got into the confusing complexity of tuning options. Man, I thought, it's a whole lot simpler than that on our boat:
And Bob is indeed your Uncle! It is, in essence, that simple. But as you will note, it's the rationale that takes up space. And then, of course, I decided it needed illustrations. So now we've ended up with this. I do hope you find it useful.
Best wishes for happy sailing,
Uncle Al (W3854)
Keeping things in perspective. Rigging - both standing and running - exists only to be the servant of your motor, the sails. So, when you see/hear tuning numbers, always keep in mind that these are meant as a means to an end rather than a goal in themselves. On a racing sailboat, be it a dinghy (my area of expertise) or a keelboat (a black hole in my knowledge), our real and only goal when it comes to tuning is to keep the sails up and properly set to take best advantage of the wind....
Sails - general principles. Like the wings of a very slow-moving airplane, your sails are curved fore and aft, so that air flowing over them generates lift towards the outside of the curve (below).
Your sailmaker builds a certain amount of smooth curve into each sail. The depth of this curve will vary somewhat from class to class and from sailmaker to sailmaker, and on our boat, is something that we no longer worry about trying to influence except insofar as we use vang tension to bend the mast and thus flatten the mainsail when we are overpowered.
The designed fore-and-aft position of the area of maximum draft depth in sails is usually from 40 to 50% aft from the luff (above). Various factors affect the maximum draft location, but for basic tuning you can ignore this except as specifically addressed later in this guide. Note my attempt at diagramming below where I try to show various places the max. draft can end up to due to rig settings and/or wind friction.
In essence, all you need to do is try not to screw up the intended shape more than necessary. How do you get and maintain the optimum shape in your sails? Mostly you will do this by adjusting - in very simple ways - their leading and trailing edges, i.e. the luff and the leech. Details to follow in a moment.
Getting underway: Before we sheet in and start sailing, we will ensure that our sails are properly hoisted. This may seem obvious but when I look at other boats sailing around me on any given day, some review appears called for. After all, we have to give our sails a chance to perform correctly. A guitar player may well do all the pickin' and grinnin' to perfection, but if (s)he starts with strings wrongly tensioned, it's not much good.
First, we need to ensure that each sail is hoisted fully, to the extent that there is no excessive slack in the luff of either sail. We must however, be equally careful not get carried away: we must not stretch the luff, either, as this will put too much fullness into the leading edge of your sail, especially in light air. On SHADES, we actually always hoist our jib first, but here, the layout necessities require me to begin with ...
the main: Hoist the main to the limit band at the mast top, and then pop the boom back onto the gooseneck. If you now see stretch bulges in the luffof the main along the mast (like what you see if you stretch a piece of cloth,or in the photo on the right where Three Gawthrop has not yet eased his main cunningham after that last windy beat), raise the gooseneck or back off the main halyard until any sign of such stretch disappears.
Usually, there are small wrinkles where the luff bolt rope sleeve meets the sail cloth. Those wrinkles that Marc is admiring above, "speed wrinkles" in Wayfarer talk, need to be left in, at least when you're deciding how high to hoist the main. If they have been smoothed out, your luff is too tight (even though it may look nicer unwrinkled!)
In the photo below, Jim and Alice, have stretched their luff with a main cunningham, which is fine for the upwind work they've just finished doing in a breeze (to be discussed later), but your main should never have a stretched luff like this that comes from simply pulling too hard on your main halyard when you hoist.
The jib is a bit trickier: on our Wayfarer, we have a jib luff wire that runs down a sleeve in the luff and that usually takes over forestay duties once the halyard is tensioned for sailing. The head (top corner) of the jib is lashed to an eye at the top end of this wire.
The bottom of that sleeve used to be lashed to an eye at the bottom end of the luff wire, but it was discovered that, over time, the sail cloth shrank. As a result, the cloth along the luff was being forced to stretch when the luff wire was put under suitable tension, giving stretch bulges (see photo above) along the luff which are seriously detrimental to performance (much of the time).
