Smash! The sickening hollow noise of broken fiberglass thuds across the water. Heads turtle-duck between raised shoulders. Eyes reflex toward the epicenter. Two nearby boats have collided. Serious damage results, a sail is torn, a bow has pierced a hull. Fortunately, no one aboard either boat is making signs of an injury. "Four minutes" the mid-crew drones. "Stay focused", demands the skipper. Reluctantly the team turns their attention back to the game. "Number 25…do you see number 25?" shouts the foredeck. "Got em", responds the skipper. Seventy odd boats are kicking up sizable wakes as they reach back and forth across the starting line. Fluttering sails mix with roaring bow waves to vibrate the air. The sky is a checkerboard of white puffy clouds, and bright blue sky. White caps occasionally flash their teeth. The horizon is a sharp blue/gray streak. Everything is in motion.
A few moments earlier our team was lazily passing the time waiting to start the final race. Occasionally they would hold the boat head to wind and record the compass direction, but for the most part they were content to exchange polite salutes to their friends and rivals. They sought out smooth surfaces to sit on or improbable back rests to lean against. The mood was amiable if not politically correct. Four long race days, two practice days, an absurdly long road trip, and cramped lodging had made them weary. Any other group of primates forced to bear these hardships would have become hostile. But our group had managed to avoid that frailty. Inhibitions had slowly faded, and in its place grew a kind of bond, a bond based on a solitary goal. There was just one reality in front of them now. Hardship and sacrifice were trifles when weighed against the elation of victory.
Private thoughts belonged to a different place, a different time. Their vast repertoire of humorous tales had been exhausted. Conversation had reached astonishing new lows. No topic was too tasteless or too personal. They sailed up wind, tested the surface for tide, and set the spinnaker to make sure everything was rigged properly. Honest laughter punctuated the wait.
The prep gun changed everything. They jumped to their watches. Worn and tattered gloves wrapped bruised and callous fingers. The tactician stood up as high as possible and looked into the wind. Tired eyes searched for anything that might indicate a hint of what nature had in store, an imperceptible change of hue, a subtle shift in the pattern of white caps, or maybe an odd shaped cloud. The pin had recently become favored, but the tactician decided to avoid starting right at the pin. "The pin..." gloved hand massaging a salty chin, "it is just too risky with a black flag." The skipper took a deep breath. Pressure was taking its toll on our weary crew. A two-point lead was nothing in a 73-boat fleet. Each individual coped with the tension in a personal way Eye contact was universally avoided. The mid-crew made one more wisecrack. Nervous laughter broke the spell. "Jib up!" commanded the skipper.
Now with less than four minutes to go and a nearby collision the tension was almost unbearable. "There he is" the mid-crew pointed. They had been monitoring their closest competitor. The collision had momentarily distracted them so the rival had been lost in the mass of boats and sails swirling around the pin end. When they finally spotted them again our team was on starboard tack near the pin. The rival was on port tack coming towards them. The two boats were going to pass port to port. "If he tacks in behind us we will have to jibe. We can't let him pin us beyond the starting line", voiced the skipper. As the two boats came beam to beam the crews stared at each like gunfighters at a shoot out. Everyone wore masks of determined confidence, but they all felt the poison of self-doubt creeping into their core. No one looked away. The skippers studied each other's tiller. Time slowed to a crawl. Finally the rival skipper slid the tiller to leeward and started to tack. Instantly, without a word uttered, our team rolled into a jibe. The boats started to circle. The rivals fell off onto starboard as our team rounded up on port. They were still beam to beam. "It looks like he wants to dance", said the tactician with false confidence. "Are they following our jibe", demanded the skipper? The rival boat made a motion to jibe behind our heroes, but suddenly they were forced to brake off as an unaware contestant blocked their path. "Nice pick!" announced the tactician. The skipper breathed deep. Match racing a competitor during a crowded fleet start is difficult at best, and highly risky. With nothing to gain and everything to loose our team had no taste for this kind of high stakes knife fighting. "Three minutes" droned the middle crew with obvious relief.
As they sailed away from the pin on port toward the middle of the line the density of the fleet diminished. They kept a constant vigil for starboard tack surprizes. The skipper held high on the line. With the pin end so favored it would be difficult to start on starboard tack. They would have to tack onto port quickly after the start if they were going to have any hope of a clear lane. Since the wind was in a hard left oscillation any boat that jumped out to the right would gain when the wind finally shifted back, …IF it shifted back to the right. They had to find a way to tack at the start, or shortly thereafter. "Two thirty!" They tacked back to starboard and headed towards the pin. Now there was only enough time remaining for two or three maneuvers. The density of boats increased immediately. The skipper grew concerned about finding a place to tack back. With so many boats packed that tightly together it was hard to imagine enough room to swing a 180-degree turn! "Looking for a place to tack", the skipper shouted in an anxious tone. "Hold on…hold on… there! Behind number 17!" consoled the tactician. They were almost right at the pin before they found a void large enough to tack back onto port. "One fifty". A glance over the shoulder confirmed the skipper's fear. Their rival was following two boat lengths back also on port! For an instant both skippers locked eyes. Wild sound, water, and flashes of color distracted everyone else, but the two skippers froze eye to eye. It lasted only a fraction of a second, but there was a world of comprehension in that glance. Neither would soon forget the moment.
If the rival closed the distance between the boats then they could prevent our leaders from tacking back onto starboard. There were four possible escape routes. They could allow themselves to be chased down the line on port tack, and then try to tack into a hole precisely at the last possible moment. That was assuming they could find a whole exactly when they needed it. They would also be sailing away from the favored end. A second option was to peel them off on a pick. It had worked earlier, but it was still too soon to tack back onto starboard for the final approach. Third, they could sail dead downwind for a time and then try to guess the exact point to sail back upwind. This worked reasonably well in a two-boat match race, but the mass of boats swirling around this starting line made estimating the turn around point impossible. Another option was to go on the offense. A couple of quick maneuvers might mix things up.
Without a word our skipper waited for a gap in the starboard take parade, then jammed the tiller hard to leeward. It was a reaction rather than a conscious decision. Like a tennis pro returning a super-heated first serve, there was no time to contemplate all the options and associated risks. Years of experience and thousands of complicated starts had molded this reaction. The boat shot head to wind and dramatically slowed. The rival team was caught off guard. Still on port they were faced with either luffing to windward of our heroes, or quickly ducking. They were coming fast and there was no time to contemplate. They ducked to leeward and shot past our team. Suddenly the table had turned. The rival team was on the defense as both boats sped down the line on port tack, our leader in hot pursuit. "One thirty" droned the mid-crew. "Four lengths off the line", yelled the foredeck holding up four fingers. More and more boats were setting up on starboard tack for their final approach. Soon there would be no room to maneuver on port tack! The chase continued over and under increasingly dense packs of starboard boats. At one minute and ten seconds the rival team found just the right pick to shed their tail. They slammed a tack onto starboard behind a slow moving pack. "Let em go" shouted our tactician. The skipper had no intention of continuing the attack. They ducked the rival, but remained on port. The challenge now was to find a reasonable place to get back onto starboard. "Trim!" demanded the skipper. The jib came in tight as the boat came up to close hauled, still on port tack. They just barely crossed a number of slow moving starboard tack boats. The last one waved them across in order to preserve a narrow spot on the line. "Half a length" screamed the foredeck. The hectic pace sped up to unbearable proportions. Half a boat length to windward lay the demise of there fortunes. They were within one minute of the start and if any particle of their boat crossed that line... , they would have a long lonely sail back to the club. The black flag was snapping briskly from the committee boat's mast. To leeward lay the bristling bows of dozens of starboard tack boats. The skipper swallowed hard, a dry mouth, a pounding heart, and hands clenched tight around the tiller.
