side stay positions

[flynow1]

Shroud Positions
I have a set of Victor Sails and have not been able to get hold of Jake Leo. I bought the boat used and have not been able to get it balanced. The mast step was mounted way wrong!
The question is what would be a starting position for the shroud positions attaching to the rails. The mast step was installed in the wrong position and had to be moved forward about ½ of an inch to get the 25 ½ in center hole position. With the step being way aft the weather helm was nasty. I don’t seem to be able to find a suitable picture of shroud placement anywhere nor can I find the answer about shroud positions in the forums. I read the rail should be installed so that the #3 hole is adjacent to the 25 ½ center hole position. Does that mean one of the 3 shrouds should be set in that #3 hole. How about the other 2, where should they be for a good starting point.
Thanks

[kahle67]

My lower shrouds are attached one inch behind the uppers which are adjacent to my favorite mast step position. Not sure about Jake's mainsail luff curve but some sail makers in the past required a good bit of lower shroud tension to prevent over bend wrinkles so more spread between the shroud attachments was beneficial.

[flynow1]

thanks

[rs vernon]

I am glad Reichard posted. But I will put this in anyway as it might be helpful to you and others who do not have access to the good book for tuning help.

Let me try to help. I think you are using a Sails ETC round mast as opposed to the teardrop mast which is by far the most common mast in the class. Your mast is probably more bendy sideways due to being thinner wall and bendy fore and aft due to being round.

The info below talks about lower-lowers which most people do not have on their rigs. I use them on some rigs and on some rigs I use check stays (pulling aft) about half way up to the lowers (on the mast), to control mast bend in the lower part of the mast when high bst is needed for controlling jibstay sag and jib boom lifting.

The advice (written for teardrop masts) is to tension the backstay to give proper jib stay sag in the existing wind conditions, and then pull forward or aft with the lowers – by placement in the stay racks and tension – to give proper mast bend in the lower, middle and upper parts of the mast.

Here are some words and paraphrasing of words from the bible:

The boat should sail upwind with an angle of heal of about 25 to 30 degrees. If yours is healing less than that, you need more power – deeper shape in the sails. Optimizing the East Coast 12-Meter says to always be asking yourself, do I need more power. Then when the boat is wanting to consistently heal more than 30 to 35 degrees sailing upwind, it is time to start to depower - flatter sails/more bst for control of jibstay sag and more mast bend for a flatter main.

my opinion - this is gold - (The nominal main luff curve can be found by sail testing.) Adjust the mast bend using the controls discussed below so that over-bend wrinkles just appear. Now pull the mast back until the wrinkles just disappear. Do this for both the upper and middle mast sections if possible. The mast bend so obtained is the low entry angle, low camber, 'point mode' setting for moderate and steady winds. Moving the point of the mast (me - I guess he means the furthest forward point of the bent mast) back about 1/8 inch gives the nominal main setting (which matches the MLC) and another 1/8 inch or more back is a light air or acceleration mode setup.
Once the desired main luff curve is known, the mast should be set up to produce this shape. You do this by adjusting backstay tension, shrouds, jumper stays and vang tension.

The backstay is set, not to bend the mast to match the main, but to adjust jibstay sag and indirectly to control jib boom lift. When tuning the mast, it's helpful to think of which controls increase mast bend and which controls decrease it.

To increase mast bend
Increase - control / location of bend / notes
Jib stay via bst / upper and middle panel / increase bst to increase
Jumper stays / upper panel / loosen
Boom through vang / lower and middle / dynamic effect
Upper shrouds / middle panel / only if forward of mast and very tight
Spreaders when angled aft / middle panel / not common on EC-12
Lowers / middle panel / only if attached well forward on chainplates

To decrease mast bend
Jumper stays / upper panel / tighten
Lowers / middle panel / move aft on chainplates and/or tighten
Lower-lowers / lower panel / move aft on chainplates and/or tighten
Upper shrouds / middle panel / only if aft of the mast butt and very tight

Setup

Our approach is to begin by setting the backstay to give the proper jibstay sag based on the jib’s measured luff allowance (MLA) in the expected conditions. Adjusting the backstay will be discussed in detail in the next section of this chapter.

