David Dsilo2


Dave Dellenbaugh Sailing

David Dellenbaugh is a champion helmsman, tactician, author, coach, rules expert and seminar leader who has spent his career helping sailors sail faster and smarter.Here are the learning resources that he has created to help you improve your racing skills.


Current can have a profound impact on strategy and tactics, and that's why we've included a "moving water" chapter in this book. Not surprisingly, current exists almost everywhere -- from tidal bays and sounds to rivers to wind-driven lakes -- so every sailor should know at least the basics.
      Before getting started, let's clarify one bit of terminology. In this book, when we refer to the current's direction, we are talking about the direction in which the current is going. For example, an easterly current (090 degrees) is flowing from west to east. This is the more commonly used way to describe current. Note, however, that it is opposite to the universal method for describing wind direction.

How to Judge Current  
Estimating current strength and direction is a little tricky because, unlike the wind, you can't simply see it on the surface of the water or feel it in your sails. However, there are a few guides you can use.

Charts and Tables:  The best way to predict what the current will be doing on the race course is to use published charts and tables. These give a fairly accurate guide to the velocity and direction of current that is caused by tides.

Anchored Things:  Once you get out on the course, the best way to measure current strength and direction is to look at buoys like the starting pin. Be careful not to confuse wave action with current. Anchored boats will also give you a good idea about current flow. If the committee boat is not pointed directly into the wind, for example, then it's probably being set by current. The actual lie of the boat depends on current, wind strength and the boat's windage.
      When racing in Annapolis, for example, you can watch the freighters anchored in the middle of the Bay to tell when the current turns out there. Deep ships lie almost entirely to the current, but take quite a while to swing when the current changes.

Water Surface:  Another important clue about current is the appearance of the water surface. When the current is flowing toward the wind, the water will be choppier than usual; when it's flowing away from the wind, the water is smoother. Look also for distinct lines of separation between different water surface textures. Current edges can be very sharply defined by color change, flotsam lines and temperature differences (e.g. the Gulf Stream), especially when the current is changing.

Current Stick:  Some sailors use a "current stick" to measure current accurately. This can be anything from an apple floating in the water to a more complicated device. The only requirement is that the majority of this thing is underwater so it is affected entirely by current, not wind.
      The idea with a current stick is that you set it in the water near a fixed object like a buoy. Then measure its distance and bearing from the buoy after a given amount of time. With some quick math, you can get a very accurate picture of current velocity and direction.

Instruments:  If you are fortunate enough to have the latest instruments on your boat, you will most likely get an automatic readout of current "set" (speed) and "drift" (direction).

Current Characteristics  
Remember that current will be affected, or created, by many factors. The first is wind. Sustained, strong breezes push water in the direction of the wind; when the wind subsides, the water flows in the opposite direction.
      Pressure systems also create current and influence tidal flows. Lows increase the height of high tides and prolong flood currents; highs push the water away, which increases the strength and duration of low tides and ebb currents. 
      When weather systems and wind act in concert, drastic effects can occur. On the East Coast, for example, an easterly storm drives water up into Long Island Sound and Chesapeake Bay; a strong cold front with a northwest wind drives water out. If you add in a full or new moon, which cause maximum tidal range, the current strength can be tremendous.

Basic Principles:  There are a number of predictable ways in which current will behave. Knowing these will help in planning your strategy.
      1) Current flow is strongest where the water is deepest, such as in a natural or dredged channel. This is partially because friction with the bottom slows the current. You can usually get out of current by heading for the shallower water close to shore.
      2. Current is strongest around prominent points and in narrow openings such as harbor mouths. There are usually back eddies on the down-current side of  islands, shoals and points.
      3. When a tidal-induced current begins to change direction, it changes first along the shore lines and later in mid- channel. On San Francisco Bay, for example, you'll often have a one or two-knot ebb beginning along the city front while the current is still flooding at two or three knots in the middle of the Bay.

Current Myths  
Before we go any further, let's talk about some common misconceptions that lead to strategic mistakes on the race course.
      I. The "lee-bow" effect:  there is no such thing as the lee-bow effect. In other words, if you are sailing upwind directly into the current, you can't gain by pinching to get the current on your lee bow. This myth has been explained many times, but many people still believe it.
      II. The "moving rug":  A second misconception has more serious strategic consequences. Many sailors believe that the direction of the current favor one tack over the other. This is not true. As long as the current stays the same for all boats, it doesn't matter whether you take the up-current or down-current tack first or last. All boats are on the same moving rug, and they are all being pushed in the same direction at the same speed -- so they will not gain simply by heading in different directions.

Current Wind   
One thing that adds to the challenge of current is the fact that it affects the wind you sail in. To understand this, imagine you are standing on the bank of a river. You feel no wind. You get into a sailboat and start floating down the river at two knots. Now you will feel a breeze of two knots, which is enough to start sailing.
      The same thing happens every time you are racing in current. Your actual sailing wind is a vector combination of the true wind (felt by an observer on land or on an anchored boat) and the wind caused by the current. This is one reason why race committees, measuring the wind from an anchored boat, will often set a biased line and course when there is current.
      As far as strategy goes, the fact that current affects your wind doesn't matter as long as the current remains constant across the course. If the strength or direction of the current varies in different areas, however, or if these change over time, then you will experience changes in the wind direction and velocity. So this must be a strategic consideration.

Sailing the Course in Current  
As we've seen, current can have a large impact on your strategy. When you are trying to round or pass objects that are anchored, it will also have a big effect on your tactics. Here are a couple of examples:

The start:  Starting a race in current offers a great chance to be smart and get a jump on the competition. Be sure you have a line sight to help you judge the position of the line. When the current and wind are going in opposite directions, you're likely to end up with multiple recalls. This is a great time to start at the leeward end (assuming you want to go left) because it will be easy to make the pin. However, don't start right at the committee boat, because it's too easy to get caught barging. And be careful not to be over early, since it will take a long time to get back against the current and re-start.
      When the current and wind are going in the same direction, most boats will be late for the start. This is a perfect time for two techniques: 1) Use your line sight to start in the middle and take advantage of the mid-line sag; or 2) Approach from a barging position when you want to start at the windward end. However, don't try to start right at the leeward end as this is very difficult.

Laylines:  The current affects your course over the bottom and therefore changes the laylines to any windward or leeward mark. When the current is pushing you away from the layline, it's easy to under-stand the mark and lose distance by trying to pinch up to the mark. Here the safest route is to overstand slightly -- this will keep you clear of the mess of other boats and eliminate the need to make extra tacks.
      When the current is pushing you toward a layline, the biggest potential mistake is overstanding. Prevent this by approaching to leeward of the "normal" layline or by avoiding the starboard layline completely until you are almost at the mark.

Rhumblines:  On reaches and runs, current will usually cause you to sail a longer course than necessary. With a bit of smart sailing, you can stick to the rhumbline and gain valuable distance. The best way to do this is by using a land sight. If you can see land behind the next mark, use this to set up a range so the mark stays in the same place on the land. This will take you straight toward the mark.
      If there is no land behind the mark ahead, take a compass bearing on the mark, and steer a course so this bearing remains constant. If you can't see the next mark, hold a steady compass bearing on the mark behind.

Racing success in current is a matter of attitude as much as anything else. Of course, you must know the geometry of how current affects boats and wind, but try to think of current as an opportunity. It's a great chance to get ahead by using your smarts.