In less than 50 seconds the extreme tension would subside, but in the mean time our brave skipper struggled for composure. Maintaining a consistent level of adrenaline is essential to good judgment. Too much excitement warps the brain's ability to accurately perceive the passage of time. When we are frightened the perception of time slows. Anyone who has been through a life threatening experience can attest to the time warp leading up to and during the event. Pleasure has the opposite effect. Starting a sailboat depends, above all things, on the clarity of the human mind to be aware of time and distance. Our skipper knew all this, but knowing is different than feeling.
Still on port they made one more harry cross and then found a barely manageable gap to dive down into. "45 seconds", the mid-crew pounded. Suddenly there it was. A three-boat length hole in the luffing ranks of starboard tack boats. It wasn't just luck that it appeared before them. Our skipper knew that there would be sporadic gaps in the line, but patience had been wearing thin. Now a few lengths in front of them was bow number 71, luffing on starboard tack. They were holding up a dense group of boats very high and very slow. Our skipper aimed directly at 71's amidships. Number 71's skipper was unprepared to deal with this sudden threat so late in the game. At the last moment they bore off hard to prevent our team from stealing their coveted leeward hole. The two boats were bow to bow and closing fast. As soon as our team started to tack in order to avoid a collision number 71 shot back up head to wind. They were trying to generate distance between the two boats, and recapture a hole to leeward. It would have worked with a lesser competitor, but our skipper was too good. The moment number 71 started to head back up our skipper slowed the tack. They coasted head to wind for a moment and then fell off onto starboard less than a few feet to leeward of 71. "Thirty", screamed the mid-crew.
The noise rose to a deafening shudder as all seventy-three boats luffed their crisp new sails. The only communication available now was a full scream. The foredeck was completely out of range. They reverted to hand signals. A single finger held high meant that they were only one boat-length away from the line. "Full Luff", screamed the skipper. The jib luffed with unimaginable intensity. The hole they had to leeward was workable, but slim. "Twenty!" The tactician remained silent. It was all up to the skipper now. The largest hole, or the best position on the line, meant nothing if the skipper pulled the trigger at the wrong instant. The foredeck held up a bent finger, half a length. "Trim!", shouted the skipper, voice cracking at the severe limit of vocal cords. The jib came in tight, but it did not fill. The skipper was severely pinching high into the wind generating just enough forward motion to maintain steerage. Still too early to use the newly acquired gap to leeward, the skipper paused for a moment, every nerve strung tight, every sense alert.
It is hard to say what exactly clued the skipper into pulling the trigger. It might have been a signal from the bow. Or, it might have been an intuitive guess. Probably, it was a sense that boats on either side were starting to go. Ratchet blocks and spinning winches sometimes give warning, but there are too many cunning competitors who spin false clues. As the countdown pounded out the final few seconds the fordeck held up a fist. They were extremely close and they were nearing full speed.
Bang! The starting gun fired. "HIKE!" screamed the skipper. Everyone pushed hard on the windward rail. "Hang here for a few more seconds and then we can tack", said the tactician. The skipper glanced under the boom. A half dozen boats were bow out, and ahead, but no one could quite tack and cross yet. The boat immediately to leeward was too close. Eventually they would fall into bad air. "Won't last here long", groaned the skipper. "Just hang… a second longer… Now! Tack!" Without looking they tacked to port. Bow number 71 was close and still on starboard. At first glance it looked to the skipper that they wouldn't make it across her bow, but a second later in became clear that number 71 was moving too slow. Since the pin end was so favored if they could cross 71 they could cross everyone. They cleared by a half dozen inches. "Nice call", the skipper congratulated the tactician, right foot trembling with left over anxiety. "SHHHHHH! Listen to the VHF!" The radio began to chirp the bow numbers of boats that had been blacked flagged. Four boats had been identified. None of the top five were affected.
Our skipper felt the extreme pressure slowly drain away. In its place raw determination took root. The shear volume of critical decisions had been reduced, but this was just the start. They still had to slip their boat through the wind and rough seas faster than any other. That demanded an unnatural level of concentration. They slammed a few waves, healed a little too much then, over-flattened before the skipper zeroed in on the delicate groove. Our team began to function like a well-oiled machine. The foredeck kept a constant vigil for threats, and reported information back to the tactician. The mid-crew began counting down time to the puffs and describing the onslaught of waves, " puff in four, three, two, one… flat spot ahead…." The cockpit made constant micro adjustments to the jib, a little ease when the skipper put the bow down to power through waves, and then a firm trim as they coasted high into the wind during the flat spots. The tactician was uncharacteristically morose. "Good start, but you will never guess who won the pin?" The skipper didn't have to look. It had to be their rival. "Damn! Those guys are good."
At the start everyone who had been to leeward of our heroes had wanted to tack onto port, but no one could make a clean cross. Our team had been pinning everyone. So when they eventually tacked onto port they had opened the floodgate. At least a half dozen boats had tacked almost simultaneously. Four of them were now abeam and to weather. The windward most boat, the boat that had miraculously won the pin, was off to an early lead. It was going to be a long final race.
… to be continued …
Is My Sail Wrong? Or is
My Boat Out of Balance?
Response: Before you assume that your boat is not balanced properly you should be aware of some other factors that effect your rudder. In the wonderful world of sailboats nothing is as simple as it seems.
Rudder pressure is not nearly as important as rudder angle. The hinge point on your rudder has a dramatic impact on the pressure that you feel. A rudder that is not very deep, but is long fore and aft will create a lot of pressure if the hinge is along the leading edge. If the pivot point were further aft you would feel less pressure. Rudders that sweep aft also create more pressure but they don't pick up weeds as readily. Some rudders have a hinge that slants forward. Stars, Shields and most full keeled boats are good examples. When their rudders are turned hard some of the rudder's rotational force is lost because the forward slant of the hinge forces the rudder into more of a wedge. It begins to pull the stern down rather than to a side.
In order for boats to sail upwind their keels have to suffer some leeway. It is this leeway that allows the keel to create lift. A keel, or centerboard, flys to windward in much the same way an airplane wing does. It isn't easy to make a wing or keel fuller or flatter like we can with our sails, but we can add more curvature to a wing by dropping the flaps. The rudder on a sail boat acts very much like the flaps on an airplane. That is why most boats sail best with about 3 degrees of rudder angle. (Tiller pulled to windward, ... flaps down for maximum lift) The amount of leeway, speed, and balance of your boat will affect the optimal angle, but 3 degrees is a good starting point.
In heavy air keels or centerboards can create more lift than the boat has ballast. That is why raising your centerboard relieves some of the pressure. The Centerboard was providing too much lift relative to the amount of opposing pressure on your sails. That lift was trying to drive the bow into the wind and making the boat heel. You were countering with your rudder.
When a boat heels too much many things start to act on the rudder. The keel will stick out to windward and the mast and sails will go to leeward. This creates a kind of torque on the boat. The drag on the keel wants to push the windward side of the boat aft and the sail plan wants to drive the leeward side forward. Think of it as if you were dragging your leg in the water. The boat will want to turn around your leg. Once the boat is heeled the rudder becomes less efficient. Rudders are generally designed to rotate the stern of your boat back and forth within a plane perpendicular to the rudder. This works relatively well when the boat is standing upright, but when it is heeled some of the rotational force wants to push the bow up or down rather than sideways. Maybe this accounts for some of the forward slanting rudder hinges ?