For now, assume that you have properly set the backstay. If significant mast bend is needed, there will be a minimum backstay tension below which the main will not set properly. Now tension the lowers to produce the desired mid-mast bend. When sailing, a convenient visual check of your setting is to watch the entry angle at each draft stripe. Refer to a standard sailing text to see what this should look like. Briefly, to Decrease Mast Bend: if you see a knuckle or discontinuity at the luff in anything but light air, the mid mast needs to go further forward. Set the lowers with equal tension. The uppers don't really need to be adjusted from their nominal position, unless you like a sloppy light air setup. If you need more aft force in spite of high lowers and lower-lowers tension, move the lowers aft on the chain plates. Conversely, if more forward force is needed, move the lowers well forward on the chain plates, maybe fwd of the mast.

The tension on the lowers must be adequate in relation to the uppers to prevent the midsection of the mast from sagging to leeward. If the main requires considerable mast bend (e.g., 1/2 inch), in light air, the lowers may have to be quite far forward. This allows adequate tension on the lowers yet does not pull the mid-portion of the mast too far aft. Because the lowers are critical to fine tuning fore and aft mast bend, they should be easy to adjust. We think this is one of the keys to proper main trim.
Next adjust the upper mast bend with the jumper stays. The jumpers will have to be readjusted when the backstay tension is changed. Since the lower tang of the jumper stays pulls the mast forward, the lowers may have to be retensioned after the jumper stays are set to get the mast back to the desired position.
Now tension the lower-lowers to control the effect of the vang. If you are an advocate of "vang sheeting', where the main sheet exit is up on a post, the lower-lower loads can be very high. If you don't have "previously determined fast settings", use the recommendations for setting mast bend in this section. It makes allowance for whatever luff curve your main has. You can check your shroud settings with the tension gauge if you wish. The boat should now be close to its optimal tune, without even a test sail!
Finally, nylon stop nuts on turnbuckles are very helpful. They can be left at the full in position as a reference and the lowers and lower-lowers backed off for light air, where vibration is unlikely to change the setting.
Backstay adjustment
Most EC-12 skippers use backstay tension primarily to bend the mast to get the desired mainsail shape. The focus is on the main setup, except in light air, where we have occasionally seen the backstay set loose so that the jibstay will sag to its target value.
Here is our tuning method that may be suitable for your sailing style. The goal is to achieve the desired shape for both sails. Whatever system you use, a tension meter makes setup easier and more repeatable. You will have to develop a feel for jibstay sag based on experience, since (I assume) you do not use a tension meter and JLA or Jib MLA / wind speed chart.

As the wind varies, you can fine tune your jibstay sag between races. Let's assume you set the backstay tension at four pounds onshore, and after a few races the wind drops. The table now suggests that three pounds BST is the proper setting. So you readjust the BST (and maybe readjust a few other things like the vang and main sheet length which are slightly affected by any change in BST and mast bend).
Using a tension meter you should adjust BST in half pound increments because you will probably not notice a change in performance from anything less. It's fairly easy to keep track of BST, even without the BST gauge. However, check it during lunch break to confirm the setting.

Here is the seat of the pants way of seeing problems or success with respect to jibstay sag and jib entry angle. I think this is gold too.
It's nice to have some visual conformation of the backstay setting. There are two ways of doing this. The easiest way is to watch the entry angle of the jib. If you see a knuckle or discontinuity develop just aft of the luff, the backstay is too loose. It's harder to judge when the entry angle is too low (and the BST too high). In this case watch the width of your sailing groove. When the windward and leeward jib telltales alternately stall with only the slightest variation in course, the BST is too high. When you notice entry angle problems or steering problems related to the width of the groove, recheck the table. Resetting the backstay based on the table and the appropriate target jibstay sag should solve the problem. (Without a tension meter and the table, you will have to do it based on what you are seeing on the water.)

It is too bad that Rick West never wrote the words that he was planning to write on his great website concerning tuning the multi-spreader/Vector sails rig.