What most of us do these days to avoid this potential problem, is leave the tack (bottom front corner) of the jib loose (above), i.e. not lashed on to the wire eye. For us, there is thus a very definite distinction between jib halyard tension and cloth tension in the leading edge of the sail. And most of the time, the luff cloth tension is virtually nil!! To keep the cloth from riding up excessively, we use a grommet (above) in the tack of the sail through which we run or tie a thin line (above).
That line (speckled white above) is called the jib cunningham. As you can see here, we have the line dead-ended at deck level. Then it comes up through the tack grommet, down to a mini-block, and back to a cleat on the deck beside the mast.
Again, do not tension this except to remove the worst of the wrinkles from the luff - but do keep some speed wrinkles (above).
Often, my crew, Marc, and I take turns helming our Wayfarer in alternate races of regattas. When he helms, he has me ease the jib cunningham in lighter winds until the (fairly stiff) cloth of the luff is a veritable zig-zag as it goes up the luff (see photo above). That is too loose for my taste, but the helm needs to be comfortable, so I don't argue the point - especially since he wins almost every race he helms. Remember the sailor's most useful saying: "When in doubt, let it out!" Ask the sailors at the 2006 PMG Can Am Regatta, and I think they'll tell you that a luff less tensioned helped a lot.
Well, that just about gets us set to sheet in and go - except for a few small bits of review that will explain the logic behind what we are about to do:
Basic assumptions made by your sailmaker:
Your sailmaker assumes that:
1. Your mast does not lean excessively to one side or the other (i.e. stays are of more or less equal length) but that it is leaning slightly aft (raked) such that, with the main and jib properly hoisted, but without any mainsheet tension, your boom hangs more or less level, i.e. parallel to the waterline (above).
2. on a dinghy, your jib luff will sag a certain amount (2 - 3" in a Wayfarer or CL) at mid-luff in any amount of breeze (photos above: front view, then side view). This is because the luff is supported at only two points: the tack and where the halyard enters the mast. Your jib luff is cut to anticipate and match this sag, i.e. you will see a slight concave curve in the luff when you lay the jib flat.
3. Similarly, the assumption is made that, as the wind gets up, the mast on a dinghy will unavoidably bend (2 - 4"/5 - 10 cm or so on a Wayfarer, more if you let it) (above). Your main luff therefore has been cut with extra cloth (convex curve) in the leading edge to match whatever mast bend is normally expected for your type of boat. Your job thereafter, is to keep the mast from bending much more than that, if possible.
Other basics regarding sail shape and function:
The above image has been borrowed from the late Eric Twiname's wonderful 1973 book Start to Win. As I recall, they sprinkled aluminum dust onto water in a test tank with the current (to simulate wind) running from right to left (see arrow). Foils were then inserted to show how the air particles that make up the wind (represented by the aluminum dust floating on the water) flow over a sail. As you can see from my attempt at a diagram below, for a sail to work efficiently, its leading edge must meet the wind head on, i.e. the leading edge of your sail needs to be exactly parallel to the wind, so that the wind can flow easily along both sides of your sail.
If you point too high, your sail starts to luff because the wind is blowing in at an angle from the leeward side of your sail. Worse, if you point too low for your sail set, the sail does not luff but does lose vast amounts of its lift because the wind is blowing in at an angle from the windward side of your sail and thus cannot flow properly over the leeward side which is the side that generates your lift (= power). This is known as stalling out, something that causes planes to crash. (Once more: When in doubt, let it out!)
The groove. The more rounded (amount of fore/aft curve) your sail's entry, the more forgiving your sail will be of less than perfect angling to the wind (be it due to inexperienced helmsmanship or bouncing around in waves or whatever). The amount of this entry curve is directly proportional to the amount of jib luff sag you choose to sail with: more sag = a more rounded (fuller) entry, and vice versa.
On a Wayfarer or CL, the amount of luff sag is directly proportional to and controlled by the amount of jib halyard tension. Thus, the tighter the halyard, the flatter the entry becomes, and vice versa. So, if you ease the jib halyard, your jib luff entry becomes more rounded, and what is called your steering "groove" becomes correspondingly wider (more forgiving of imperfections in angle of your sails to the wind). Thus, an expert helmsman sailing in a very steady wind on flat water can get away with a flatter jib luff entry, i.e. sail with a narrower groove, than a beginner struggling in big waves or very shifty winds.
