A large part of "smart" sailing involves your choice of "strategy" and "tactics." These terms are often used incorrectly and inconsistently, so let's define them now the way we will use them throughout this book.
Course Language
Before we actually get out on the course, let's define a few more terms so we will all be speaking the same language.
Ends of the starting line -- Each end of the starting line has many different names. The end that's usually marked by the committee boat is called the boat end, windward (weather) end or starboard end. The other end is typically known as the pin (buoy) end, leeward end or port end. The terms windward and leeward come from the sides of a boat that is crossing the line on starboard tack.
Sides of the course -- As you face the windward mark from the starting line, you will see the left and right sides of the beat. In between the left and right sides, of course, is the middle of the course. It's always good to know how far right or left you are of the middle. When sailing downwind, most people change sides, so "right" now refers to the right side as you are facing downwind. This is what we will use in this book.
The corners -- If you start at the leeward end of the line and sail on starboard tack all the way out to the layline, you are in the left corner. Someone who tacked around the committee boat and is now barely visible to you is in the right corner.
Rhumbline
The rhumbline is an imaginary straight line between two marks. Downwind, this represents the shortest distance you can sail and it's generally fastest to stay near the rhumbline whenever possible. On a windward leg, the rhumbline goes right up the middle of the course.
Laylines -- Laylines are a pair of imaginary lines that extend outward from each windward or leeward mark. They represent the course sailed by a boat that's just fetching the mark on port or starboard tack (or jibe).
At a windward mark, the laylines represent courses sailed by closehauled boats on opposite tacks. The angle between the two laylines is the tacking angle. Since different boats have different tacking angles, this means that laylines will vary for different boats. An Optimist pram, for example, will have very different laylines from a 12-Meter.
Another influence on the tacking angle and laylines are the wind and sea conditions. In flat water and moderate winds, the tacking angle for any boat will be very narrow. In light air and chop, however, that same boat will have a much wider tacking angle, so the laylines will be quite different.
When approaching a leeward mark, the laylines represent two boats sailing their optimal angles on opposite jibes. The angle between these two lines is the jibing angle. Like tacking angle, the jibing angle is a function of boat type and wave/wind conditions. Note that both upwind and downwind laylines are affected by current as well.
Position in the Fleet
One of the most important things you can know during any race is how you are doing against the competition.
The "ladder rung" concept -- To determine relative positions in a fleet, consider the windward leg as a ladder that the fleet climbs from rung to rung. The ladder rungs are perpendicular to the wind. All boats on a given rung are even. It doesn't matter where the boats are along the rung, as long as they are inside the laylines and the wind doesn't shift.
Measuring the straight line distance from a boat to the windward mark does not give the true sailing distance to the mark. Figure 8 shows two boats approaching the windward mark. Boat B is 1.5 boatlengths farther from the mark as the crow flies, but an inspection of their sailing tracks show that both will arrive at the same time. Proof of their evenness is that they will collide at the crossing point.
Tacking lines -- It can be difficult to use ladder rungs while racing because, obviously, the race course is not covered with parallel lines that are perpendicular to the wind. One thing you can do, however, is to use tacking lines or a hand-bearing compass.
Tacking lines are used to judge many things, including laylines (which we'll discuss in Upwind Tactics). They are also useful for identifying the ladder rung that you are on at any particular moment. In order to use tacking lines, you must know your "tacking angle" -- the number of degrees between port and starboard tack headings, in the existing conditions. Once you know that, the lines drawn on the deck of your boat will tell you not only your ladder rung but your upwind and downwind laylines as well.
Other boats -- One of the best ways to gauge your position in the fleet is to watch boats that cross just ahead or behind you. These boats will show how well you are doing relative to boats on your windward or leeward hips.
Height and speed -- It's important to know how you are doing relative to other boats on the course. Differences in boatspeed between any two boats may indicate not only that one boat is not sailing as fast as possible, but also that one boat is in more wind, a favorable wind shift or better current. Therefore, you should use other boats as tactical and strategic guides.
There are two things about other boats that are important to know: their forward speed and pointing, or height. Both of these should be measured relative to your own speed and height. If a boat on the other side of the course is pointing higher, for example, then either your boatspeed is not up to snuff, or he is in a lift or more breeze.
Understanding the Wind
If there's one generalization you can make about the wind, it's that it is always shifting. There are two basic patterns that cover almost all wind conditions. These are "oscillating" and "persistent."
Oscillating -- Shifts back and forth across an average wind direction. This is the most common type of windshift, since the wind is almost always oscillating. Likely causes are:
- Vertically unstable air: Oftentimes, the strong upper altitude wind blows in a slightly different direction than the weaker surface wind. Mixing brings high altitude shifts and gusts down to the surface.