Another thing that occurs when a boat heels is that the leeward chine (the bottom corner) of the hull is pushed further to leeward. The wider the boat the greater the effect. If you have ever sailed a Lightning (a relatively wide boat with a "hard chine") you would have found that the helm is greatly affected whenever the leeward chine is dipped into the water. Lightnings actually use their chines to create some lateral resistance. When the chine hits the water it acts like a bent ski. The boat wants to follow the curve that the chine makes as it curves from bow to beam. Lightning sailors quickly learn that there is a critical heel needed to sail well upwind. The hard chines and flat bottom of a Lightning make the boat very fast downwind in planing conditions, but they can be very challenging if you happen to dip a chine at high speed. At the extreme range of control the boat gets bounced form chine to chine in wild oscillations just before the crew gets wet!
It is probable that your sail plan isn't perfectly balanced with your keel and rudder, (they seldom are) but be careful to avoid over simplifying the equation. Make sure the boat is sailed flat and in many different conditions before you assume that an alteration in your sails will solve the performance problem. You might try to experiment with your headstay length, or sail controls first. Try making the mainsail flatter and feathering the boat harder when you feel too much helm. If you are still convinced that you have a balance problem give me a ring next spring and we will go for a sail. There isn't much I can determine by examining a sail on my loft floor. Beware of sailmakers who claim they can.
Our BIG Chicago Mac
We corrected over the boats that had finished but who knows what 30 something with a 260 PHRF rating slumbers in and corrects out on you. To our
surprise the wind totally shut off for about the next 16 hours and we were
victorious!! And, not just victorious, but we won by more than one hour
Luck. We happened to be situated up the Michigan shoreline almost perfectly placed for the big shift to the Easterly quadrant.
Boat. The J/125 is a powerful, 41-footer that is easy to shift gears (for a ULDB). While the first part of the race was not what I thought favorable for us (75 miles upwind), we still hung on and the boat with the Cuben Fiber Heavy #1 seemed to drive through the waves well. The A-spinnaker flying was particularly good for the boat and it represented the majority of the race.
Boat Set Up. Beside a few minor changes, Raincloud is set up as it comes from
the factory. An easy boat to sail allows you more time to do the things that win races. Mike Rose spends effort and money in areas that make the boat fast
without throwing money aimlessly.
Is light air stimulating?
I don't find light air all that stimulating. It is hard to get enthusiastic about endless hours of tedious concentration and unbearable discomfort. The only saving grace is that there are skills involved... most of the time. The frustrating thing about light air is that the wind can change much faster and further away than you have the means to react to it. Even though you may be the first boat to see a developing puff way off in the distance you are usually traveling at such a slow rate of speed that there is nothing you can do about it. A long-range strategic plan is critical for light air success. Paying attention to weather patterns, or being tuned in to geographical or local factors pays huge dividends in light air.
What’s different about light air?
The first thing you might notice about light air sailing is that tacking and gibing angles are extremely wide. Why? We will get to that a little later. The important thing is that wide angles impact your game. Take the start, for example. When you are sailing very low angles you are pointing fairly close to the leeward boat's windward quarter. The lower a boat points the greater the distance you need to leeward in order to avoid being pinched off. This has the effect of making the starting line appear shorter than it actually is. Boats that start in the middle of the line usually have to sail much slower because they have to "pinch or die". The boat that wins the pin, or the boat that tacks off at the boat, can crush the performance of the mid-line boats. That is why some boats in light air gain a huge lead very quickly. They can perform optimally while the rest of the fleet has to wait until a lane dominoes open on port tack. Sometimes the entire front row will end up on port tack shortly after the start. This happens because no one can make starboard tack "stick". The only good starts are those boats that are able to tack and cross, and the boat that wins the pin.
Some sailing scholars attribute the "picket fence" theory as the reason why boats at either end of the line make initial gains. The theory suggests that a crowded starting line acts like a snow fence and the breeze lifts up over the fleet allowing the boats that start at the ends to squirt. There may be some truth to it, but it is a very old theory and I think there is some room for more practical thinking. Whatever the theory, the middle of the line is usually not a good choice in light air. I hope only my friends and relatives take notice because as word gets out the price of seating gets proportionally higher as you approach the ends. I wouldn't want to do anything to inflate the price. It is already crowded at the ends so don't tell anyone else.
Hull speed in light air
Many people have heard the term "hull speed", but few people really know what it means, or why it is important. I am sure I don't fully understand all the connotations, but this is the way I comprehend it. Imagine you are standing on a motor boat holding onto a towline attached to a J 24. The motor boat accelerates to 1 knot. Let's say the pressure on the towline is about 25 pounds. You can still hold onto it. Now the motor boat accelerates to double the speed. You are now moving at 2 knots. The load on the towline increases to about 80 pounds. That is more than twice the load, even though the motor boat has only doubled the speed. Now the motor boat accelerates to 4 knots. By now you will have developed a new respect for the guy who usually hangs onto your spinnaker sheet in heavy air. The load on the towline has increased exponentially! Eventually something weird happens when the boat starts to plane, (by now I hope you have let go) but this article is about light air so that doesn't concern us here. The bottom line is that it takes more and more energy to increase a boat's speed the faster it is going. So in light air it only takes a very small increase in wind to double a boat's performance. If you think about it you have probably noticed that in light air the first boat to get to a puff can sometimes double or triple the speed of any other boat. That just doesn't happen in heavier air. A big puff in heavy or moderate air will only increase your speed by a few tenths of a knot.
This is why the angles get so wide in light air. Even though it may seem that you are moving very slowly you are actually moving very efficiently relative to the wind speed. A J 24 might have 2 knots of boat speed in 5 knots of wind. It doesn't take a lot of energy to push a J 24 up to 2 knots. The faster a boat travels relative to the wind the further forward the apparent wind gets. As the apparent wind moves forward, your tell tails lift and you have to bear off. Hence the wide angles.
On the other extreme a J 24 might have 4.5 knots of boat speed in 20 knots of wind. It takes a huge increase in energy to make a J 24 accelerate from 4 to 4.5 knots. This lack of efficiency means that the J 24 can not move fast enough to drag the apparent wind forward. The result is that in 20 knots of wind the boat points extremely high.
Remember that the next time an Etchells sailor brags about how high his boat points. One of the reasons his boat points so high is because it is so slow! It is a relative thing. America's cup class yachts sail at very disappointing angles because they are so fast.
Interesting topic, but not very useful.
Puffs or shifts?
If you understand that concept then it should be easy to understand why the puffs are more important than the shifts in light air. Who cares if you pick up a small shift compared to the possibility of going three times faster than any other boat! I will happily sail in headers all day if I can go that much faster. The same applies to clear air. There is a much higher cost to sailing in bad air when the wind is light. It is also more difficult to find clear air when the breeze is failing. Wider angles mean fewer available lanes.
Light air downwind jibing angles are wide for the same reasons sited above. As the fleet spreads out downwind it is tough for the leaders to find a clear lane. They usually have to accept huge risks, sailing way out towards the lay lines in order to maximize clear air. This makes them vulnerable to small puffs. Even very small puffs can enable you to sail much lower downwind angles. It is common for people to get caught overstood, or to be passed by numerous boats on the opposite side of the racecourse.
