Details

Zugriffe: 353

Luvmarke

• Segle über Layline
• löse Niederholer frühzeitig
• fiere Grossschot schnell
• Körper zurück bei Beschleunigung (Hebt Bug aus der Welle, dadurch dreht Boot schneller)
• Boot flach halten resp. eher Luvkrängung
• Körperschwerpunkt in der Mitte resp. wenn nötig leewärts (Deadroll)
• segle schnell nutze die Wellen (Kurve!)
• Trimm Segel auf Kurs,Windstärke (Cunnigham,Unterliek!)

Wellenreiten

gemäss Ed Adams

Shoulder down mode. In the flat water between wave sets,
sit up slightly and lean forwards with the forward shoulder down.

Punch the wave. Just as the bow meets the wave, throw the torso aft
and out and punch the wave by jabbing the tiller to leeward.

Unweight on the crest. As soon as the wave punch is made, come out
of the hard hike, sit up and forward to unweight the boat on the crest
of the wave, and pull the tiller up.

Power landing. As the boat drops into the trough, throw the weight aft
and out violently and put the tiller back down to leeward.

Details

Zugriffe: 362

The typical traffic pattern for a first beat sees a large concentration of boats early in the race (on the starting line) which spreads out as the fleet sails up the course, and each boat follows their respective strategy as best they can. Gains and losses are made on the beat due to differences in wind direction, wind velocity, and/or current strength. The degree of gain or loss caused by one of these variables is generally greater when there is more separation between boats. For example, a five-degree shift that occurs halfway up a beat will result in a relatively large gain for those on the left side of the course, since the fleet will be the most spread out at this point.

However, things change at the top of the beat, when the fleet is forced to converge at a single point, the windward mark. Many find course management in this portion of the race confusing and stressful, for there is an abundance of boats in a very small area, and decisions must be made quickly. However, strategy at the top of a beat actually becomes straightforward, due to the close proximity of all the boats. A few guidelines can make this part of the race very simple.

Why is strategy simpler at the top of the beat?
    A five-degree left shift at the end of a beat is not as significant as the five-degree left shift that occurred in the middle of the beat because the fleet is closer together. The advantage gained by any windshift, velocity change, or current variance, will be the smallest in this part of the race. Thus, these things deserve less attention. Environment changes should not be totally dismissed at the end of an upwind leg, but try putting the following two thoughts first in your mind when you arrive at this section of the race course,

1) Sail in Clear Air
As always, sailing in a clear lane should be a high priority. Sailboat racing is a game of inches, especially at the end of a beat. Anytime you are not sailing in clear air, you are losing valuable distance to those who are.

2) Get to the Starboard Layline First
The top portions of the windward leg can often be considered a race to the starboard layline. Your goal here is to be on starboard during your final crossing situation with the boats around you. For a port-tack boat approaching a starboard tacker who is on the layline, one foot short of crossing is the same as one boatlength behind, since they must fully duck the starboard tacker boat, then tack to windward and behind on the layline.

So if all else is equal, you should always try to lead boats to the starboard layline. For example, you are on starboard tack, near the windward mark, and you are not on the layline. You have a group of three port tackers approaching. The conservative move here is to tack to leeward and ahead of this group of boats and lead them to the starboard layline. You will then be the first boat in this group on starboard tack, on the layline. Provided your tack is made directly on the layline, any boat that has a crossing situation with you will be forced to duck and tack to leeward and behind.

Consider what happens if you do the opposite move now. You are again on starboard tack at the top of the windward leg, but not on the layline. The same group of three port tackers approaches you, and they all duck you. If any one of these boats gains one foot before you cross paths again, they will be ahead of you. Why? Because they will now be on starboard and you will be on port. They will have right of way during your last crossing, and since they gained just one foot, you will have to duck them, and tack to windward and behind.

This does not mean the one should blindly sail for the starboard layline. There may be some advantage near the port layline that presents an opportunity for a significant gain. But before going after that tasty puff on the port layline, make sure you can come back across without getting into much traffic. If the seats are already filling up on the starboard layline, that puff is probably not worth sailing for. Chances are, any gain made by sailing to favorable breeze on the port layline will be washed out when you have to duck several boats on the starboard layline while looking for a hole to tack into. Furthermore, if you are not one of the top seven boats in the fleet, it is often disastrous to sail to the port layline due to traffic and bad air from those who have already rounded the windward mark and are now sailing downwind on starboard tack.

