Metrics and charts reference

Speed and progress

SOG — Speed over ground(knots)

How fast the boat moves over the earth, measured from the GPS track. Current contributes to this reading, so SOG can differ from speed through the water.

Use it to compare pace, then look at VMG to see whether that speed is taking you in the direction you want.

VMG — Velocity made good(knots)

The part of your velocity directed along the wind axis: progress toward the wind when sailing upwind, or away from it when sailing downwind.

For example, sailing upwind at 8 knots and 45° to the wind gives about 5.7 knots of VMG. Sailing faster at a wider angle may not improve your upwind progress. An accurate wind reference is essential.

Distance and duration

These describe how far and how long you sailed. Check whether the view covers the whole activity, a saved segment or the sailing selected for analysis.

Course, wind and boat angles

COG — Course over ground(degrees)

The direction the boat is moving over the earth, derived from GPS positions. It describes the track rather than where the bow points.

Heading(degrees)

The direction the boat or aligned heading sensor points. Leeway and current can make heading differ from COG. A magnetic heading and a true heading also use different north references.

CWA — Course-to-wind angle(degrees)

The angle between the GPS course and the wind reference. It tells you how the boat’s path is angled to the wind. Read it with SOG and VMG when comparing pointing and speed.

TWA — True wind angle(degrees)

The angle between the boat’s heading and the true wind direction, when the required data is available. Because it uses heading, it can differ from CWA even at the same moment.

TWD — True wind direction(degrees)

The direction the wind comes from. Vantage may estimate the reference from the recorded sailing or use suitable measured wind data. An incorrect reference affects VMG, wind angles and sailing classification.

TWS — True wind speed(knots)

Wind speed from the available wind source. It is different from the wind-strength category you select for a session. Where recorded, TWS is available as an X axis in the Speed scatter view.

Heel(degrees)

The boat’s side-to-side inclination. Use it to examine the sailing angle and how it changes through a turn. The sensor must be mounted and calibrated to the boat.

Check the view’s sign convention before comparing port and starboard. Some views normalize angles to make the two tacks easier to compare.

Pitch(degrees)

The boat’s fore-and-aft inclination. Use it to examine bow movement and changes in trim. A loose device or a changed zero calibration can alter the reading without a corresponding change in the boat.

Stability measures

These measures describe variation during the straight-line sailing selected for analysis. Lower values mean less variation in the measured behavior. They are not percentage scores.

Compare similar boats, conditions and recording quality. The lowest value is not always the goal: sailing through waves can require deliberate steering and movement.

Steering Stability

How much the turning rate changes during the analyzed sailing. Lower values indicate more even steering; higher values indicate more changes in how quickly the course is turning.

Use it to investigate an unsettled run alongside the track and VMG. It is not a measure of how close you stayed to a particular compass course.

Heel Stability

How much the heel angle changes during the analyzed sailing. A lower value indicates a steadier heel angle.

Read it alongside the heel angle itself. A steady boat can still be held at an unhelpful angle, and unreliable mounting will also affect the result.

Speed Stability

How much acceleration changes during the analyzed sailing. It helps distinguish smooth speed behavior from repeated changes in acceleration and deceleration.

Compare it with SOG and VMG. It is not simply the gap between your fastest and slowest speeds.

Maneuver measurements

Vantage examines the approach, central turn and exit of each detected tack or gybe. Read these measurements together to understand how speed and progress change through the maneuver.

Entry SOG(knots)

Average speed over ground during the approach to the turn. Check it first when comparing exits: a boat that entered faster may also exit faster without having made a better turn.

Min SOG(knots)

The lowest speed over ground in the central turn. Compare it with entry speed to understand how much speed fell during the maneuver.

Exit SOG(knots)

Average speed over ground during the exit portion of the analyzed interval. Use the Time view to see whether speed is still building after the turn.

Avg VMG(knots)

Average VMG over the analyzed maneuver interval. It summarizes useful progress through the approach, turn and exit.