Another interesting point about racing in light air is that the wide angles reduce the effect of wind shifts. The higher a boat points the more important it is to stay in phase with the wind shifts. The wider the angle the less gain or loss in a shift. The result is that it is often better to sail through a shift in light air rather than tack twice. This in turn increases the risk factor because tacking fewer times means sailing closer to the lay lines.
Finally, light air usually comes with flat water. This makes driving relatively easy. A higher percentage of the fleet will perform well. Talented drivers can't rely on superior speed to get them out of difficult situations.
Only one boat can win any given race. The numerous factors that determine the winner are beyond human comprehension, but developing your knowledge and skill will help you get lucky.
I like to visualize the negative characteristics of stretch in two distinct ways. First, stretch absorbs energy that could otherwise be directed toward producing speed. This is a good theory but it is difficult to get a tangible feel for it. Bicycle racers are always trying to develop the stiffest frames so that they will transmit as much energy as possible from legs to wheels. If the frame flexes, some of that energy is lost. Likewise, sailors are always trying to turn the energy of the wind into speed. If the sail, halyard ,mast or sheet stretches, then something is wasted. Second, stretch allows things to change shape. Sailboats are highly dependent on specific shapes in order to function properly. Therefore, shape changes are extremely important.
It is especially critical when a sail changes shape. Usually stretch means that the sail gets deeper and the draft position migrates aft. This is exactly opposite the effect that we desire when the wind increases. Ideally the objective is to flatten the sail and hold the draft forward, but until someone invents that elusive "reverse shock cord," we will have to cope with a certain amount of stretch as the wind builds. (A reverse shock cord would be a shock cord where the harder you pull on it, the shorter it gets. Let me know if you find one. I have a couple of great applications.)
But not all stretch is bad. We can compensate for the increased depth and the draft-aft position-change by using our sail controls. We can flatten the sails by bending the mast, tightening the headstay, pulling the outhaul and moving the genoa lead aft. We can then pull the draft back into place by pulling the cunningham or increasing the halyard tension. These controls work because the sail membrane stretches. Sometimes stretch can act to automatically depower the sails by allowing the leach to twist open. I like to refer to this as a "lively sail" or a sail that "self corrects." These sails are very easy to trim because they require less concentration on the part of the crew. They are especially fast off the starting line when the crew's attention is often occupied elsewhere.
Most sailmakers incorporate the use of a "tack spike" in their genoa panel layouts. A tack spike is an inverted "V" of stronger material connecting the tack to the clew. In theory, the "V" spreads open when the lead is moved aft and the foot is stretched around the chainplates. As the foot is stretched, the middle portion of the sail is then effectively flattened. Another useful function of stretch is on boats that have a wide range of mast bend such as a Melges 24, Star, IC dinghy, Finn, Laser, Europe, and just about every kind of boat with a free-standing rig or a bendy spar. Low-tech cross-cut Dacron mainsails usually work well in these applications because the sail's elasticity absorbs much of the excessive mast bend.
So do you want stretchy sails or don't you? And why are so many high-tech, low-stretch sail materials available? If stretch is so bad, why doesn't everyone use the lowest stretch material available? The answers are clouded because every boat, mast, and sailing condition has a corresponding "appropriate stretch." Sailmakers and sailcloth suppliers hate to talk about this aspect of their products because it is virtually impossible to quantify, and if they have trouble quantifying how stretch interacts with sails, how can they predict the results? Complex computer modeling programs are designed to try to predict loads within sails, and the cloth suppliers have lots of fancy graphs displaying breaking strengths and elongation. But the ugly truth of the matter is that getting the appropriate stretch to fit your application is completely dependent on the experience of your sailmaker. This is because sail loads are dynamic, threadlines vary throughout the sail, new materials reach the market at a surprising rate, and sail geometry's too numerous to count.
Weight. Lighter sails are better than heavier sails, but lighter sails of similar materials will stretch more. Scientists use the term modulus when they describe stretch-to-weight ratios. The higher the modulus, the lower the stretch. Many larger boats require very high-modulus fabrics to handle the severe loads they generate. This has led to many exciting developments in sailcloth. Most of us understand that weight aloft increases the healing moment and pitching so lighter sails are preferred, but more important, sailmakers have become accustomed to adjusting the stretch characteristics of their sails by varying the fabric weights. They also have to make sure the material does not have a catastrophic failure, so higher loads might require heavier material.
Adjustability. As we have seen, some stretch is good, but too much is bad. If the sail is not sensitive to the sail controls (i.e., mast bend, cunningham and outhaul), the sail is probably stretching beyond your means of controlling the sail shape. In this case the sail is "underbuilt." The sail may appear too deep, and no amount of mast bend or headstay tension will flatten it. Or the leech may blow open and no amount of sheet or vang will correct it. Conversely, if the sail is "overbuilt," the sail will be too sensitive to the controls and it will be virtually impossible to efficiently change the shape as the conditions change. It will not "self correct" for minor wind changes. An example might be a mainsail so affected by easing the backstay a small amount that the draft jumps way too far forward and the cunningham cannot be eased fast enough, or a headsail that is so sensitive to halyard tension that you never seem to have it set just right. Neither sail will have a sweet spot.
Orientation. The direction of stretch affects the sail shape. The size, tension, and direction of fibers within the fabric varies. Since fabrics can be arranged in an infinite array of orientations, sailmakers have found that they can adjust the stretch characteristics of sails by changing the fabric orientation. Threadline orientation is an amazingly complex topic and deserves more attention than I can afford in this article, but in general a sail built with too much stretch vertically and not enough horizontally will become too flat too quickly. Conversely, a sail with too little stretch vertically and too much stretch horizontally will tend to get too deep.
Longevity. Finally, stretch is only "good" when the sail material will return to its, original shape when the loads are reduced. We call this property of stretch memory. Memory is extremely important to the value of a sail. A sail material that has more memory will last longer because the sail will return closer to its design-shape after many cycles of stretch. Unfortunately, many of the very high-modulus materials have very little memory. Quite often the fastest sails are those that are light, or stretchy enough to be lively, "self-adjusting," and responsive to sail controls' "memory." The bad news is that these qualities can deteriorate quickly as the fabric breaks down and loses its memory. Nowhere is this more obvious than in one-design classes that legislate woven Dacron with no minimum cloth weights. In these classes, sails and especially jibs become truly disposable with a life span of no more than one or two regattas. Sailors are therefore always choosing between the better performance of a lighter, stretchier fabric with a lot of initial memory versus the longer life of a heavier, less stretchy fabric.
These considerations affect all sailboats to a greater or lesser degree. In some cases you do not have any control over these variables, but for most of us, knowing how stretch affects performance is the first step toward improving our knowledge and eventually our results.
The bottom line is that stretch is not an evil word. If you learn to tame It, you might find that you can put it to good use.
Starting sailboat races has to be the weakest aspect of our game. Until we deem it necessary to pay for some new technology to police us we will continue to suffer from the inequities of starting. The following are some of my personal experiences and some stories I have heard concerning the unfairness of starts.
When ever you enter a "starting discussion" someone always brings up the concept of a "rabbit starts". In this format a rabbit sails up wind on port tack and the fleet ducks the rabbit on starboard and thus starts the race. In theory it sounds good. The fleet never has to deal with a general recalls or the endless hours of redress hearings, but there are some inherent problems. The biggest being that some boats start racing well before the last boat starts. So if the rabbit is fast you would rather duck him last rather than first.... I have heard of a few times where the rabbit was not very fast and a clever starter was able to duck first then quickly tack and then proceed to roll the rabbit! A few years ago at the J/24 East Coast Championships with 90 plus boat attending we experimented with a rabbit start. In this case the rabbit was tailed by a small outboard so that when the rabbit tacked it would give her a fair start with the fleet. The rest of the fleet was supposed to duck the power boat. Most did, but someone misjudged the duck and sunk the rabbit. The rabbit died and we sailed the rest of the regatta with conventional starts. It only takes one bad apple...