Scott

[flynow1]

Scott
Thanks for the info.
Robert had mentioned the tuning guide and said he was going to send me a copy. Must have fallen through the cracks.
Yep, round mast.
I had fully expected Jake Leo to be pretty helpfully. A couple of months ago he had had said to call him but I've waited until now so I would have a better understanding of what he was telling me but as luck would have it, I can't find him now! Oh well.
I've printed all you sent and will start digesting it.
Thanks again.
Skip

[rs vernon]

I hope I am not overstepping my bounds, but it seems to me that great info like this should be available to people who have joined the class within the last 11 years, not just old timers, This is from Model Yachting Issue 145. Fall 2006

Sail Tuning and Trim – Switching Gears and Sailing Fast

by Reichard Kahle, Charleston SC
One of the most difficult things about sailing model yachts is the fact that you are not on board to see what is going on. Yes, it is hard to judge distances to marks and competitors when far away, but getting your sails trimmed right is certainly one of the biggest challenges. This article is an attempt to explain my thoughts and ideas on initial setup and the tweaking and tuning that follow as the wind velocity changes, specifically for the EC12 class. I will say that I have developed an eye for how things should look, but my mouth and fingers often don't follow well. There is still plenty for me to learn.
So, you have arrived at the lake early in the morning to get your boat rigged and prepared, well before the skipper's meeting. A layer of fog is hovering above the racecourse and the only ripples on the water are from ducks or the fountains at Elon. You set your sails up for light air and wait for the breeze to fill.
What I look for, as a starting point, are the middle battens on the mainsail parallel to the boat's centerline and the leech of the jib pointing straight aft. These adjustments are set with the vang and the topping lift. The problem is that when the boat lies on its side, you have only gravity to help you judge the amount of twist in your sails. This is not a big deal in the light stuff, as there is very little pressure while sailing anyway. It is virtually impossible to predict on land what the actual pressure will do to your sails on the water as the wind builds. Sometimes, I will do what I call armchair sailing. At home, while examining a new set of sails or getting pumped for a regatta, I actually sit in my favorite recliner with the rigged boat on my lap and flop the sails back and forth from one tack to another to simulate air pressure. The wife and kids often think I am flat-out crazy. At the lake, you can do the same by resting the keel on a towel laid on the ground or by just holding the boat up in the air. This simulates a view of being on deck, looking up at your sails.
Most of the venues where we sail on the east coast are located on small lakes with wind obstructions and are rarely in open water. The majority of the time the breeze might be stronger around the bottom of the course, but lightens as you get near the top mark. If you are too tight in the lighter air near the weather mark, you are going to get killed. There is often much maneuvering here, and acceleration is key. At the same time, if you don't tighten the leech of the main going up hill in the breeze, you are going to be out pointed.
(The next paragraph talks about Sheet Vanging or what Optimizing calls Winding Up.)
Therefore, switching gears and twist adjustment are important. Since you cannot adjust your vang on the go, I rely on sheet vanging. This is where the mainsheet is over tightened so that the boom is actually pulled down towards the deck. The R MG sail winch with the spiral drum really comes to play on the EC12 in these conditions. The fine adjustment allows you to find the sweet spot in order to keep your telltales on the leech of the main flying. is what you need to do to set up for this. The fine trim on the sheet stick of your transmitter should be all the way in when using the RMG winch. Adjust the bowsie on your main sheet to the appropriate leech tension (twist) for the maximum wind speed that you expect to see in the conditions under which you are sailing. Ease your sheets a hair with the trim lever or stick. Your vang should be set so that the boom lifts a little, giving you the nominal twist setting for the pressure you expect to see. Sailing the "12" in this fashion brings the main boom almost to centerline. Be aware of your boat speed in relationship to competitors around you, for it is really easy to stall out in this mode. If you feel slow, let off a bit and go fast. If you are moving well, tighten up and point high. If your sails are worn and abused, stick with your original plan.
One last thing I want to mention is the use of the jib-trim feature allowed in the EC12 Class. There is a misconception among some that tightening up the jib trim will make you point higher. It is true that trimming the jib in further will reduce the entry angle of the sail, allowing you to sail a little closer to the wind before the jib begins to luff. However, being that the EC12 has a fractional-rig sail plan, most of the drive comes from the mainsail. The pointing ability of the boat is dependent upon your ability to properly trim the main. Once you have achieved this, the general rule is that you trim the jib to match the main. First, adjust the topping lift so that the leech of the jib matches the point of maximum camber of the main. In light air, go for a larger slot to allow for better air flow with the jib boom pointing just inside the shrouds. As the wind picks up, trim the jib until it causes the main to backwind and then ease it back out slightly. In the heavy stuff, you can over-trim the jib and ease the sheets slightly to de-power the main, which helps to hold the bow down and reduce weather helm, be it upwind or on a reach. In most conditions, unlike the main, I like to set the bowsie adjustment on the jib sheet slightly loose, or as loose as I would want it sailing upwind in the given conditions. then use the trim feature to dial it in. Rarely would I ever allow the jib to be sheeted out beyond the normal setting. In fact, the jib trim mechanisms in the boats that I have built are not designed to do so.
Without a doubt, there are many factors that contribute to podium finishes besides sail trim. Fortunately, with the class as well documented as it is today and the amount of helpful information available, most of boats actively racing are well built and properly ballasted. With a good set of sails and some general tuning knowledge, skippers can now get their heads out of their boats, focus on tactics and boat handling, and start winning races. In my opinion, the class has come a long way in the past six to eight years. There used to be larger performance gaps in the boats to take advantage of, but that is no longer the case. These days, with a bad start and a mix-up in the crowd, it's all over.