- Thermal conditions: Cumulus clouds are caused by thermals, rising columns of hot air. They indicate unstable conditions.
- Offshore breezes: Wind that has passed over sun-warmed land is likely to have oscillating shifts.
When the wind shifts toward your bow, you call the shift a "header". When it shifts away from your bow, it is a "lift." Note that a header for a boat on port tack is a lift for a boat on starboard tack.
No matter which tack you're on, a counterclockwise wind shift is called a shift to the left or a "back". A clockwise wind shift is called a shift to the right or a "veer." The average wind direction is called the "median."
When the wind is at the median, the boat's heading on each tack is called the median heading. Throughout a race, changes in the boat's heading should be described in relation to the median. For example if the port tack median is 60 degrees, a heading of 55 degrees would be announced as "up 5." A heading of 65 would be "down 5." This makes the shifts easiest to understand.
Persistent -- The wind gradually or suddenly shifts one way and does not return to the original wind direction. Likely causes of a persistent shift are:
- Frontal passage or movement of a weather system.
- Ongoing development or decay of a sea breeze.
- Geographic shift, from a shoreline effect or a fan effect.
Combined oscillating/persistent -- Wind oscillates across a persistently shifting average. The most complicated and common type of shift. Any number of weather patterns can cause combination shifts.
Windshift Gains and Losses
As we have seen, any two boats sailing on the same ladder rung are even. When the wind shifts, however, the ladder rungs rotate so they stay perpendicular to the wind. This means the boats are no longer even.
The basic principle for gain and loss in a windshift is that the boat that's closer to the new wind direction gains (no matter which tack the boats are on). When the wind shifts to the left, for example, the boat on the left gains because she is all of a sudden on a higher ladder rung. Therefore, the strategic effect of a windshift depends upon a boat's position relative to the fleet.
The amount of distance that a boat gains or loses in a windshift is dependent on two things:
1) Lateral separation: The greater the distance between boats, the greater the gain or loss. In the example shown here, a boat that is 5 boatlengths away loses 3 boatlengths because of the windshift, while a boat that is 10 boatlengths away loses 6 boatlengths in the same shift. When boats are quite far apart, the potential gains from even small shifts are very large.
2) Degree of windshift: The larger the windshift, the greater the gain or loss. We have compiled a chart showing the rough amount you lose in various windshifts. The assumption here is that the boats have a tacking angle of 90 degrees.
Note that a windshift of only 5 degrees produces a gain or loss of 12% of the lateral separation. So if you are 8 boatlengths apart, you will lose one boatlength, or three boatlengths for a 15 degree shift.
Velocity Shifts
Most changes in wind direction are caused by actual shifts in the direction from which the wind is blowing. Sometimes, however, what appears to be a shift in wind direction is actually caused by a change in wind velocity.
To understand this, we have to start with an explanation of "apparent wind." This is the wind that you feel on a moving boat. Your apparent wind is a vector sum of the true wind plus the wind caused by movement of the boat over the bottom.
In a typical windshift, the true wind shifts direction (relative to fixed objects), and you can usually read this shift by the telltales on your jib. A similar thing happens when the true wind changes velocity -- your apparent wind changes in both direction and velocity. This is called a "velocity shift."
A velocity shift is a temporary shift in your apparent wind direction (and velocity) caused by a gust or lull, not by a shift in the actual direction of the wind. When you run into a lull, it will seem like you are being headed; when you get hit by a gust, it will seem like you're lifted. However, the strategic implications of a velocity shift are quite different from those of a real shift in direction, and the "smart" sailor must be very discriminating. One way to identify a velocity shift is that it is temporary -- it will wear off as soon as the boat has sped up or slowed down to its regular speed for that breeze. So before you tack on a header, wait a few moments. Have you really sailed into a lull? Will the wind soon shift back to where it was? Or is this a "real" shift?
We've just covered some of the basic principles and terms we will be using throughout the rest of the book. Now let's plunge ahead into the nitty-gritty of sailing smart!
Besides the shift terminology above, there are some other things you should know about the wind:
Apparent wind -- It's knowing about your apparent wind is very important tactically for understanding wind shadows, velocity shifts and the direction of your next puff.
Where your wind comes from -- It's important to watch the water to windward to see the wind that is coming your way. When you are in a moving boat, the wind you get is approaching from the direction of your apparent wind. So this is where you should be watching.
Puffs and lulls -- We usually measure wind speed in knots (nautical miles per hour). A temporary increase in wind velocity is called a puff or gust. A temporary decrease is called a lull. The puffiest wind is usually an oscillating breeze that's blowing offshore. Sometimes there is a correlation between velocity and direction; e.g. the puffs may generally come from the right.