Lately is has become increasing popular to request redress when you are scored OCS. At first I found this extremely distasteful until it was me who found alphabet next to my name. On a whim and a prayer I filled out the appropriate form and waited for my turn in "the room". At least five contestants preceded me, every one willing to take a lie detector to prove that they were not over early . One by one they left "the room" with down turned eyes and a disgusted expression. As my time neared, I became less optimistic and a little embarrassed. When I finally entered "the room" and I saw the tired, but stern faces of the jury I was willing to drop the whole thing. They sat me down and pushed "play" on the tape recorder. In the background I could hear someone counting down the time every five seconds. In the foreground I could hear another voice calling bow numbers of boats that were over early. I guess a third person was writing down the number of those poor unfortunates like me. In the middle of the tape I heard my number clearly, .."30!". 30 was my number. I apologized and started to stand up when one of the jury members sat me down with a stern look and a finger to his lips. They made me listen for another half minute. Was this some sort of public humiliation? Was I to endure this as a punishment for wasting their time? I hadn't felt like that since high school detention, which I am sorry to admit I was all too familiar with. When the tape ended shortly after the bang of the starting gun I was told to step outside. Then came the real torture. They made me wait outside that room for quite some time with all the other "condemned", while all the "good" sailors enjoyed free beverages at the bar. Just when I could not stand it any longer I was granted another audience with the jury. This time they had smiles on their faces. When they replayed the tape for me, one of the jury started his watch at precisely the moment they called my number. When we heard the sound of the gun the tape was stopped and all eyes turned toward the gentleman with the watch. "Exactly 30" he commented with a grin and a wink. As we listened to the tape three of four more times it became apparent to us all that the person calling out the time in the background felt that the 30 second mark was more significant than the 35 or the 25 mark, so much so that he used a louder voice to commemorate the occasion. The foreground voice never uttered my number, but the person writing down the OCS's recorded number 30. I learned two valuable lessons that day. Never be shy about asking for redress, and try to avoid bow numbers ending in a zero.
Just last Sunday I was racing my Laser in a windy frostbiting race. I won the first two races, but my lack of physical conditioning was beginning to show . The start of the third race was very crowded at the boat end. I got off fairly clean but there was a rather large healthy looking lad just under my lee bow. I could hear him grunt as he hiked and torqued his boat increasingly closer to my leeward rail. Just when it seem inevitable that I was going to need oxygen. I heard a voice from the committee boat. "631 and 989 over early...... 989....989 your over early too!" I looked up at my sail number 691 with relief. Then the boat under my lee boat bore off and headed back to the starting line. I got a quick glance at his sail as he jibed around, a single digit "2". I chuckled to myself remembering "989 your over early ...too!" The humor was soon lost as the pain returned to my legs. I don't think anyone else ever realized the truth of the matter...
Recently at the J/24 East Coast Championships with 80 boats competing the first race was started without a general recall. Twenty or so boats were observed to be over early. They listed all twenty boats over the radio. Including a midline boat there were three different positions from which the transmissions had to come . By the time the last boat was called back almost two full minutes had elapsed. The more I thought about it this seemed unfair. With a large number of boats being recalled there was a very good chance of making a reasonable comeback, however there was an obvious disparity between the most flagrant violator, who was called back immediately, and the poor guy...me, who was closest to starting clean, but was the last boat called... two minutes later. To make things even more unfair I was destroying the poor guy who sailed in my bad air for two full minutes. Upon questioning the committee after the race they seemed to feel that it was necessary to "send a message" that they were out to get OCS's. There were no throw outs, and later in the regatta there were plenty of general recalls. Maybe I am the wrong person to point this out but it seems to me that their message was rather pointless, It only served to add an additional measure of randomness into the results.
To my way of thinking the race committee priorities should be three fold. First, the race committee has to be impartial. They should do everything in their power to make the race a fair test of skill despite local favorites, or ugly histories. Second they should do everything they can to reduce the randomness. Ie keep the line square, abandon races that are drifters or fetches, etc. Finally they should get as much racing in as they possibly can.
Sometimes the third and second priority conflict. I would personally like to sail one less race to insure my skill is tested rather than flip a coin to see who wins the extra race.
Calling people back on the radio is a great way to prevent the "loudest silence" and to free up air for those who did not get a head start at the gun. But I find it hard to justify calling large numbers of boats over early because it takes too long to call them all back within a reasonable time frame, and it ruins the races for many who are not over. It also increases the likelihood that a few lucky stiffs will get away with an unskilled jump on the fleet. Hiding is a skill, but there is always a random risk involved. Sometimes an aggressive fleet and an uncooperative tide will make it difficult to get a race started and I am very sympathetic to the plight of race committee. In this case the second and third priorities merge. Most competitors would rather race than practice starts all day. Every one will then expect, and tolerate a higher degree of randomness.
Race committee work is difficult. Far be it for me to complain about the wonderful people who volunteer their time to start sailboat races, so if I offend anyone I sincerely apologize. This is still the greatest game on earth.
50.1 Changing Sails
The jury decided that this rule did not preclude using two headsails on the same foil.
Why should it be illegal anyway? Well it turns out that some years ago Ted Turner had two genoas of maximum size built for one of his boats. One sail was designed as a low cut deck sweeper, and the other, a high clewed sail that lead to the aft quarter. Both sails were of maximum allowable size, and similar in actual sail area. However, If both sails were set on the same side one inside the other than the sailing area was significantly expanded. (I guess you don't become a billionaire be being stupid, or by being uncontroversial). Eventually, they made some rules against that, but sometimes history repeats itself.
The problem with writing anything meaningful about headsails is that they come in so many shapes and sizes. There are, however, some universal concepts that you should understand.
Size and Profile
We could design multiple sails that measure 150% but with varying leech and foot lengths. A good way to visualize this is an imaginary line parallel to the headstay, but 150% aft from the headstay. A 150% genoa has to have its clew fall somewhere on this line. The position on this line influences the fairlead position. Too low, and the sail will hit the fairlead before the top can be sheeted in. Too high, and the sail will not seal properly on the deck, or it could sheet off the aft end of the genoa track.
Some genoas are designed with a relatively high clew, while others are low cut deck sweepers. Why such a spectrum? To begin with, a high clew provides better visibility for cruising applications, but a "deck sweeper" increases upwind performance. This is because sails work by creating differential pressure on either side. Letting air slip under the bottom of the sail makes it harder to maintain the pressure difference.
Many one design and handicap rules do not restrict foot roach, or they are generous in this regard. If foot roach is an unmeasured area then it may be possible to design a genoa with more sail area by shortening the leech. This works well in light air sails because the raised clew allows for the extra area off the deck to be filled with "unmeasured" foot roach. It also makes the sail wider, higher up. In higher wind, however, this unsupported foot roach may flutter, flap or fold over. The extra area higher up may add to back winding the mainsail, so it makes sense to have the heavier air genoas lower clewed.
Another often overlooked consideration is that the lower the clew, the lower the area in the sail that is affected by fairlead position. That means lower cut genoas have a narrower wind range than higher cut sails. They also tack slower! Since the top of the sail is the last portion of the sail to be trimmed after a tack, the higher the clew the quicker the top of the sail comes in.