You may well be asking at this point: "So why not sail with a wide groove all the time?" Well, remember that you have to steer your boat such that the wind meets the jib luff entry head on. So the trade-off is that a more rounded entry (see dotted line above), forces you to sail more off the wind in order to give your sail entry a functional angle to wind, i.e. the lower you will point. Thus, it pays to sail with the flattest jib luff entry you can get away with. But here again, it is a case of when in doubt, let it (your jib halyard) out. If SHADES does not feel right going upwind, the first cure we always try is expanding the "groove" by easing the jib halyard and thus increasing entry curvature. (On a keelboat with the jib hanked on to the forestay, you may well have to ease the jib sheet a bit to make your entry rounder?)...
Note: Keelboat clarification supplied by Andrew Haill to fill the above gap in my knowledge:
----- Original Message -----
From: Andrew Haill
To: Al Schonborn
Sent: Tuesday, March 27, 2007 2:43 AM
Subject: upwind sailing
... "On a keelboat with the jib hanked on to the forestay, you may well have to ease the jib sheet a bit to make your entry rounder?". I'm far from an expert but at least on the keel boats I've sailed, one still uses the halyard to alter genoa shape along the luff, the sheet has a secondary effect on it, but it is mostly halyard tension and the sheet used to determine angle of attack and leech tension albeit with some effect on entry shape. Backstay will tighten up the overall jib sag as well, which is fortunate because when you want backstay to flatten the main as the wind builds, you usually also want to reduce the headsail sag. It is still the halyard tension however, that really affects how round the entry is and how hard it is to go upwind in the groove. Every control on a boat seems to have one main purpose and at least one secondary effect, but that's half the challenge cause it would be pretty boring if there was just one go-fast rope to pull.
Next, we'll talk details about the inexpensive "instrumentation" that will easily tell you if your entry is too flat.
Setting the groove for upwind work in the day's conditions:
Let us assume a nice medium breeze of 5 to 8 knots. To set up for existing conditions on our Wayfarer, we deliberately crank up jib halyard tension more than we expect current wind strength to support, i.e. until we reach a point where we think we'll have less jib luff sag than our sailmaker anticipated. This in turn will make our entry curve too flat, and the steering groove too narrow, for the conditions.
Now comes the acid test: We sheet in and sail closehauled. I'm assuming here, that everyone knows how to sail to the ticklers. Most good racers usually point up until the ticklers on the windward side of the jib angle up 30 to 45° (see Mike McNamara diagram below). This has two benefits: 1. It lets us point that little bit higher (pinch), and 2. it keeps us well away from the dreaded stall.
If the jib luff cloth actually begins to lift (luffing), we know we are too high, but if the leeward ticklers start lifting or, God forbid, going in circles, then we are sailing too low (stalling out).
Identifying a jib luff entry that is too flat: A sure sign (on fairly flat water, anyways) that the entry is too flat due to an overly tensioned jib halyard, is ticklers that are jumpy: from one second to the next they switch from indicating luff to showing stall, sometimes both at once. If this totally unacceptable state of affairs exists, we start easing our jib halyard in small increments to make the entry rounder until the ticklers settle in such that the jumpiness disappears. At that point, we have theoretically got our jib halyard tension (and its attendant entry curve and steering groove) to its optimal setting for the conditions. And, we have set the correct rig tension at the same time, since the jib halyard/luff wire combination is deriving its tension by pulling against the resistance of the shrouds (remembering that on dinghies, the forestay is set loose enough that its function of holding up the mast is taken over by the jib halyard almost as soon as the jib goes up).