Generally, when arriving at high traffic areas like the windward mark, it pays to simplify one's strategy by putting environmental factors (wind shifts, velocity changes, or current) in the back of one's head. Thinking purely in terms of boat to boat positioning will clarify the situation by minimizing your risks.

by
Stan Schreyer

Details

Zugriffe: 361

Wind Shear" and "Wind Gradient" may effect how you sail your Laser. Wind shear is a change in true wind direction with altitude, and wind gradient is a change in true wind speed with altitude. Thus, combined together, they affect the wind seen by your sail aloft, and may considerably affect how you trim your sail on each tack. Wind shear and wind gradient most often go hand in hand. In the USA and Canada, they occur in most sailing areas. Furthermore, their presence can be felt even at small altitude differences, such as at heights below the height of a Laser�s mast.

What causes wind shear and wind gradient

Within this height above the water level, there is a large amount of interaction between the wind, the water, and any nearby land. The wind at this level is influenced by the vertical stabilityof the air.

Vertical stability depends partially on temperatures. When cold air is above warm air, it is vertically unstable. In fact, because air expands as it rises, the case of colder air aloft and warmer air closer to the surface is the "normal" state of the air, in the absence of external effects. The warm air rises, and the cold air sinks, mixing the two layers together. This implies that when mixed, the two layers of air will tend to flow in the same direction and at the same speed. In such cases, there is not much wind gradient effects.

On the other hand, when warm air is above cold air (which is called a "temperature inversion"), the air is vertically stable: the colder and warmer air do not mix together as much. In vertically stable conditions, if there are also meterological changes creating any differences in the speed and direction of the winds at different heights above the water level, then these differences are not mixed. They are not reduced in magnitude due to mixture. The result is strong wind shear and wind gradient. That is, the higher the vertical stability of the air, the higher the likelihood of experiencing wind shear and gradient.

The degree of vertical stability (and hence the likelihood of shear and gradient effects) can be predicted based on the following factors:

• The temperature difference between the water and the air above it:

The colder the water, and the warmer the air right above it, the more likely it is to have vertically stable air. The cold water will cool the air right at the surface level, and a colder air level will stay under a warmer higher air level. This implies that you are more likely to experience wind shear and gradient in the springtime when the air is warming up but the water is still quite cold, or early mornings during the colder seasons when the water is still cold but the air warms rapidly.

• The weather system�s air characteristics:

Compared to the land, the sea has a relatively uniform temperature. It is not subject to the rapid heating and cooling by the sun the way the land is. In fact, the temperature of the water urcae remains constant both day and night. This is because of several factors. A part of the heat is used in evaporating water. The remaining heat is distributed over a deep layer of water. Although most of the sun's radiation is absorbed in a relatively shallow surface layer, the mixing coused by the wind and waves distributes this heat in a deep layer. The result is that there is little variation in the temperature of the sea surface.

Air masses that form over the seas are generally more stable vertically compared to air masses that form over the land. Wind shear and gradient are more likely to be encountered in these vertically stable marine air masses.

• The wind speed:

A stronger wind helps vertical mixing of the air. Thus, light winds allow tempreature inversions to form, and wind shear and gradient are more likely to be encountered when the wind is not blowing hard.

• Surface friction:

This is the primary cause of wind gradient. Friction reduces the wind speed at the water�s surface. On an average day, the wind 25 feet above the surface can be about 1.5-2 times the strength of the wind at the water level. You can expect more wind gradient in choppy or large wave conditions.

Symptoms of wind shear

The presence of wind shear can be detected by observing the differences in the way your Laser behaves on different tacks.

• Telltale behavior differences:

When there is wind shear (a difference in direction of wind aloft), the telltales on your sail will respond differently on each tack. With identical settings of your sail controls on each tack, you will notice that on one tack, the top of your sail will be "lifted", and on the other tack, it will be "headed". That is, on one tack, the top of your sail will be stalling, with the leeward telltales sagging; and on the other tack, the top of your sail will be luffing. If you use a masthead wind indicator, you will also see that it is pointing noticibly wider on the "lifted" than on the other tack. If you use a gooseneck-level wind indicator, when you trim your sail to your liking (probably based on the average wind angle at the hight of your steering and trimming telltales on your sail), you will see that the burgee is pointing at a considerably narrower angle of attack on the "lifted" tack than on the "headed" tack.

Of course, you will try to compensate for this by trimming your sail correctly for each tack, as described below.

• Boatspeed differences:

You will notice that your boatspeed (over the water) is higher on the lifted tack and slower, even terrible, on the headed tack! The Laser will "feel dead" on the headed tack. No matter how hard you try, you will not be able to get her going as fast as on the tack where the top of your sail was lifted. You need to mentally prepare yourself for this, and resist the temptation to tack back onto the lifted tack. (More on this below.)

• Helm differences:

With all the extra twist and extra boatspeed on the lifted tack, the helm will feel great. On the headed tack, with the sail sheeted in very tight and lousy boatspeed, the helm will fell "mushy" and it will be hard to find the groove upwind.

