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Old 09-05-2003
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Traveler usage?

I''m a novice sailor with a C320 still trying to learn and improve sail trimming techniques. I''ve been concentrating recently on traveler technique, but have been unsuccessful in gaining desired results consistently. What I''m curious to understand now is under what conditions are average weekend sailors compelled to adjust the traveler? My curiosity was further piqued after I scanned about a dozen sailing mags looking at action photos of many (100+) boats underway - I counted on one hand the number of boats that had their traveler in any other position than centered, in wide ranging weather/sea conditions.

I''ve been experimenting with the traveler adjustments in light winds trying to induce more twist and power-up the mainsail (traveler to windward, ease the mainsheet) - this did not gain me boatspeed. In heavier winds, I''ve had to depower the main by dropping the traveler to leeward - this does work well in gaining better boat control and limiting apparent wind speed.

I understand that I need more trimming practice and to develop a better feel for my specific boat. And I know that I''ll need to master the traveler as I contemplate racing one of these days. So, is it only the anal, sailing perfectionist (or club racer) that spends time on the traveler?
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Old 09-05-2003
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Traveler usage?

I adjust the traveler and backstay more than I adjust the mainsheet even when daysailing single-handed.

Jeff
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Old 09-06-2003
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Traveler usage?

You didn''t mention whether you were using telltales on the main.

I have four tell tales on the leach of my main...getting them to fly properly gives me valuable feedback on whether the adjustment to the traveler or mainsheet was what I needed for better sail trim.

Fairwinds,

Jim
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Old 09-07-2003
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Traveler usage?

Humpwalker,

The mainsheet traveler is used to optimize the width of the slot between the mainsail and the jib. By precise adjustment of the traveler, you can ensure that the slot between the mainsail and jib is neither too wide nor too narrow to accept the volume of air that is being directed through it. The width of the slot must be correctly adjusted in order for the sails to generate their maximum amount of power. You should adjust the jib correctly for the course that you will be sailing, and then adjust the mainsail until the jib just begins to backwind and lift the luff of the mainsail. When that happens, you know that the width of the slot is just right.

When the windspeed increases, and the boat becomes overpowered, you can narrow the slot and reduce the amount of power that is generated by the sails by easing the traveler to leeward. You can also narrow the slot and reduce the amount of power by easing the mainsheet, but that changes the shape of the mainsail in ways that are not helpful. By correctly adjusting the relationship between the mainsail and the jib, you also maximize the boat''s ability to point.

Also, when you bear off the wind from a beat to a close reach and you ease the jibsheet, you are opening up the slot between the mainsail and the jib. By adjusting the traveler to leeward, you can optimize the width of the slot for that course. As you bear off even further (beyond the range of adjustment of the traveler), you need to ease the mainsheet to adjust the width of the slot, and you use the boom vang to control the shape of the mainsail.

If your sails are badly trimmed, and you suddenly correct that condition, then the difference will be enough to register on your knotmeter. But, if your sails are basically trimmed correctly, and you are making the kind of fine adjustments that a skilled racer would use, those fine adjustments can''t be measured by your knotmeter. Your knotmeter isn''t accurate enough to register differences in the range of an umpteenth of a knot. You have to read the authorities on sail trim, learn the basic principles, and take it on faith that, if you follow their advice, the boat will go minutely faster and point minutely higher. The only way that you can know for sure those techniques are working is by comparing your progress with the progress of other boats or racers, to see whether you are consistently gaining on them or falling behind.

Moving the traveler to windward and easing the mainsheet in light air is only helpful so long as the width of the slot is optimized. If it widens the slot, it could be detrimental. Your first concern should be to shape your sails as full as possible and to get the width of the slot right. Then you can make slight adjustments to the mainsail shape to power up the mainsail to the nth degree. But don''t expect to see or feel any resulting increase in speed.

In my opinion, there isn''t any difference between the basic techniques that a skilled racer and a skilled cruiser would use. The same sail trimming techniques that help a racer drive efficiently to the windward mark also help a cruiser claw off a lee shore. The same techniques that get a racer around the course ahead of the competition will get a passagemaker to the destination three days ahead of schedule. You don''t have to learn all the sophisticated sail trim techniques to enjoy sailing, but the more you learn, the more efficient and safer sailor you will be.
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Old 09-07-2003
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Traveler usage?

I don''t know how much in vogue the "slot effect" theory is these days with racers or theorists. Sailormon is probably correct in saying that making the "slot" too small will reduce lift of the headsail/mainsail combo. The interaction of headsail and main is one that has certainly generated a lot of "wind", but Sailormon is certainly correct in generally arguing that you have to consider the two sails as working together, and try to optimize the performance of both for best performance of the boat.