If the wind increases, we will add halyard (and rig!!) tension to counteract the increased luff sag caused by the extra wind pressure, and vice versa. Always though, the ticklers are our instruments that will tell us when the entry is too flat. If they start to get twitchy, we ease off some halyard. Alas, there is no direct way to tell if the entry is fuller than it needs to be. To be sure that you have it as flat as you can get away with, you need to overtighten and then ease off as much as is necessary. Eventually, you'll reach a point where you'll pretty much develop a feel for an amount of halyard tension that is "in the ballpark" for existing conditions - a useful skill in mid-race where overtensioning and then easing off as needed, are not an attractive option. There, your best guess is really the only way to go. If the ticklers get antsy, you'll know you've got too much halyard tension and will need to have your crew ease the halyard a bit. That having been said, we often find that even though the tickers do seem to be behaving well, the boat still feels a tad slow. In that case, we are in doubt and so we let it out (the jib halyard). Almost invariably that helps - perhaps only psychologically, or because the boat is just that little bit easier to steer within its expanded groove.
One quick example to show the importance of a comfortable groove: We once sailed a 1992 Wayfarer Worlds qualifier on Lake Ontario in a nasty cross chop of large leftover swells from an overnight SE gale and the new waves from a southerly wind of about 10 knots. By the time we had eased the halyard to give us some semblance of well behaved ticklers, the middle of the jib luff was hanging a good 9 inches to leeward of our slackless forestay - talk about luff sag!!! We pointed lower than all the others who were sailing with tighter halyards but we absolutely axed them on better boat speed (which in turn makes your board more effective so that we didn't even end up losing much distance to windward).
What about the mainsail entry, I hear you ask? Well, luckily for us non-high-performance dinghy sailors, only easily adjustable mast bend would force us to distract ourselves by trying to fit the mast to the main's basic, built-in entry shape. So we can happily ignore that as being immaterial for the moment, since we have no such facility on a Wayfarer or CL. In the early 90's, I actually did figure out a way to pre-bend my Wayfarer mast relatively easily for really light airs, but doing so seemed to make no difference to our performance, so that I now ignore the main entry with no noticeable ill effects. The KISS principle in beautiful action!! Note: We will talk about using the main cunningham at the appropriate time later in this guide.
So, having set the jib entry to our satisfaction and left the main entry unfiddled, we can now turn our attention to the sheets and how to use them to set our sails at the desired angle to the wind....
Sheeting the sails: We do not want only part of our sail set such that its leading edge is angled to meet the wind correctly, as is the case with CL1979's mainsail above. Instead (99.9% or more of the time), we want the whole leading edge to be at the same, optimum angle to the wind all the way up and down the sail, i.e. the entry parallel to the wind so that the air particles can flow along both sides without impediment, the way CL2469 has it on the left above. Fortunately, when the boat is closehauled, such an ideal angle of the whole length of the entry is easily achieved with the sheets (and, when overpowered, the vang) - as you are about to see....
Sheeting the jib: The "and now for something completely different" department. To the best of my knowledge, the following is to be found nowhere else in educational sailing materials. The latter worry about the ideal fore and aft position of your jib sheet fairlead, usually where an imaginary line drawn from the mid-point of your jib luff through the clew grommet meets the deck (or seat). My belief has come to be that such lead location is not crucial and that fiddling with it takes up time that could be better spent on almost anything else.
Here's what happened: While Mike McNamara, several times Wayfarer (and Albacore) World champion, was coaching us in 1990, he had us tip a rigged Wayfarer on its side, and asked one of us to sheet the jib in to closehauled. "Now," said Mike, "watch what happens to the upper leech when I pull the sheet in another inch." Sure enough, the upper jib leech moved inwards 5 to 6 inches along the spreader. Mike's point of course was that small jib sheet tension adjustments have a major effect on the sail when sailing closehauled.
But if that is the case, I then wondered, will it really matter much, where on the track I have my lead? Because upper part of the sail comes in more than the lower when you're closehauled, will there not come a point where the upper and the lower part of the sail are in balance at the same optimum angle to the wind. For example, if the upper jib is twisted off to leeward too much, I can sheet in more. As I do, the upper part of the jib is being brought in more than the lower part, and eventually the excess twist will be removed, and the whole entry will meet the wind at the same angle. And this will happen regardless of the lead's position on its track. Sheeting in from further forward just means that I'll need less tension to reach the balance point because I'm pulling down more directly on the leech and the upper part of the jib. By the same token, moving the lead further aft just means the jib foot will be in pretty tight by the time the upper part of the jib catches up.