Scott

[rs vernon]

More from the book Optimizing. In total this is a lot of information, above and below, but it is not 240 pages like the book itself.

Let me put the following paragraph in here a second time, because this is one of the basic/vital paraphrased bits of advise in the book and the whole tuning process is based on it. It is a call for us to use judgment in our tuning and that is one thing that separates the fast guys from the rest of us. It is easier to do well in races with a fast boat than a slow one, and a big part of being fast on the water is tuning.

The boat should sail upwind with an angle of heal of about 25 to 30 degrees. If yours is healing less than that, you need more power – deeper shape in the sails. Optimizing the East Coast 12-Meter says to always be asking yourself, do I need more power. Then when the boat is wanting to consistently heal more than 30 to 35 degrees sailing upwind, it is time to start to depower - flatter sails/more bst for control of jibstay sag and more mast bend for a flatter main, tighter stays to control sideways mast bend, wider sheeting angles.

Here are some more words from Optimizing – twist – sheeting angle – downhauls / outhauls - balance/helm

The book puts a lot of emphasis (and page space) on talking about twist. The information might seem to be confusing – "you might do this, but no, do that" – but if you study it and apply it, hopefully it can work for you.

Twist – hard to get it right due to lack of easily observable clues to proper adjustment and because changing twist can dramatically change the balance (helm feel) of the boat. (me - I repeat this same passage down the page a bit.)

Minimum twist setting - Consider this as having the aft end of each main batten pointing straight aft. Even in these no waves, moderate wind conditions you can get badly burned with this setup. The top of the main may be completely stalled out. Here is an alternate method currently used by a few SMYC skippers. You will need silk or inked clear Micafilm wind rags attached to the ends of the top two mainsail battens. Besides their general usefulness described in most full size sailing texts, we use them to help set the main twist. me – clear Micafilm is no longer available.
Incidentally, you must adjust or at least confirm twist settings by sail testing. On the water there is a change in apparent wind angle with height while on shore there is no such change (in the absence of wind shear). To understand this, remember that there is a change in the wind velocity with height. When sailing, the wind at the foot of the sail comes from further ahead than at the masthead because of the wind generated by the boat itself. Imagine what would happen if there were no true wind at the foot (an exaggerated velocity gradient) In other words, if you set the vang just right on shore it may be too tight when sailing.
Our current feeling is that the "full on" vang position is found by gradually tightening the vang until the top main telltale just stalls at the same time that the leeward jib telltales stall when you slowly bear away. This means that the jib is suffering from leading edge stall when the top of the main is completely stalled out. There are only a few special conditions when you would ever want to use less main twist.
After setting the vang, the jib twist can be set by watching the wind rags. Many sailors luff slowly, adjusting the jib twist with the jib topping lift, (JTL) to get the top and bottom windward telltales to lift at the same time, a so called even break. It's often more accurate to slowly bear away while watching the leeward jib telltales. The minimum twist occurs when the top leeward wind rag stalls close to, but no sooner than the bottom one. (Me- It seems like we might want to re-check whether the main twist is really correct at this point since the jib twist has been changed and the first part of the exercise was to adjust the vang so that the main is happy compared with the jib.)