You don''t say whether your boat has a boom vang or not (a control line which allows downward force to be exerted on the boom, usually attached between a point near mid boom and a point near the base of the mast). The presence or absence of a vang will determine how much use you can get out of your traveler.

Without a vang, the traveler is your best way to control the angle of attack between the main and the wind, particularly when beating to windward. If the wind shifts and you compensate by easing the sheet, your sail shape will change. If it was well shaped before, it will no longer be so. A vang-less boat does best to play the wind shifts (or adjust course) using the traveler to keep the mainail''s angle of attack optimized.

A boat with a vang on it can "vang-sheet", usually in a stiff breeze: tighten the vang to flatten the sail, and use the sheet to control the sail''s angle of attack. If the vang is set rather loose for light winds, however, your sail shape may change if you sheet in too tight in an attempt to get the sail angle (boom angle) close to the centerline of the boat. In light air, a traveler is useful to allow a full shape in the main (having an eased sheet) while pulling the boom to windward until it is centered for good pointing ability.

To some extent downwind, the traveler will also replace the function of a vang, allowing you to shape the sail with the mainsheet while having the proper angle of attach relative to the wind. Alas, most travelers don''t have enough range of motion to allow a fairly broad reach with flattened sails; this is where having a vang is a real advantage.

Allen Flanigan

Alexandria, VA
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Old 09-07-2003
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Traveler usage?

Sailormon 6:

With all due respect, reading you post it is clear that you are way too obsessed with the slot, don''t understand the concept of powering up or down a sail plan, and really don''t seem to understand the role of the traveler in powering up or down the sail plan.

While closing down the slot too far can in fact slow a boat down, the slot has nothing to do with depowering the rig, as least as the term ''depowering'' is used in sail trim terminology.

In a general sense, there are a lot of factors in powering up or down a sail but the two biggies are the depth of its camber and the angle of attack. The deeper the camber (curvature of the sail) the more drive the sail develops, but along with drive (which is the forward component of the force generated) with increased camber comes a higher side force as well. This sideforce causes heeling and leeway. In really light air, the air flow lacks sufficient energy to flow around a sail with too deep a camber. As the wind picks up, you can introduce deeper camber which is how you ''power up'' a sail. Powering up involves and easing of halyards, outhauls,and backstays.

As the wind builds, so does drive but at some point hydrodynamic drag becomes the limit on speed, and at this point additional drive is not necessary. As this point is approached heeling becomes excessive. As the boat approaches this point the sails need to be depowered. To depower halyards, outhauls, and backstays are tightened. This pulls fabric out of the body of the sail, flattening the sail. The sail produces less forward drive, but it also produces less side force.

The second aspect of this discussion is angle of attack. For any given wind and sailshape, at any point on the sail, there is a proper angle of attack. If the angle of attack is too flat, the sail luffs, and if the angle of attack is too steep, the sail generates less lift and more drag and greater sideforces causing more heeling and leeway.

Because of gradiant wind effect, (slower air near the water than higher in the air due to the friction between the water surface and the air above) in light air, the apparent wind angle felt by the sail will be different at the head of the sail than at the foot. The apparent wind at the foot of the sail, will appear to be more forward than the air at the masthead. To allow the sail to have a proper angle of attack twist is introduced into the sail so that the upper part of the sail has a different angle of attack than the bottom of the sail. Here is where the traveler, backstay, and the boom vang come into play.

By bringing the traveller to windward, the pull of the mainsheet becomes more horizontal than vertical. In doing so, the boom is held inward toward the centerline, but the boom is allowed to lift a little, and that lifting eases the tension on the leech of the sail allowing more twist to develop.

As the wind builds, gradient effect generally becomes insigificant, so the whole leading edge of the sail wants the same angle of attack and in general, that angle of attack needs to be much flatter than it would be in moderate winds. To unify the angle of attack, the traveller is lowered to leeward and the mainsheet tightened, which increases the downward force on the leech of the sail. This increased leech tension removes the twist from the sail. As the wind builds the angle of attack can further be lessened by lowering traveler further to leeward. As you bear off on a reach, the traveller can be further lowered to maintain the proper angle of attack without powering up the sail, but at some point the sail needs to be eased broader off than the length of the traveller can permit while still generating the proper downward force, at that point the Vang takes over the main role in controling twist and the sheet then simply controls the overall angle of attack of the sail.