For what it's worth (in my experience, nothing), moving the lead forward means you'll be sailing with the foot of your jib progressively fuller (more curved), and vice versa if you move the lead aft.
On W3854, Marc and I have not moved our jib lead position from its position just forward of the thwart on the inside board of the front bench in years, regardless of wind conditions. In 2010, I finally removed all the unneeded jib lead track (see photo above) and there have been no problems with this set-up. As mentioned above, what we do instead of moving the lead is to sheet in until the upper jib luff ticklers show luffing at the same time as the lower ones. If the top ones show luff while the bottom ones are showing perfect sail trim, the top needs to come in. So the crew sheets in a small amount and the top comes in more than the bottom. The helm keeps steering to the bottom ticklers, while the crew checks and keeps adjusting the sheet until the upper and lower ticklers are "in balance". By the same token, if the top ticklers show stall while the bottom ones are showing perfect sail trim, then the sheet needs to be eased slightly. Again, the helm keeps steering to the lower ticklers while the crew works to get the ticklers into balance. Mike McNamara told us his crew basically never cleats the jib upwind since he is constantly working to fine tune this balance. Our experience has been that once we find the balance, it's perfectly fine to cleat the jib there. We then adjust only if there is a significant change in wind velocity. Or, if we don't like our speed, then we are definitely in doubt and hence let it out (a smidgen!) - "it" being both the jib and the main sheet in this case.
Before Mike told us about this upper and lower tickler balance, we were achieving the same thing with a tickler attached to the jib leech near spreader height (see attempted diagram of our ticklers system above). We still use this jib leech tickler in light airs when it is easy to get a look at (i.e. we're not hiking out). The very simple principle here is to sheet in until the leech tickler is on the verge of getting sucked forward behind the jib leech, then ease out half a smidgen. This allows us an easier, more accurate read than trying to compare the degree of luff or stall in the upper and lower ticklers. Both methods do the same job equally well. But the leech tickler is great for telling you exactly when you must not, under pain of death due to slowness, sheet in any further. Again it is better to sheet too loose than too tight. But it is, of course, best of all to sheet in as much as the leech tickler will let you get away with, i.e. to not waste any drive from your upper jib by having it, in effect, luffing a bit.
Afterthought: On a W or CL, it seems to make little difference how far inboard you have your leads. We had ours on the deck for years in the 70's and still did not hurt appreciably for pointing against those who had already moved their leads inboard to the benches. We did ultimately move them inboard which common sense says should let us point just that tiny little bit higher.
Sheeting the main: Little-known fact #2: A boat points on its mainsail leech. I don't know exactly why, but Mike Mac confirms it, and that's good enough for me. This concept is counter-intuitive, but I find it to be most definitely true. The tighter the main leech tension you can get away with, the better distance you'll make to windward. I find that when we sheet the main in a bit harder once we are up to speed, we make better distance to windward relative to boats who do not make this change. Note however, that I said "leech tension you can get away with". Overdoing this is definitely damaging to your performance, as we will look at shortly.
Another basic point - probably related to angle of the leech to the centre line of the boat - is that you never want to move your traveller off to leeward even a few inches (in W's or CL's, at least). That kind of stuff kills pointing and should be reserved for survival conditions of huge waves and howling winds, where pointing has become a relatively low priority.
In Wayfarers, most people avoid this "keeping the traveller centred" problem altogether with a bridle (see photo above). Remembering that being able to get adequate leech tension is crucial to optimal pointing, we must ensure that the bridle is not too long, i.e. we don't want to reach the "block to block" position while useful leech tension can still be added. In so many words, err on the side of having your bridle too short!!