Twist
Twist is one of the most important elements of sail trim on an EC—12. It's hard to get it just right, in part because of the lack of easily observable clues to proper adjustment and also because changing twist can dramatically change the balance of the boat. In order to make any conclusions about the effectiveness of a change in twist you should restore the boat to its previous balance by moving the rig fore or aft or by adjusting the rake.

Adjustments Not Radio Controlled
Minimum twist setting - Consider this as having the aft end of each main batten pointing straight aft. Even in these no waves, moderate wind conditions you can get badly burned with this setup. The top of the main may be completely stalled out.
Here is an alternate method currently used by a few SMYC skippers. You will need silk or inked clear Micafilm wind rags attached to the ends of the top two mainsail battens. Besides their general usefulness described in most full size sailing texts, we use them to help set the main twist. me – clear Micafilm is no longer available.
Incidentally, you must adjust or at least confirm twist settings by sail testing. On the water there is a change in apparent wind angle with height while on shore there is no such change (in the absence of wind shear). To understand this, remember that there is a change in the wind velocity with height. When sailing, the wind at the foot of the sail comes from further ahead than at the masthead because of the wind generated by the boat itself. Imagine what would happen if there were no true wind at the foot (an exaggerated velocity gradient) In other words, if you set the vang just right on shore it may be too tight when sailing.
Our current feeling is that the "full on" vang position is found by gradually tightening the vang until the top main telltale just stalls at the same time that the leeward jib telltales stall when you slowly bear away. This means that the jib is suffering from leading edge stall when the top of the main is completely stalled out. There are only a few special conditions when you would ever want to use less main twist.
After setting the vang, the jib twist can be set by watching the wind rags. Many sailors luff slowly, adjusting the jib twist with the jib topping lift, (JTL) to get the top and bottom windward telltales to lift at the same time, a so called even break. It's often more accurate to slowly bear away while watching the leeward jib telltales. The minimum twist occurs when the top leeward wind rag stalls close to, but no sooner than the bottom one.
So far we have talked about minimum twist settings, but how often can we set up this way? Not very often! These minimum settings will work in a four to six mph Juanita Beach thermal but at the more typical model yacht sailing sites with light and variable winds, you may take a quick trip to the back of the fleet with this setup. Many of the conditions in which we sail require higher twist. Some are:
- waves (heading varies so with higher twist at least some of the rig will be at the correct angle of attack)
- variable winds (at least some of the rig will be at the proper angle of attack)
- need for acceleration (force vectors of twisted portion of sail directed more forward)
- over sailed (a fisherman's reef, but note the downwind rolling problem of an EC—12)
- wind shear (different twist requirements on each tack — see if the telltales behave differently on each tack to check for this)
Clearly, for a lot of our racing more than the minimum twist must be used, but where to start? Kelly Martin advises newcomers to adjust their vang so that the aft end of the top batten makes about a 15 degree angle with respect to the boom. This setting will give good protection from wind variation and waves, and will give good acceleration. Nonetheless, since the top of the main is in effect not fully sheeted you will be giving up a small amount of top end speed when conditions are appropriate. You may want to just live with this problem at times, knowing that you will have a speed margin when the wind gets fluky.
On the other hand, you simply cannot allow the whole fleet to sail over you coming off the starting line Here is one solution for this problem. Assuming that all other adjustments on the boat are appropriate, begin sail testing with the main twist set to Kelly's recommendation or perhaps 5 degrees more if it's really light and variable. If you are fast enough compared to boats that have been your equal, then sail with the twist as set. If you are slow and want to risk getting stuck with too little twist if the conditions should change (very bad), slowly tighten the vang as you continue to sail test. Make sure you don't go under the minimum twist settings. You do this by watching the telltales for the clues described previously.
Of course the skipper you are tuning against may be doing the same thing, in which case you will both tune yourselves to the back of the fleet. It's better to check your tune against several boats and note their twist settings. Depending upon whom you tune against, you may find that your setting is quite close to the minimum even if you would like to have more twist. Remember that as you decrease twist (vang on) weather helm will increase. In practice you can adjust the vang until you get it about right, then check and readjust the jib twist, while making sure you have what you think is the correct amount of helm. Adjust the helm by changing the CE (move the rig forward or aft) if necessary.