Simply easing the mainsheet in a strong breeze does allow the head of the sail to twist off and reduce heel, but it comes at a price. In easing the sheet the boom rises and allows more fabric into the body of the sail increasing power just when you need to reduce power, and also in order to obtain enough drive, the lower portion of the sail is overtrimmed developing a lot more weather helm than would occur with proper sail bladed out sail trim.
The backstay tension (especially on a fractional rig) can be used to depower the rig further. On any rig, even one with a stiff mast, tensioning the backstay removes sag from the forestay and is doing so, draws fabric out of the sail in a horizontal direction, flattening the jib and depowering it. As the forestay is tightened the mast moves aft and that also changes the relationship between the jibsheet lead and the head of the sail, allowing the leech of the jib to open slightly, reducing the angle of attack of the upper portion of the sail. On a boat with a bendy rig, and more dramatically and controllably on a fractionally rigged boat, as backstay tension increases the mast bows forward, in doing so it also draws fabric out of the sail depowering the sail in the same manner that tightening the forestay flattens and depowers the jib. Also similar to the jib, the masthead moves aft as the backstay is tightened and that opens the leech slightly at the head of the sail, easing the angle of attack and further reducing heeling, weather helm and leeway.

There is a tendancy to dismiss this as ''racer stuff'' but these kinds of subtle sail trim adjustments can make for a much more comfortable and controlable passage as well as adding significantly to the speed of the boat.

Lastly, really disagree with the idea That "if your sails are basically trimmed correctly, and you are making the kind of fine adjustments that a skilled racer would use, those fine adjustments can''t be measured by your knotmeter". Small adjustments to backstay or traveller positions can tremendously reduce weather helm and heel angles. On my prior 28 footer, these fine tuning items were good for a half knot or more, and on bigger boats or in higher winds, these kinds of minor adjustments can yield ennormous gains in speed.

Respectfully,
Jeff
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Old 09-08-2003
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Traveler usage?

Hmmm. I suppose Jeff that you may be correct under really light conditions, a sail with deeper camber will stall because the air cannot "follow" the shape of the sail; i.e. the sail cannot "accelerate" the flow (get it to change direction, thus generating lift force). I''ll have to experiment with this next time I''m out on the Potomac on one of our notorious light air days. My acquired understanding from reading tuning guides is that in "light" air, as opposed to "heavy" air, powering up involves making the sail shape rounder. Steve Colby''s theory is that faster moving air has a harder time following a rounded sail shape and will be more likely to "separate" from the sail, stalling it. But your sentence regarding "powering up" seems absolutely correct: Ease halyards/downhauls, outhauls, backstays to power up in lighter air. This should give the sail a rounder shape for maximum lift. And, as Jeff points out, as the wind builds you reach a point where you have all the lift you can handle and need to depower the sail by flattening it.

Check out the following guides for mainsail trimming and shaping:

http://www.vsf.vvv.com/training/Racing/main/basic.htm

http://www.sailingusa.info/sail_shape.htm

Here''s a good guide for those who lack a vang:

http://www.quantumsails.com/pdf/THE%20MAINSAIL%20TRIMMER%20AND%20THE%20TRAVELER.pd f

Here''s Dan Dickison''s two part article on controls for the mainsail other than the traveler and sheet:

http://www.sailnet.com/collections/articles/index.cfm?articleid=ddcksn0318
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Old 09-08-2003
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Traveler usage?

Jeff_H,

Your discussion is, as usual, thorough and technically sound, but, if Humpwalker is really a beginner, it might have been more complex than he needs at this time.

I’m not a naval architect, or sailmaker, or physics professor, and I don’t think Humpwalker expected me to be otherwise. I’m a retired lawyer and weekend sailor who has, for many years, had consistent racing success wherever I have raced, and who enjoys sharing what I know with new sailors. Like most people, I am impressed by the depth of your understanding of sailing technology, and grateful for the generous contribution of your time to the forum, but your comments on my post are grossly unfair, plainly wrong and mean-spirited, and I really don’t understand what prompted them.

You begin with the assertion that “ …you are way too obsessed with the slot.” How do you know the amount of importance that I attribute to the slot? Are you saying that adjusting the slot is unimportant? The only clue that I gave to my assessment of the relative importance of the slot is when I said that, in light air it is more important to adjust the slot than it is to tweak the shape of the mainsail in the manner that Humpwalker suggested. I said, get the slot right first, then tweak the mainsail. Do you disagree? Should Humpwalker allow the mainsail to luff while he is fooling around trying to shape it?

Next, you claim that I “…don''t understand the concept of powering up or down a sail plan, and really don''t seem to understand the role of the traveler in powering up or down the sail plan.” Later it becomes apparent that you are really quibbling with my use of the term “depowering.” If you will re-read my post you will see that I never used that term. What I said was “When the windspeed increases, and the boat becomes overpowered, you can narrow the slot and reduce the amount of power that is generated by the sails by easing the traveler to leeward.” Either your sails are “harnessed” to the wind and generating power, or they are “disconnected” from the wind, and flapping uselessly. Do you disagree with my conclusion that easing the traveler to leeward reduces the amount of “power that is generated by the sails?” Is it your opinion that the sails generate more power when you ease the traveler to leeward of the optimum position, in strong winds?