On W3854, we have our bridle set to a length so that we reach the block-to-block position just before we get overpowered and have to start using the vang. In the top photo above, note that we are getting close to being block to block by the time we are both on the windward deck, while in the middle picture, we are sitting out and have sheeted in as much as this bridle will permit (block to block). In the photo immediately above (that's Marc steering and me crewing) we are again sheeted block to block and on the verge of being overpowered. Should the wind increase, it will be vang time, but more of this later.
Bridle bonuses. Besides automatically ensuring that we are always sheeting (virtually) to the centreline of the boat (which is best for pointing), the bridle does two useful things:
1. it allows us to sheet almost to the centreline in lighter winds without the excessive downpull that would hook the leech too far to windward if we tried to get the boom in to a similar position working from the traveller, and
2. it gives us a very easy read on mainsail position, i.e. do we have one inch, two inches, three inches between blocks (above right) which is far easier to see than the difference between say 30, 31 or 32 inches between the block on a traveller and the block on the boom (above left).
So, how do we know when the main is sheeted in just right? Our instrumentation here is also low-tech and inexpensive: one leech tickler near - but not right at - the upper batten (where it has more stitching to get caught on). Perhaps the easiest way to illustrate how we use this tickler is to go through our routine as we sheet back in while coming out of a tack.
On the premise that it is always less damaging to undersheet than to oversheet, especially when we've already slowed due to the tack, we always undersheet both jib and main as we complete our tack. (Note: Such undersheeting is also a desirable buffer against capsizing when you're tacking in a blow!) With luck and good crew/helm teamwork, helm and crew then both sheet in at the same time (which, as a bonus, gives us a nice little nudge when we need it the most). The crew sheets in as outlined under "sheeting the jib" above, although we tend to use easier visual references for short-cuts to start with, like how much of a gap was there between jib foot and V-shaped coaming on the last tack (see series of three bridle pics above), etc. The helm, meanwhile, sheets in until the leech tickler shows signs of wanting to hide to leeward of the leech. Of course, on a normal day, with reasonably consistent winds, I will have observed how big a gap should be left between the blocks to put us into what can well be called first gear, and I can immediately sheet that far in without having to to look up at the main leech tickler. This is especially useful in high-stress racing situations.
Let me give you the gears: When the boat has slowed down for any reason (such as tacking, motor boat or other waves, disturbed air, too much pinching, etc.), it first and foremost needs to get moving again. And sailing with the main leech ticker nicely streaming aft (but on the edge of getting sucked behind the leech) is the sailing equivalent of driving in low gear. When do we shift to a higher gear? Exactly! When the boat has regained good speed for the given wind strength. And how do we gear up? We crank the main in another few inches - how many depends on the type of boat, wave conditions, amount of wind, and so on. It's something that has to be learned by trial and error on any given day. With luck, you'll be near another beating boat against whom you can speed test, so that you can see if cranking the main in a bit more is helping. If it's helping the other guy, go back to first gear, get your speed up, and try cranking the main in a bit less the next time. And so on. I always do a lot of main uncleating, adjusting and then recleating when going upwind. Unless the beat is in exceptionally steady winds, few waves and there is a lack of opponents near by, I adjust the mainsheet dozens of times on a one-mile beat. Like many sailing things, the more time spent in the boat, the better your feel will become. Note that throughout all this, my crew has been dreaming of
What if the main leech tickler refuses to fly? If the tickler is out of order in insufficient wind or because it has gotten stuck due to rain or other causes, a very valid rule of thumb is to sheet in until the top batten is parallel to the centre line of the boat (above)....
Trivia: We usually do very little with our outhaul, upwind or off the wind. Most times, we set it for the day and never touch it again, unless we really have nothing else to do, like on those long two-sail reaches in the Can Am Regatta where we eased the outhaul to power up the foot of the main a bit. (More curve equals more power.) Usually however, adjusting the outhaul represents fiddling time that is better spent watching wind on water, waves, and fellow competitors, or plotting strategy - or even having a beer or telling jokes. For light and heavy winds, we tighten the outhaul to or near the max. In the mid-ranges, we ease it a bit for a fuller lower quarter of the mainsail....