Symptoms of wind gradient

On a Laser (any boat without electronics), detecting the presence of high wind gradient will be tougher than detecting the presence of wind shear. Basically, you will notice that you are heeling much more than you would expect based on the wind you feel at the water level on your cheeks and neck. If you capsize (intentionally or inadvertantly), you will note that as you right the boat, the noise the wind makes on your sail will get much louder than you would expect based on the wind you feel on the daggerboard. Another subtle sign is provided by the gusts: the gust will arrive sooner than you would expect based on the progress of the ripples on the water, and the strength of the gust will be stronger than you would expect based on the darkness of the ripples formed by the gust on the water surface. Finally, you will fell that you sail faster than you are used to based on the wind you feel at deck level.

How to deal with wind shear and gradient?

Once, and if, you decide that wind shear and wind gradient are present, you an take some measures to take advantage of them. To compensate for wind shear:

• On the tack where the top of your sail is lifted, your sail will require more twist. Loosen the vang slightly, and tighten on the cunningham to open the leech.
• On the tack where the top is headed, you will require less twist: tighten up on the vang, and loosen a bit on the cunningham to close the leech.

Under high wind gradient conditions, on a big boat with masthead electronics, normally the skipper would reduce the "target boatspeeds" to take into account the fact that the average wind speed is actually lower than measured at masthead. This prevents the big boat footing off upwind at wide angles to achieve the unattainable targets boatspeeds based on wind speed at masthead. Similarly, the big boat skipper would need to prevent the temptation to head up downwind to achieve a target boatspeed based on wind aloft.

On a dinghy without any instrumentation like the Laser, the situation will be the reverse. You will feel you are sailing really fast for the wind, and you will have a natural inclination to point while sailing upwind, and to foot off while sailing downwind. This is what you need to avoid: resist the temptation to continuously pinch to gain VMG upwind, and the temptation to continuously head off to gain VMG downwind. Watch the boats around you to see if you are fast, or if everybody else is fast, too. As always, base such course alteration decisions on the usual tactical factors and the changes in wind speed and direction observed. It is more likely that you "feel fast" because the wind is stronger that you feel at deck level rather than because you seem to be "hot" today.

Wind shear, wind gradient, and forecasting wind shifts

When the air is vertically stable, the cooler air at the surface level and the warmer air at higher levels behave more independently. The warmer air aloft responds to changes in atmospheric conditions faster than the cooler air below. It takes some time for the changes in the wind speed and direction observed at high levels to translate to the lower level. You can make use of this to predict wind shifts, and to set your racing strategy accordingly.

The best example of wind shear and wind gradient is a filling sea breeze on a warm spring day: The water is cold, and cools the air at the surface level, while the sunshine warms the air aloft, creating the vertically stable conditions. (We will base the discussion on the Northern hemisphere.) In the Northern hemisphere, a sea breeze moves clockwise to the right as it builds (i.e., it veers). The effect is more pronounced the futher Northh you are sailing. The fefect ceases at the equator and then reverses in the Southern hemisphere.

When a sea breeze starts filling in, the first effects will be seen at the very top of the sail where the air is warmer. If you are sailing on starboard tack, you will notice that the very top leeward telltales tha were drawing fine before will stat stalling. If you are sailing on port tack, you will note the top 1/4 of the sail starting to feel mushy and almost luffing. This is all happening because with the onset of the sea breeze, the wind at the top of the mast may be 15-20° to the right of the wind on the water.

Over time, the sea breeze will fil in downward as well as towards the land. So, you will soon start seeing the veering to the right at lower and lower portions of your Laser sail. How do you use this information for strategic purposes? The strategy is clear. For the period of time until the sea breeze settles in, it will continue veering. Thus, you need to treat it as a persistent shift for this duration, and sail to the right side of the course upwind.

The problem is that to sail to the right side, you need to get on port tack, but the port tack is the tack that is "headed" due to the wind shear aloft. The more you sail on port, the more severe the "header" aloft will become, and the more your boatspeed will suffer. Avoid the tendency to back onto starboard where everything feels good. Stick out on port tack and work hard to achieve whatever performance you can. Protecting the right will pay off in the long run.

This is all based on a wind shear to the right. You may also encounter wind shears to the left. In the Northern hemisphere, this may be associated with a dying breeze, or when sailing towards a shore. If you notice a shear to the left, this time you want to aggressively protect the left side of the course.

Finally, note that the only thing needed for large wind shears is a vertically stable air mass, cool air down, warm air on top. That is, don�t forget the wind shear possibilities in the scorching summer days, or at early mornings when the rising sun warms the air much faster than the sea.