Radio Control of Twist – See the Model Yachting doc written by Reichard for “sheet vanging” information. Sheet vanging is written up in Optimizing, but Reichard ‘s version is more easily understood and applied. It is posted in this thread directly above.

Sheeting angles upwind - Jib and Main Boom Sheeting Angles
me - Some words about the boat being willing to help steer itself upwind or not being willing - pretty interesting section.
Here is what will happen when you ease the mainsheet using a bowsie to get the recommended MSA. The main should be set so that it develops a very slight luff bubble when the weather jib telltales just begin to flutter. Now when the boat turns to weather, the main loses power before the jib, so the jib helps push the bow back down to the original course. If the boat is too low, the jib begins to stall and lose its contribution to balance. Again, the boat will try to return to the original course. This setup provides a nice feel and a definite groove. If you are short on speed, you may want to power up the sails more equally, at the expense of having such a nice groove. See the section on radio control of twist for the limits to this approach.

Table 4
Main and jib boom sheeting angle recommendations in degrees
Wind strength, sea conditions.......main sheeting angle MSA.......jib sheeting angle JSA
4-6 mph nominal.........................................5................................12
4-6 mph after a tack*...................................11 to 13........................15
4-6 mph, after winding up aka sheet vanging......2 to 3..........................10
light, fluky................................................ 7?...............................12 to 15?
4-6 mph with waves.....................................7?.............................. 12 minimum
Over 8 mph............................................... 7 to 15?....................... 12?
*trim back to nominal setting in 10 sec. for light to moderate wind, 5 sec.for heavy air

Our current recommendations for main and jib boom sheeting angles are shown in Table 4. Settings for "drag race conditions" (four to six mph, steady wind, no waves) are based on controlled sail testing. We have included our best guess estimates for other conditions, but since it's hard to do much structured testing at the extremes of sailing conditions, we don't have much useful data. Therefore Table 4 shows values for these conditions with a question mark. We suggest using a relatively high MSA, but at selected times (i.e no waves, consistent two to six mph wind), reducing the main twist until the top the main stalls just before the leeward jib telltales do. Hopefully this will produce a more elliptical load distribution to reduce vortex drag, which will overcome the loss in power at the bottom of the main due to the wider MSA. The sailing groove is still maintained. However, be careful about reducing twist like this. If you haven't seen enough of those graceful EC-12 transoms, try it in light fluky winds
Jib sheeting angles (JSA) must complement the main settings. The suggested JSA values shown in Table 4 again come from controlled sail testing. We have found that with proper sails, superior pointing without loss of speed can be achieved with the jib sheeting angle as low as 10 degrees. The 10 degree setting seems to be an absolute limit and you must wind up (explained shortly) to get there. You will need to know how to set your transmitter to get a specific jib sheeting angle as well as a specific main sheeting angle
We recommend that indicators of the JSA and the MSA be placed on the deck so that you can easily estimate the values. A little trig will help you set the marks, but if you "lost your trig table" see Table 5. Place your marks so you can sight vertically down from the end of the booms to estimate the angles Remember, these marks are for setting up the sheet length and the transmitter so that you will know how to get a specific boom angle without looking at the boat. For example, you need to know what trim lever setting will give an MSA of five degrees. You do not refer to the marks while racing

Table 5 Positioning of boom angle reference marks on deck
Degrees off centerline.....where to place marks. Multiply distance from axis by this number to find distance from centerline
5 for MSA.........................0.087
7 for MSA.........................0.12
10 for JLS.........................0.17
12 for JSA........................0.21
15 for JSA........................0.26
18 for JSA........................0.31