You close by saying that you “…really disagree with the idea that ‘if your sails are basically trimmed correctly, and you are making the kind of fine adjustments that a skilled racer would use, those fine adjustments can''t be measured by your knotmeter.’" My opinion was expressed within the context of the situation presented by Humpwalker. He was trying to slightly tweak the shape of the mainsail in light air. You cannot expect such a minor tweak to register reliably on a knotmeter in light air conditions. I agree that tweaking the mainsail and jib in a variety of ways can, cumulatively, make a significant, observable difference in boat speed, especially in stronger winds, but that was not what Humpwalker was talking about. He was talking about making one little tweak, and then looking at the knotmeter to see if it registered a change in speed. The readings of a knotmeter can be helpful, but are also imprecise and ambiguous. It’s often difficult to determine whether a change in boatspeed is due to a change in sail trim, or to a change in windspeed, or to wave action, or to some other factor. However, there is no ambiguity when the bearing to your opponent changes.
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Old 09-08-2003
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Traveler usage?

jeff.
a very well presented explanation !!!
eric
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Old 09-09-2003
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Traveler usage?

Hello Sailormon6,

I have gone back and reread Humpwalker,your original post and my response. To begin with I sincerely apologize to you if you read my response to your original post as "grossly unfair, plainly wrong and mean-spirited, and I really don’t understand what prompted them." I really did not mean them that way. My comments were meant to answer the original question as it was asked dealing with use of the traveler in the wide range of conditions encountered by a weekend sailor. My critique of your post were not intended as a personal attack, but were intended, for your sake, to correct some errors in thinking that your posting appeared to making.

As I read your original post I felt and still feel that the question was about how to use the traveller under conditions that an average weekend sailors is compelled to adjust the traveler. In rereading your response I felt and feel that your post missed the key point in responding to the question at hand, namely that the traveler only does two things, control twist and control angle of attack. (I elaborated beyond those two items so as to put the concept of twist and angle of attack into perspective.)It is for that reason that I said, "You....really don''t seem to understand the role of the traveler in powering up or down the sail plan". That probably should have been phrased "Your post does not explain the role of the traveler in powering up or down the sail plan" which is at the heart of the question being asked.

I still think that your post places too much emphasis on the slot. You spend a lot of time talking about optomizing the width of the slot. Except in light air, the slot shape plays a pretty minor part role sail trim. If you reread your post, with nearly every suggestion of a change in sail trim you talk about the shape of the slot. At the same time your post never really talks about the sail trimming factors that predominantly control drive and side force, namely camber, and angle of attack. That was the point of my comment, "that you are way too obsessed with the slot". That comment probably should have read "Your post appears to be way too obsessed with the slot."

I do admit that perhaps I misunderstood what you were saying in your post when you were discussing what happens when a boat is overpowered. You discuss a couple of ways of dealing with being overpowered but again only as they affect the slot, without ever talking about how they affected whether the boat was too powered up or too bladed out which is far more significant to how the boat is performing.

Again I should probably have said "Your post does not appear to understand the concept of powering up or down a sail plan" rather than say that you didn''t seem to understand these concepts. My point here was that for all of the discussion within your post, there was never any reference to the concepts involved in powering up and down and that the basics of sail trim really deal with shifting gears between being appropriately powered for the conditions and point of sail.

Lastly, you and I appear to disagree on the accuracy of a knotmeter as a sail trim tool. This may result from how we each use a knotmeter and the equipment we are using in conjunction with the knotmeter. I use the knotmeter a lot. I use it in conjunction with a wind instrument set to reflect the true wind. I keep my eyes moving between the knotmeter, wind instrument, the sails (mostly the teletales), and the masthead fly. Each gives different information, but cumulatively it is pretty easy to correlate speed with windspeed and direction to develop a sense of the performance of the boat for that windspeed (which will sometimes be different from one tack to the other)and sea state. While it is true that in many, if not most, conditions these instruments will jump around a lot, it is not hard to develop a sense of the pattern of change and to tell if even small adjustments help or hurt that pattern. while individual minor changes may result on small performance gains, the combined impact of these changes can often result in big gains. This is especially true when pointing or when sailing at deep wind angles.

Again, I apologize if my comments came off as being a personal attack. They were in no way meant as such.

Respectfully,
Jeff
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