This is a mean measurement. It is separate from the chart control labelled Avg, which displays a median curve across maneuvers.

Min VMG(knots)

The lowest VMG in the central turn. It identifies the weakest moment of progress along the wind axis. Read it with Min SOG because both speed and sailing angle affect VMG.

VMG Distance(meters)

Net distance made along the wind axis over the analyzed maneuver interval: upwind for a tack and downwind for a gybe.

More distance means more progress over that interval. This is not a calculation of meters lost against a hypothetical perfect turn.

Max Turning Rate(degrees/second)

The greatest magnitude of course change per second in the central turn. A higher value indicates a faster rotation at the sharpest part of the maneuver.

Compare the resulting speed and recovery rather than assuming that a quicker rotation is always better.

Total Turn Angle(degrees)

The change between the average entry and exit courses. It describes how much the boat changes direction across the maneuver.

It does not directly measure the turn’s radius or add up every small steering correction. Compare equivalent tacks or gybes.

Max Heel(degrees)

The largest absolute heel angle in the central turn. It shows the greatest inclination reached, regardless of its sign. Use the heel curve or video to see when it happened.

Max Deceleration(knots/second)

The most negative acceleration before the minimum-speed point. It describes the strongest rate of speed loss in that part of the maneuver.

For example, −1 knot/second is a sharper slowdown than −0.3 knots/second. The value describes a rate, not the total speed lost.

Max Acceleration(knots/second)

The highest acceleration after the minimum-speed point. It describes the strongest rate of speed gain during recovery.

A brief acceleration peak does not necessarily mean a quick overall recovery. Check Exit SOG and the Time view too.

Additional sensor data

Heart rate(beats/minute)

Heart rate is available when a connected monitor or imported recording supplies usable samples. Compare the timing of effort with the sailing, allowing for gaps in the sensor recording.

Loads and other imported channels

Available channels depend on your recording or external-data import. Keep names and units consistent across sessions, and check time alignment before comparing them. The metric picker shows the channels available for the activity.

How to read the charts

Box plots

The line inside the box is the median: half the values lie above it and half below. The box runs from the 25th to the 75th percentile and contains the middle half of the values. A taller box means more variation.

The whiskers extend to the most extreme observed values within 1.5 times the box’s height beyond its edges. Values outside that range are outliers. An outlier is unusual within this set; it is not automatically an error.

Violin plots

The width shows where values are concentrated. A wide area means many observations lie near that value; a narrow area means fewer do.

Look at the measurement scale before comparing shapes. Two wide areas may indicate that the sailor used two different modes during the selected sailing.

Scatter plots

Each point relates the selected X and Y measurements. Use the pattern to investigate a question such as how VMG changes with heel.

A relationship does not establish the cause. Wind, waves, equipment and technique can change together, so return to the session context before drawing a conclusion.

Maneuver Time view

This view aligns turns around a shared maneuver reference. Negative times are before that point; positive times are after it. Follow the curve to see the approach, speed loss and recovery.

Individual curves show specific maneuvers. The Avg display uses the median of the selected curves. Where a band is shown, it contains the middle half of the curves at each time.

Maneuver Track view

This view compares the shapes of the turns in a common wind-relative frame. Use it to inspect how the boat changes direction, then check Time and the speed metrics to understand the cost of that path.

Performance scores

The overall performance score and the upwind, downwind, tack and gybe components use a 0–100 scale. They summarize where to look more closely; the underlying metrics explain how the sailing developed.

Where recent-history context is shown, it uses scored sessions for the same boat and wind category. The current activity is excluded from the baseline average. Scores are not a universal ranking across unrelated classes or conditions.

When a measurement is unavailable

An empty chart or missing value may mean that the recording has no usable sensor data, or that the selected interval contains no qualifying sailing. It does not mean that a zero was measured.

Try Full Activity, All and a basic GPS metric first. If a sensor channel is still missing, check the original recording or external-data import.