Outhauls and Downhauls
We have lumped these two topics together under the banner of adjusting the corners of the sail. These are important controls, but not as critical as those in previous sections.
Downhauls
Downhauls adjust luff tension. Some refer to these as 'Cunninghams', named after Briggs Cunningham who first used a cringle just above a fixed tack to set the luff tension. EC—12 skippers traditionally set the jib luff by using a bowsie on the jib halyard. Also, the main halyard is occasionally used to control the main luff tension. These halyard adjusters just add unnecessary aerodynamic drag, with minimal increase in convenience. If you want to go fast, clean up the rig; among other things, adjust the luff tension at the tack. We have found that this is easy to do if you lead the downhauls along the booms. For sails made of woven sail material, luff tension is a principal draft position adjustment. Composite sails are different. Luff tension has much less effect on draft. Because of this, many sails have been ruined by overtightening the luff in an attempt to make the sail into something that it's not. Compared to Dacron sails, Mylar sails are WYSIWYG. (What you see is what you get.) There is some draft control with mast bend or jibstay sag, but don't expect major changes from luff tensioning. Therefore, we set the downhauls to just take out the luff wrinkles. As the wind increases, you will notice new wrinkles in the lower portion of the luff. This gives you an indication of how much the whole sail stretches from top to bottom with more wind It is reasonable but not necessary to take out these new wrinkles.
There is one situation where a very snug main downhaul may be helpful. When oversailed the mast can be bent until over-bend wrinkles appear, thereby reducing the camber. Small over-bend wrinkles are then removed with a lot of downhaul tension. Bob Sterne demonstrates this clearly in his tuning video. There is risk to this setup, however. If the wind drops, the main may have a bad crease up and down the luff. One more caveat about main luff tension: sails are still being damaged by putting them in a hot car with the downhaul tight. Don't do it.

Outhauls
me - Bob tells us to set our outhauls using his term “belly”. I think it is easier to learn to do it by keeping track of how many fingers will fit between the boom and the sail foot. Perhaps we need to learn the fingers equivalent of 1.9 to 2.3 inches and under ½ inch of belly.
We now engrave a small scale on the boom so that outhaul settings can be quickly duplicated. When setting the outhauls we think it’s helpful to remember a generalization taken from vintage North Sails literature. Generalizations are not rigorous and are not right all the time, but they can still be helpful. Try this one: curvature equals power. You would think that a sailboat could always use more power, but that is not the case. With power comes drag. When sails produce lift, there must be associated drag. More lift —more drag. Until a boat reaches its design heel angle, it can use more power, but after this point drag becomes increasingly important. Even at the design heel, when waves are present, or the air is disturbed, more power is needed in spite of the extra drag because the boat is continually having to accelerate. For EC—12's, consider the design heel angle to be 25 to 30 degrees. Below this value, corresponding to wind speeds under four mph, have the camber of the bottom of the sail match the camber of the middle section. Typical cambers are 10 to 12% so the lower panel can have a belly of say 2.2 to 2.6 inches for the main, and 1.9 to 2.3 inches for the jib. Fine tuning the camber has not given us much reward. Regard the recommendations for camber as a continuum based on wind speed. Also consider your need to accelerate from disturbed air, frequent tacks, waves, etc. If you need to accelerate a lot, you need more curvature. Once the boat approaches its design heel, (25 to 30 degrees) in the absence of disturbing forces such as waves or dirty air, extra power doesn't help much because of the associated drag that comes with the additional force. By flattening the bottom of sail, a more elliptical load distribution can be achieved. (See the section on twist for more on elliptical load distribution.) Briefly, it minimizes vortex drag. Have you noticed how flat the bottom of the main is on full size AC boats? The theory seems to work. Jerry Brower and Larry have experimented with outhaul settings and have made the following tentative conclusions. With wind speeds from five to six mph, no waves, and undisturbed air, there can be a one to two boat length weather leg gain in 200 feet with the main outhaul set for 1/2 inch or less belly at the foot they found that the jib needed a little more camber; say one inch at the foot.
You must be cautious with this approach, which we nicknamed "playing America's Cup" If the wind becomes light, or if waves develop, you will be very slow. Continually ask yourself, "do I have enough power?" If you don't have enough-power, add curvature to the limits above. If you do have enough power (proper heel angle, no waves, clean air, and minimal need for acceleration), you may start pulling out the outhauls. Edit – I think that is great all around advice for sailing in marginal conditions.