Reaching genoas have very high clews for a few reasons; the top of the sail needs to be adjusted quickly for a wide range of apparent wind angles, the foot of the sail has to be raised above the wave action when the boat is heeled over, and sheeting the sail from the aft quarter allows the foot of the reacher to be further away form the mainsail.
However, finding the exact depth that is optimum for your genoa on your boat in any given condition, is an art that can only be accomplished through human intuition, observation and experimentation. Some neophytes believe that sailmakers have sophisticated machines that they plug a few numbers into and presto, out pops the perfect molded sail for your application. Reality is never so glamorous, or as profitable. Every boat exhibits different balance characteristics. The amount of draft built into any of the sails influences that balance. Sailmakers have to rely on a level of experience to optimize the volume of shape built into any particular application. Luckily, sails are flexible, so much of the adjusting can be done with sail controls.
The best genoa shapes are the ones that perform well over the widest range of conditions. For example, J/24s are allowed only one genoa and one blade jib. The genoa has to function in winds from 0-20 knots. Since most racing takes place in winds 8-12, you have to be fast in those conditions, and you have to win the occasional drifter and the occasional 18-20 gear buster. Occasionally, a sailmaker shows up with a genoa that is flatter or fuller than the norm. They usually do well at one end of the spectrum, but they suffer the rest of the time.
Creating a genoa that has a wide sweet spot is much more difficult than creating one that works well in a specific condition. There are only two ways to build depth into a jib or genoa. One is by adding curvature to the parts of the sail as it is assembled. We call this internal shaping. The other is by pushing shape into the front of the sail by adjusting the luff curve. We call this external shaping. Usually a combination of both methods are used, however the relationship between internal and external shape has a huge impact on how the sail reacts to sail controls. For example, let's suppose I design two genoas. Both genoas are to be 22% of the horizontal cord length deep, and maximum draft position is 33% aft from the luff. One genoa uses more internal shape (sail "IS") but less luff curve. The other sail is relatively flat internally (sail "ES") but has more luff curve. Both sails might look and perform exactly the same until the backstay, halyard, or lead position is adjusted.
Sail "ES" has more external shape so sagging the headstay is more likely to create a knuckle in the luff requiring too little halyard tension in an attempt to push the draft aft.
Sail "IS" will absorb more headstay sag and get deeper as a result. But, if the headstay were tightened it would get flatter in the luff requiring too much halyard tension while trying to pull the draft forward. It might even start to turn inside out like "overbend wrinkles" on a mainsail that has too much mast bend.
Using the same example, but leaving the headstay the same the two sails will behave differently when the jib lead is adjusted. Sail "IS" will require a wider fairlead range because the fabric in sail "IS" will have to stretch before the lower sections are flattened. Sail "ES's" lower draft will flatten quicker with less lead change, but the lower draft position will shift aft just as fast.
Good luck, and be good to your crew.
What about paneled sails versus 3DL?
Wild claims have been made drowning the truth in self-serving sales hype. The following is my perspective and mine only. It may be self-serving, but I have tried to be as open-minded as possible. If you have anything to add, or if you find flaws in my logic, let me know.
Plenty of top handicapped boats use 3DL sails. Plenty of successful the successful top handicapped boats use paneled sails. Just about every medium-sized sail loft can point to a fast boat as an example of their "superior" technology. Maybe its all marketing hype, or maybe there are some small differences, but it is very hard to determine which technology is better, based on handicapped race results. When you compare Kevlar, to Polyester, a huge and obvious difference exists. But once you try to determine which use of fiber and Mylar is better, it gets confusing. The chief claim to success is that their system is lighter and more durable. What happened to getting the sail shape right?
I honestly do not know which system is better. I do not sell 3DL or Tape Drive products, so I obviously hope that there is no advantage. I do not see any science that proves anything either way. I have heard all the technical claims. I have seen all the glossy sales literature. They sell a lot of sails, but does that prove that they are better, or does that mean they are spending more money on marketing?
If I were to conduct a test to settle my own curiosity, I would probably select two one-design boats. I would find crews of similar skill levels, and I would make sure that the sail shapes and weights were as close as possible. Then I would go sailing, switch crews, switch sails, and test them in every possible condition. I would also test them over time to see which sails stayed faster longer. It would take some time and a fair amount of resources, but wouldn't that be the absolute definitive test of which product works best?
So here's the rub... isn't that exactly what is happening in offshore one-design classes all over the world? If there is a way to make a boat faster under the governing class rules, believe me; someone will try to make money selling whatever it is. One-design sailors will spend ridiculous amounts to be just slightly faster. So where are all the 3DL one-design sails? They are not winning Mumm 30 events. They are not winning Melges 24 events. They are not winning J/24 events. They are not winning J105 events. All these classes have had 3DL and tape drive introduced into their classes, but they are not winning. In fact, I can only think of one or two classes where a 3DL sail is even perceived as a competitive option. If 3DL sails are faster, than why haven't they dominated the offshore one-design market? If they really do have a superior product, why do they have so much competition? Why don't they just go out and win every major championship and put all the other sail lofts out of business?
Let's take the Mumm 30 class for example. The Mumm 30 class is evolving at a very fast rate. The pros are constantly finding breakthroughs in tuning and in sail shape. Eventually the rate of these breakthroughs will diminish as people learn to optimize their boats to the limits of the class rules, but right now every regatta debuts some new little "trick". In one-design sailing, people buy whatever is winning. Sophisticated marketing schemes have less of an impact when the boats are the same. When the Mumm 30 first evolved, a large percentage of the fleet had 3DL sails. Now, no one in the top of the fleet even considers 3DL, including the North salespeople! Maybe the reason is that the additional price doesn't justify the performance, or maybe the shape changes are happening faster than can be adapted to 3DL production. Or maybe, just maybe, they just are not competitive because they stretch too much. Whatever the reason, 3DL sails are perceived to be unacceptable in the newest, hottest, most successful one-design classes. It is similar story with all the other one-design classes.
Enough said. I am sure there are counter arguments. My opinion is that it is all just fibers and plastic. If you get the shape right that's 99% of the battle.
Oh, and I almost forgot...you still have to trim them properly!
There is a new product that is not just fibers and plastic that may be the fastest and best sail material available. Cuben Fiber Corporation is making custom sail fabric panels that represent a radical departure from anything we have seen before. But first...the history of the world according to Geoff Moore.
Humans started with wool. Cotton must have been a major advance. Egyptian cotton was better because the fibers were longer, and straighter. Remember that, the "fibers were longer and straighter". Eventually even longer and straighter fibers were synthesized. Enter Rayon, then Nylon then Dacron. Each advance meant longer and straighter molecular chains...fibers! All these fibers were spun into yarns just like the ancient spinning wheels used to spin cotton or wool. They start with fuzz pinch a corner and start spinning. Even Kevlar and PBO are spun, but I am jumping ahead.
The next advance after Dacron was the introduction of a resin pressed into the weave. These resin coatings locked in place the woven grid of fibers. This reduced both "bias" stretch and porosity, But heavy coatings of resin are temporary, at best, and they make the sail very brittle so they tear easily. Enter Mylar, a cheap readily available film that is equally strong in every direction. Laminated to a woven material, Mylar does a better job reducing bias stretch and porosity than resin coatings. Then came the aramid fibers, Kevlar, Technora, Vectran. These fibers are so strong they virtually do not move. The next advance was to hold the Kevlar yarn straight rather than weave it over and under each other. The straightness of the yarn further reduced stretch.