Details

Zugriffe: 323

Situation: Here we are charging upwind, full-speed, bow even above, bow even below fifty boats on either side. We have a marginal lane. With a little lift, we can hold here and maybe boatspeed our way out of harm‘ s way. With a little header, we are likely to fall into the boat to leeward and be forced into decision-making-mode. We were not entirely sure as to which side of the course was going to be better. The seabreeze was oscillating, but only slightly and in regular and short intervals. Small cumulus clouds are making little impact on the racecourse and the current seems pretty marginal across the racing area. What do we do? The answer may be simpler than you think.We find ourselves in situations like this often enough. Once we have gone through our starting routines and come off the line with full speed and with breathing room, it becomes difficult to execute the perfect plan of attack. lt usually goes without saying, on skewed racecourses, there are important strategies to follow. If the current or geography demands we go right in order to win, then we will do our best to start in the boat-third ofthe line, and get going right as soon as possible after the gun. Likewise, ifthe left has been working all day, then starting at or near the pin in clear air will give us a higher percentage ofpossibility to win. The rest, after the start shakes itseif out with proper traffic-handling skills and integration between shifts and strategy. A good start improves our percentage, whereas a bad start sends us praying to the comeback deities that they may be merciful.During last week‘ s Princess Sofia Regatta in Palma, before a race was about to start in similar conditions to those described above, a buddy of mine sailed past and asked the seemingly innocent question: “Which way you going this beat?“ 1 had done a split to check the breeze and finished a race on the same racecourse not twenty minutes before, and yet 1 had no strong inclinations. Realizing that the Laser dass can sometimes be a grunt-fest where the fleet races with ridiculous amounts of effort towards the port-tack layline whereupon any decent tactical awareness sets in, 1 replied ‘If 1 have a good lane, I‘ll go left. If 1 have a bad start, I‘ll go right.“ As 1 said it 1 thought to myseif, Boy, there ‘s an understatement in Laser sailing. When in reality it is a fairly decent strategy.Sailboat racing, particularly Laser racing often breaks down to this very simple idea: lane management. Without proper administration of your angles, holes, and positioning in the first few minutes ofthe first leg away from the starting line, you will undoubtedly lower your likelihood of success. Especially in one-design racing, anytime where boats are essentially going the same speed offthe line, a pattern emerges. We‘ll call it the “First Beat Blues.“ Time after time, the pattern reemerges and a certain level of predictability arises within the fleet dynamic.Regardless of fleet size, the pattern on courses square to the breeze is usually the same. Boats that get off the starting line with good lanes generally stay on starboard as long as those lanes are still available. A certain percentage of boats that get poked out in front may be inclined to tack and cross. This is definitely recommended if you have the chance, but is usually an option limited to about 5% of the fleet who had the best starts. The part of the fleet that made it off with usable lanes from the middle and pin thirds of the line largely continue on starboard tack. This percentage of the herd is usually near 50% of the group. The use of herd will now be replace fleet as the predictability of the pattem of their action increases in stable racing conditions. Any stragglers from the front row of that herd traveling towards the left side of the grazing area are forced to make a decision: sit in bad air, or tack. More than often the intelligent move is to tack and clear as soon as possible in the search for clear air, greener pastures ifyou will. These unfortunate souls make up about 10% of the pack. Often times, boats starting in the boat-third of the starting line get going right as soon as they see that it is not reasonable to gradually sail into the hips of the boats to leeward of them. A substantial group. conscious of their intent to go right will tack off as soon as a lane opens towards the right, making up for another 25% of the larger herd of racers. The final 10% of the herd is made up of boats that simply cannot make up their minds where the best options could be. These boats are coming from positions in the second row, late at the boat-end, or failed approaches too late in the melée of the start. This breakdown of the pattern of the fleet is what you would see in a large percentage of most one-design racing on square racecourses. Freak wind shifts and skewed starting lines alter the numbers, but the patterns primarily remain alike.What do we do with this? Whether we know it or not, our dependence on this pattern greatly impacts our understanding of tactics and strategy. When we get off the line in clear air, it is highly unlikely that we would quickly tack and duck a large number of boats, even though the other side of the racecourse has just as high a likelihood of better conditions. When we get off the line in clear air, we go straight until that clear air is compromised, a beneficial shift falls into our laps or we trip over the port-tack layline.

Monday Morning Tactician Says: The observations of first-beat patterns in boat races do not necessarily teach us new information as much as they bring forth understanding of the big picture. Without a full understanding of fleet/herd dynamics throughout different legs and mark-rounding situations, it is difficult to anticipate and improve our position on the results board. However, learning to see the fleet as a group of generaily docile creatures that crave clear air, and dislike unnecessary maneuvers, we can then take advantage of that dynamic by sometimes breaking from the normal dynamic and other times going with the flow. Knowing when to use the two different theories is the hard part of sailing. Reading the fleet does not have to be.

by Andrew Campell