Balance / Helm
When going to weather, many sailing texts advise adjusting the boat for three to five degrees of weather helm, but this amount is quite slow on an EC—12. With the add-on transmitter circuit described in the EC—12 Manual, we have had some opportunity to explore different helm angles while speed testing against boats of essentially equal speed. Here are our tentative conclusions. A note of caution: the values for beating represent the desired amount of helm once the boat is up to speed. An EC—12 will have significantly more helm before it reaches its target boat speed. If you plan to spend a lot of time accelerating (a lot of tacking, gusty conditions, etc.) you may want to put the rig a little further forward.

Beating, Light Air (0 to 2 mph)
Some weather helm is a must. The keel is near stall and "lowering the flaps" (like an airplane taking off) helps provide the required lift with less drag penalty. Because the lift is now created at a lower angle of attack the leeway angle is reduced. Weather helm in light air also helps the boat find the wind and will hopefully prevent you from sailing too low for 10 to 20 boat lengths before realizing it. About one degree helm seems an appropriate target.

Beating, Moderate to Heavy Air (4 mph and up)
We have convinced ourselves that one should aim for zero degrees helm, but if anything err on the side of weather helm. You will probably not notice a speed detriment with one degree helm. As you approach two degrees, there will be a loss that is significant on long courses often set at Juanita Bay and Coulon Park on Lake Washington. By the way, even Jerry Brower has finally given up tuning for lee helm.

Reaching
Overtrimming the jib is more effective than carrying a lot of helm In light air you can often balance the boat with the jib only. Do so if you can. As the wind increases you will have to add some helm to prevent the need to sheet the jib so tightly that it "cuts off the slot". Up to two degrees of helm seems to have little adverse effect so we use this amount freely. In heavier winds a practical maximum is about four degrees weather helm, beyond which it's probably better to ease the sails to reduce heel angle and thereby reduce helm. On heavy air reaches you can set three to four degrees helm, over-trim the jib some, then adjust the balance with the sail servo. It's sort of like power reaching on a full size boat with a good crew.

Scott

[rs vernon]

Size and location of telltales on the main leech and jib luff - per the book Optimizing
Telltales
Now is a good time to apply the telltales. If you do not use them, we think you should reconsider. You cannot use the sailing techniques discussed in Part Ill without them. We have tried and rejected lots of different materials for telltales. Ordinary yarn is not visible enough and it's too stiff. Audio cassette tape sticks to the sail when wet. Clear micafilm inked with a permanent marker is reasonably effective, but it lacks a little sensitivity in light winds. It's quite durable, however. Our favorite material for light air is #LS - 007 Rose Pink light weight model airplane silk, available from Sig Manufacturing Co. Of the colors available, this is by far the most visible. Don't unfold the silk. Just pull a little out of the package and cut off a stack of telltalès with your wife's rotary cutter. Olfa is one brand name. If your significant other doesn't have one, perhaps it would make a nice Christmas or birthday gift You will not believe how sensitive this material is until you try it. The telltales will move in the slightest wind. The down side is that they are not very durable. We expect to have to change them frequently. (Changing telltales all the time is nothing new for big boat sailors.) We originally cut the telltales about 1/4 inch wide. As we gradually learned how much the silk ones tell us, they have gotten wider and wider, in spite of the extra wind drag. We now typically make them 1/2 inch wide by 3 1/2 inches long. For the 1995 and 1996 Nats, Larry even made special 'CNats rags", 3/4 inch wide. Bob Wells ('95), Jerry Brower ('95 and '96) and Kelly Martin ('96) reported that they could still read them even at the corners of the course. This can be a real advantage.
Where to put them? Too many wind rags are distracting and liable to cause information overload. On the main, we attach a telltale (with 1/8 inch double stick sailmaker's tape) at the aft end of the top two batten pockets. On the jib, we use two pairs, one high and one low. They should be about 1 3/4 inches aft of the luff, so they will not wrap around the luff. For consistency, we place the starboard ones higher, with a separation of about two inches to improve readability. Also, they should be well away from the jib number and the draft stripes to avoid misreads. Bob marks the front of his port and starboard jib telltales with different colors so he can keep which telltale is which clear in his mind.

Scott