Today's Kevlar, Technora, and PBO are all made the same way. The yarns are held as straight as possible to reduce "crimp" stretch. 3DL material tries to do the same thing, but much larger spun yarns must be used. Once the yarn is held perfectly straight, the only "crimp" left is the actual helical spin within the yarn itself. Since it is impossible to spin a yarn with absolute perfection, some fibers within the yarn will be tensioned more than others. So the bigger the yarn the more likely to have fibers that are not being loaded. Unloaded fibers do nothing but add weight.
Somewhere along the way, Spectra was introduced. It was relatively inexpensive and it looked very promising, but if held under load over a period of time the Spectra fiber will slowly elongate, or "creep".
That brings us up to date. Next?....Cuben Fiber!
Here is where my primitive understanding gets a little clouded. Cuben Fiber is a Spectra-like fiber that is specially treated to make them stickier, therefore eliminating "creep"(creep is the result of microscopic slipping between fibers). Instead of being spun, it is "combed" through some special matrix. Somehow the film that contains the substance is then vulcanized into the whole matrix. The process involves autoclaving, which limits the panels to 30 feet.
Everything we have heard and seen about this product is "amazing". Imaging a genoa for a 40 footer that is the same weight as your current .75 oz. spinnaker! Imagine a Cuben fibre spinnaker!
There comes a moment in every race where future events seem to hinge. Sometimes it is a good start, or maybe a bad spinnaker set, but you can always find at least one turning point in every race. This was just such a moment. As they got closer and closer to the mark the helmsperson did a good job of keeping momentum, but he had to do so at the expense of steering low of the mark. Just when it looked as though they were going to have enough speed to make it, the tactician, suddenly shouted out "Shoot up"!
Now, in another circumstance his choice of words might have had the desired effect. In this particular case, however, the dutiful crew had been severely reprimanded, as recently as the pervious race, for not promptly following orders.
I can describe what happened next because I was on board the first starboard tacker that came into contact with this very unlucky boat. They came head to wind with no way on, their spinnaker at full hoist and beginning to fill directly behind them. As they lost steerage they fell off onto port tack, upon which they became a speed bump for the starboard tack line up.
It would appear that "Chute up" and "Shoot up" sound exceptionally similar. I can therefore find little fault with the crew that had been trained not to use their own natural intelligence, but to rely upon the commands issued to them by those of superior influence.
I may have embellished this tale a little but it does make the point that on well-crewed boats team members have a common understanding of why and when they should perform their tasks. I knew people in college who had tremendous difficulty because they tried to memorize every detail of their text book. To my way of thinking that is a much harder task than learning the concept of why the details are important. Once the concept is understood everything falls into place.
For example, I was planning to race an evening race on a J/24 this summer when one of my usual crew members called to cancel. I was then forced to pick up an eager non-J/24 sailor who happen to be on the dock. I had a total of eight minutes to teach him everything I have learned in twenty years of J/24 racing. So I decided to focus on the one command I was fairly certain he would not be familiar with. Sometimes at tight windward marks we do not have time to put the spinnaker pole up right away, or, as we approach the leeward mark we sometimes take the pole off early. Whenever we do either of these things our command is "human pole" at which our fifth crew member stands at the shrouds and holds the guy out at arms length and acts as a temporary spinnaker pole. This being a rather important, albeit unskilled task, and me having little time to educate, I proceeded to demonstrate exactly what I expected of him.
We were on port tack sailing to the starting area under spinnaker. I had the pole removed and then I stood on the port side and acted out the function of "human pole". When I saw the glint of understanding in his eye we dropped the spinnaker and made ready for the upcoming race. There was, however at least one fatal flaw in my three minute dissertation about the "human pole".
We were second to the windward mark, but it was a very close race and there was not enough time on the starboard tack layline to get the pole up. The drill was a "bear away set" onto a starboard tack reach. So I gained eye contact with our new crew and shouted "human pole after we round". He gave me the thumbs up and a smile. I felt reassured.
It took me at least half the next leg to understand why this seemingly nice guy was so determined sabotage our good performance. When we bore off around the mark he jumped immediately to leeward (port side) and proceeded to engage my spinnaker trimmer in a tug-o-war over the ownership of my spinnaker sheet. In the mean time no-one was acting the part of the "human pole" so our spinnaker was reluctant to fill. I am not sure how it came to me, but sometime after the shouting died away I began to understand that I had failed to express the concept that the human pole could be performed on either side of the boat depending on what jibe we were on.
Making sure the whole crew feels important and taking the time to teach them the reasons for their tasks is tedious and often frustrating, but it has huge rewards.
Last weekend my crew and I were at the Frigid Digit regatta in Annapolis. Unlike most of this summer, the conditions were puffy and shifty. We have always enjoyed sailing in this technically challenging condition. The following is how we like to approach this challenge while sailing upwind. Let's break it into three parts.
We like to set our controls for the lulls. The backstay has to be snug enough to hold the headstay reasonably tight if the main has to be eased quickly, however it should not be so tight as to depower the sail plan in the lulls. We also make sure that the vang is loose before the start. That way we can always stop the boat quickly during pre-start maneuvering. My forward crew then tightens the vang as we head up to start. We believe that it is better to come off the line with full power, even if the start happens to be in the middle of a big puff. During the big puffs we can react quickly by hiking harder or even sheeting out a little.
Once we have decided how things should be set up we try hard to put it out of our minds. That allows us to concentrate on getting a good start and making good decisions thereafter. The priority is to sail smart first, then make the necessary sail adjustments.
We have a schedule of things we do to depower, and power up. To depower we first hike out harder as the puff hits. We then ease the mainsheet if we have to. The next step is to lower the traveler, pull on the backstay, and then retrim the mainsail. We practice these steps so that we can effectively execute them as quickly as possible. When the puff diminishes we power up by, pulling up the traveler, then easing the backstay, and then readjusting the mainsheet to insure proper leech twist. The bridle is a course adjustment.
Ideally the mainsheet should be two-blocked at all times, but in the puffs when there is plenty of backstay on you will need extra main trim. Lowering the bridle insures that you always have enough mainsheet to trim, and allows the boom to slide further to leeward. In big lulls we ease the bridal, but are careful to lower it well before the next puff arrives. It is better to have it slightly too low than too high.
Please feel free to send us comments, or call me directly with any questions or personal experiences. Our thanks go to David Sprague for the use of this photo of a Lightning. Tim Healy 401-849-7700.
What is new in sail design?
The first significant change in 30 years to the design of the whole sail’s shape results in substantially reduced vertical curvature (known as minimal vertical curvature [MVC]) in your main and jib. You know how draft stripes show horizontal curvature in your sail. Vertical curvature could be shown by a vertical draft stripe from the head apex to the middle of the foot of a sail.
Design theory applied to win the America’s Cup in 1992 has spread from the top of the sport through off-shore and gran prix boats and even through our Olympic classes. It has finally made its way to the sails used by most one-design sailors. Today, sailmakers are using molded computer designs which interface with laser cutting equipment to build most sails, including your Lightning sails. Long gone are the days when sailmakers laid cloth on the floor and cut sail panels.
These new sails look different. They have straighter vertical curvature especially in the lower sections (when you sight the center section of the sail from behind) in both the main and the jib. They look flatter, which demonstrates that they can be trimmed flatter without compromising their shape. You can also create optimum full depth in the lower portion of the sail simply by easing the outhaul on the main or moving the lead forward on the jib.