Bringing the wayward draft back into the fold: Especially when you're sailing closehauled, the wind blowing across your sails creates a surprising amount of friction which will blow some of the cloth aft from its designed location of maximum depth - especially on old sails that have gotten soft, but also on brand new sails with stiff cloth.
This was brought home to me most strikingly one spring: Having just read that the main is supposed have its max. depth of draft about 50% aft in the mainsail (40% aft in the jib, I believe), I raised a brand new suit of sails with the boat on the trailer on a calm day, and took "draft" pictures. I was appalled to find that the main's maximum draft was only about 25% aft. Distressed, I phoned my sailmaker, who chuckled and said: "We'll go sailing next time there's a breeze, and you'll see that the wind going across the sail will blow the draft aft right to where it needs to be." Well! Let me tell you. I found this well nigh impossible to believe!! But sure enough, in about 8 knots of breeze a couple of days later, there was the draft, blown from quarter to half-way aft as we sailed closehauled. What a relief!
Pursuing this line of thought further, however, begs the question: "What if the wind starts blowing more than the 8 knots that moved the draft from 25 to 50% aft? Won't the draft move too far aft??" Unless you have mylar or kevlar sails, the answer is yes, and this is where the cunninghams ride to the rescue. The principle involved is that if you stretch one edge of the sail, this stretching pulls more cloth towards that edge. Thus, tensioning the luff moves sailcloth towards the luff, i.e. the draft further forward.
The upshot of all this is that when the breeze gets up enough to push the draft too far aft in the main, we start pulling on some main cunningham (above). This pulls the draft back forward, God willing, into the place half-way aft where it is supposed to be on the main. When we use our 1994 mainsail with its 13 years of hard use behind it, we crank on more cunningham and sooner on the wind scale, since its cloth is tired and blows aft more easily than on our "new" 2003 mainsail.
When we use the jib cunningham to do any luff stretching at all (see photo above), we use it extremely sparingly....
Vang: Upwind, we never use our vang until we can no longer hold the boat down without its assistance. But once we are overpowered, a multi-purchase, easily adjusted vang is worth its weight in gold, especially in gusty conditions where it wants to be eased as soon as we can hold the boat (reasonably) flat without it, and then cranked back on just before the next gust hits. Controls that go to both sides of the boat where either crew or helm can adjust them are well worth the investment of your time and money. See Rig It Right for our system.
When you are overpowered upwind, the vang does two extremely important things: It flattens your main by bending the mast (above), and secondly, but no less important, it keeps absolutely essential tension on your main leech, letting you keep pointing even when you have to rag the main to spill wind and keep the boat reasonably flat.
In the pictures above, notice the leech tension we're getting (right), even from our "blown-out" old main, which in turn is bending the mast - all due to applying lots and lots of vang. On the left, only the upper mainsail is falling off, a sure sign of too little vang, and because Richard and Michele are having to spill some wind, they're getting too little leech tension. This hurts in two ways: pointing will be poor, and the mast is not being bent to flatten (depower) the mainsail.
I have found this out the hard way, by getting axed in a race, when I experimented with ragging the unvanged main, having brilliantly figured out that this would luff the top of the main first and would ease a lot of the heeling forces much sooner. Obviously that had to be faster! Alas, it took less than a single beat and our having plummeted from a great, race-leading start to 9th place, to discover that the reality did not match the theory. It would be another 10 years before Mike Mac would provide me with a reason: the boat points on main leech tension. This is in fact the main reason why Wayfarers have gone to adjustable spreaders. These can be (and are, for a blow) set to help the mast resist being bent, which in turn lets you have more leech tension in the main which has to be pulled down by the vang that much harder before the mast is willing to bend, and presto, better pointing even when the sail is well ragged!
Everything you should know about ticklers (telltales). Ticklers are going to annoy you each time you sail, if you don't make a little effort to get the right kind and to install them the best way.
