Racing Upwind

The typical first leg of every racecourse for sailboats is an upwind segment. Ironically, a sailboat cannot travel directly upwind. 

Sailboats are limited in this ability and cannot sail any higher than a certain angle towards the wind.  At this point of sail,  the boat is said to be “close-hauled” or "beating to windward.”

Sails are shaped to produce lift, like airplane wings. But they are not rigid. When the wind hits them directly from the front, they flap and lose shape, causing a loss of forward motion. This is known as “luffing”. The boat essentially stalls and cannot move forward.

Traveling directly upwind can only be accomplished by “tacking.”

Tacking or “coming about” is a sailing maneuver by which a sailboat, sailing close-hauled,  turns its bow toward and through the wind. As the boat turns, the wind’s direction shifts from one side to the other relative to the boat.

To travel towards a windward destination, a craft must perform a series of tacking maneuvers in that direction. Each resultant course is a "tack.”  The tack having the wind over the right-hand side of the boat as the skipper looks forward is called a “starboard” tack.  The opposite tack is called a “port” tack.

The diagram below shows three courses: P1, P2, and P3.  These are a series of port and starboard tacks with the boat beating from A to B. The distance sailed on each of these courses is precisely the same. However, P3 requires only one tacking maneuver, while P1 requires 5. 

Since the distance sailed is identical, and each maneuver causes a slowing of the boat due to luffing, there always needs to be a reason to tack. If there is no reason to tack, don’t tack. Many racers tack too often.

Knowing when and how to tack a sailboat efficiently is crucial for winning races.

Improve Your Tacking Skills

Given an equal start and equal boat speed, why does one sailer “out-tack” another to be first at the windward mark? 

The answer lies in examining the physical elements that make up a tack.

The predominant elements are the entry speed, the deceleration of the boat as it begins to rotate toward the wind, the rotational speed as it comes about, the speed lost, the acceleration out of the tack, the exit heading,  and the overall tack angle.

Entry Speed:    Maximizing entry speed will increase the average speed through the early portion of the tack.

Deceleration:   As the boat turns into the wind, its speed decreases as the sails become loose and start flapping. Sailors refer to the distance made good towards the windward mark interns of speed. A boat with a faster speed in the windward direction travels further in the same amount of time. The speed in the windward direction is known as  “Velocity Made Good,” or VMG. To achieve a higher VMG, it is essential to maintain speed for as long as possible. 

Rotational speed:   As the boat rotates, it changes heading from the old to the new. The boat’s rotational speed should begin slowly, gradually increasing to reach a maximum before falling off as the new heading is reached. Avoid using a jerky “studder rudder” as it will act as a brake and slow down the boat.

Speed Lost:  This is the difference between the entry and minimum speeds during the tack. When the difference is expressed as a percentage, higher losses indicate a need for improvement.

Acceleration:  As the boat is coming about, the sails have no power. The boat reaches the minimum speed at the end of the tack. After it reaches a proper exit heading, its sails fill, and it accelerates. The objective is to swiftly maximize acceleration to reach an exit speed equal to the entry speed. 

Exit heading:  Coming out of the tack, the exit heading places the boat on a close-hauled course. If the boat is too close to the wind, it is said to be “pinching” and will have a reduced speed as it travels in a windward direction. If the boat is off the wind, it is said to be “footing” and will have a higher speed but make less progress windward.  Some coaches recommend footing on exiting and then rotating the boat toward the wind after it regains full speed.

Overall tack angle:   The overall tack angle is the difference between the before-tack and after-tack headings. The angle changes with wind conditions, boat design, sail design, rigging set-up, and tacking skills. Generally, it is about 90 deg. Assuming the same boat speed, a smaller angle results in greater windward progress.

This website offers tools to assess tacking techniques in terms of the physical elements described above. Having feedback enables the sailor to judge their effectiveness.

To improve your tacking skills, follow a cycle of practicing and feedback. This website is designed to provide feedback. 

Review the “Instructions for use”  tab, then try running the demo file in the “File Manager” tab.

Why Tackanalyst?

This website can evaluate racing sailors’ tacking skills as they learn techniques for making a good tack from instructors, coaches, or other sources. This site provides the tools to evaluate the sailing results and provide feedback to reinforce improvement.

Feedback is provided by recording sailing activities such as practices and races, importing the data into this website, and using the tools provided to evaluate performance.

The imported data is in standard GPX (GPS Exchange Format)  files.  They contain latitude, longitude, and time data on location points. The data is recorded by wearing a GPS device such as a Garmin fitness watch while sailing. 

Garmin watches can be set up to record GPS data at 1-second intervals.  Users then upload the data to the “Garmin Connect”  website (URL: https://sso.garmin.com/portal/sso/en-US/sign-in?clientId=GarminConnect&service=https://connect.garmin.com/modern/badges). The watch file is then downloaded as a GPX file. 

 After downloading the GPX file, it is uploaded to this website.  Headings, speeds,  distances, and other variables are calculated and displayed for further interpretation and analysis.