Minimal vertical curvature allows the sail shape to vary enormously below seven knots and over 15 knots, wind outside the design of the sails’ "sweet spot" and where you need to make the most adjustments for control. Your main and jib sheet tension effect the twist of your sail controlling the openness of the top batten in each sail and its power in all conditions. The sail design can be optimized for 10 knots but remain competitive in extremely light and heavy conditions, as well.
This is a fundamental change in our thinking (just as the new rules have challenged us to rethink our race course strategies). For instance, you no longer confirm your outhaul trim by looking just above the boom at the tightness of the sail. Nor do you determine the top twist of your jib with your lead position.
Instead, look at area above your window on both your main and your jib and use your outhaul or jib lead to control the lower depth of the sail. To really see the vertical curvature and its impact on your sail shapes as you experiment, you need to get off your boat. You won’t believe how different your sails look.
Once you determine your best trim in given wind speeds, use graduated numbered bands at the jib tracks and outhaul to replicate your settings. Experimentation is the rule with these new designs. It provides an excellent new opportunity to speed test with people in your fleet and learn together how to optimize your trim.
See you on the water! We are happy to swap boats and let you look at your sails from off your boat. You will be amazed.
Anyone can point a boat higher into the wind, but you usually loose speed. So a more useful discourse has to involve something which I call "performance".
Performance is the result of the delicate relationship between apparent wind angle, apparent wind speed, sail power, boat speed and ballast. Performance is the greatest factor in determining the results of a sailboat race!
Lift and Drag
Every thing that affects your boat's performance can be expressed in terms of lift and drag. Whenever lift is produced, drag is the natural consequence. They go together hand-in-hand. Fortunately for sailors the ratio of lift to drag is not constant. It is possible to increase lift faster than drag, and vice versa. Understanding this relationship is useful in trouble-shooting performance problems.
Keels create lift because they slide through the water, both forward and to leeward. We call the leeward direction "leeway". It may not be perceptible, but all keels and centerboards have some leeway while sailing upwind. The orientation of your keel to this leeway determines the angle of attack of your keel.
When you point your boat away from the wind the angle of attack of the keel decreases. That means both lift and drag are reduced. Less drag enables the boat to speed up. The increased speed forces more water over the keel, which increases lift without significantly increasing drag. In this case, the ratio of lift-to-drag changes. More lift and less drag enhances performance. For many, it is counter intuitive to head down in order to gain progress to windward. This is a common mistake many sailors make in light air.
There is a limit to how fast your boat will go, however. Drag increases exponentially with boat speed. So there is a point depending on boat speed where lower angles will not significantly decrease drag. At top speed, you will have similar drag no matter what direction you point (unless you can plane). As you approach this point, upwind performance declines the lower you sail. Some people find themselves going very fast, but they can't hold their lane. By the time they get to the windward mark they are back in the cheap seats.
If you turn towards the wind, the angle of attack of the keel increases. Eventually the flow across the windward side of your keel starts to breakup, or stall. A stalled foil quickly looses lift and dramatically increases drag. Boat speed drops, which further provokes stall. Performance quickly degenerates at too high an angle.
Most sailors have an intuitive notion of a "groove" while sailing on the wind. Whether they understand the concept or not, a good helmsperson is better at keeping the keel's angle of attack between the two extremes described above. In light-to-moderate wind speeds, great sailors are able to keep their keels closer to the "verge of stall", usually without ever letting them stall. The verge of stall is usually the point where the maximum lift-to-drag ratio is found.
Rudder angle is the primary indicator for monitoring the lift of your keel. A mushy or leeward rudder angle is a symptom of a stalled keel, or a keel that is not generating enough lift. Many people get so distracted during the race that they forget to feel the rudder pressure. They then haveno way of knowing what the underwater surfaces are doing. They inevitably end up outside the "groove" for long periods of time.
If your boat has a wheel, it is important to have some indication of the rudder angle. Most boats sail with an optimum rudder angle of about three degrees.
Sails provide power by creating lift and drag. We can alter the sail's lift-to-drag ratio through sail controls.
In light air the goal is to maximize lift and minimize drag. Simply put, deeper sails tend to create lift faster then than drag, but if they get too deep the leeward aft edges start to stall. We monitor this stall with leech tell tails and visual clues such as distance off the spreader, and top batten angle. Increasing the angle of attack such as raising the traveler or sheeting the Genoa increases lift faster than drag, but if you go too far, the wind will strike the leading edge of the sail at too wide an angle and the leading edge will start to stall. When the leading edge stalls, the entire leeward side of the sail is vulnerable to stall. That is why most sailing handbooks suggest sailing with the windward tell-tail just lifting. In light-to-moderate air, the best sail trimmers are very good at keeping their sails at the verge of stall.
Lift generated by upwind sails is not directly oppostite of the lift generated by the keel. The degree to which the lift is not directly opposed is vectored into forward motion. As the wind increases, there comes a point where the opposition of these forces create heel. Too much heel is disastrous to performance for a multitude of reasons, but let it suffice that too much heel increases drag and reduces lift in both keels and sails. It's nature's way of equalizing the forces.
Centerboard boats can reduce heel by reducing their exposed underwater surfaces. Keelboats do not have such flexibility. Heel has to be controlled through minimizing the lift and drag that the sails produce. As it turns out, flat sails reduce lift and drag fairly effectively. Decreasing the angle of attack reduces both lift and drag. A flogging sail, however, creates almost no lift at all, but it generates an large amount of drag. Great sail trimmers are able to flatten their sails and maintain an appropriate angle of attack, but they rarely if ever let their sails flog. Their goal is to minimize drag and maintain the appropriate amount of lift suitable to the boat's ballast. It is better to have a little too much heel and keep it consistent than it is to over heel and then over flatten over and over again.
As it gets windier, the force of the sails continues to overcome the boat's ballast. Instead of lift pushing the boat abeam to leeward, the drag on the already flat sails becomes more influential. Drag wants to push the boat aft and to leeward. This increases the angle of attack of the keel. Somehow the excessive lift of the keel has to be relieved in order to control heel. Great helmspeople can feather their keels at extreme angles of attack so that a portion of the windward side of their keel becomes stalled. Too much stall and speed will diminish. Not enough lift will be produced and the bow will drop off to leeward. The sails will overpower the ballast. The boat will want to spin up into the wind. The result is usually a series of minor broaches as the boat cycles through successive stalls and overpowerments.
A Delicate Balance
Great sailors maintain a steady angle of heal in overpowering conditions because they monitor how much of the keel is stalled and the distribution of power across the sails. They concentrate on rudder angle and heel. If the keel wants to lift too much they experience too much rudder angle. The boat will want to climb into the wind. If they don't intervene by easing the main, the rudder will stall and the broach cycle starts anew. If they ease the mainsail too far, the boat is thrown out of balance and the jib pulls the bow to leeward. The cycle starts again. If the keel begins to loose too much lift they sense it early because the rudder suddenly feels mushy. They can ease the sails quickly and head off to reattach the flow around the keel.
In extremely heavy air, great sailors are constantly adjusting their sails as they attempt to delicately balance their sails over a partially stalled keel. The groove becomes almost impossibly narrow because the immense forces transform the rudder into an increasingly impotent tool. Teamwork is put to the test, as changes in course become impossible without sail adjustments.
Low and Slow
If you ever find yourself low and slow there is a high probability that something is stalled. The challenge is to find out which foil or foils is the culprit, and find a way to reattach the flow.
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