Materials: I have found that sticking ticklers onto the sail with tape (see lower ticklers in the photo above) is the easiest but not the best way to install them because their loose ends tend to get stuck on the tape at inopportune moments. Also, ticklers made from spinnaker cloth or better yet, your favourite Elvis tape, may be the lightest and most wind sensitive, but they too, are not - in my experience - the best choice. When they get wet (rain or spray), they stick to the sail cloth "forever"!! No, the ideal solution is virgin wool "sewn" into your sail. The virgin wool (of a nice, dark colour so that you can better see the leeward tickler through the sail cloth!) is water resistant due to its oil content and will fly again very soon after a soaking.
Installation: To start with, I get a sailmaker's needle with an eye that will - grudgingly - accept wool's thickness. When I couldn't find my wife's needle threader, I put a loop of thread through the needle's eye, inserted the end of the wool through the thread loop, and then used the thread to pull the wool through the needle eye. This was enough of a pain that I made sure I cut off a length of wool (three or four feet) which was certain to avoid my having to do more threading and to be more than enough to make eight four-inch ticklers (6 for the jib luff, and one each for the main and jib leech - well, if you want to get technical, three luff ticklers @ 8 inches/20 cm, half of that length showing on each side of the sail.)
Jib luff ticklers: We have three "sets" of 4-inch luff ticklers located at approximately quarter, half, and three-quarter height. It is more important to keep these ticklers away from seams that can snag them, than to have them exactly at quarter height, etc. It is important, however, to have all three ticklers the same distance in from the leading edge of the jib (to avoid confusing readings). That distance should be just far enough aft of the luff sleeve stitching to keep tickler ends from being able to snag.
Having marked the desired location for our three luff ticklers on the jib luff's cloth, we now use the needle to thread the first tickler through the cloth such that 4" of loose end remain on one side of the sail. Next, we cut the wool such that there will also be 4" on the other side of the cloth. All that now remains to be done is to tie into the wool an overhand knot (above) close to each side of the cloth to keep our tickler centred with 4" on each side of the sail. Note: Until I used the blunt end of the needle as a fulcrum inside the loop of the overhand knot, I had trouble working the knot as close to the cloth as I would have liked.
Leech ticklers: On our main, we use just one wind tuft (tickler), on the leech near the upper batten. The jib leech tickler also goes at about 3/4 height, far enough above or below the spreader to avoid entanglements as much as is reasonably possible. The leech tickler attachment procedure is as follows:
1. put a figure 8 or overhand knot in the long loose end of the wool.
2. Slide the needle inside the fold of cloth at the trailing edge of the leech between two of the stitch holes, letting the needle come out through the folded cloth at the very aft end of the leech.
3. Pull through until the stopper knot is wedged safely inside the fold where it will not catch the rest of the tickler.
4. Cut wool to leave a tickler of the desired length
Off the wind (and, strictly speaking, off topic): Off the wind, things are a fair bit less complex. As far as your sails are concerned, "tuning" is mostly a matter of letting your sails out to the edge of a luff, to once more avoid the dreaded stall, and of using enough vang to keep the boom level to the water line. In this regard, I will leave you with three pictures:
Pretty as these curves look, none of the above sails are using the wind to best advantage. Using enough vang to get the booms level would leave these mainsails at a far more uniform angle to the wind. As it is here, since neither main is luffing, one must assume that large parts of them are oversheeted and thus stalled. Eek!! (The jibs have the same problem, though to a lesser degree. Really keen crews in close, two-sail races have been known to by-pass the jib lead and hold the sheet further forward where they can add more downpull on the leech and remove this performance-draining twist.) PS: In heavy airs, an unvanged main adds to the danger of capsizing during a gybe because the boat has to be turned much further before the wind can finally get around behind the upper main and slam the main over.
Note how Uncle Al here - to keep the boom from skying - has tightened his vang just before reaching the windward mark after not needing it while going upwind. In another pre-rounding preparation. Marc has just let off both cunninghams completely (see wrinkles in both luffs) because cunningham tension is undesirable on reaches and runs as can be seen in the next photo where ...
... CL1336 has the main nicely vanged to keep the boom level but has a stretch bulge up his jib luff that is most likely due to cunningham effect.