Learn to track, analyze, and improve your sailing with ChartedSails. This free course covers GPS data capture, race analysis, and performance optimization.



Welcome to ChartedSails' Sailing Data Analysis Course! We're delighted to have you join our community of data-driven sailors. This course will help you learn how to track, analyze, and improve your sailing performance through powerful data visualization and insights.

## What You'll Learn

Throughout this course, we'll cover:
- [How to capture your sailing data](/sailing-data-course/capturing-data) with the ChartedSails app, GPS devices, and smartwatches
- [Sailing with your group](/sailing-data-course/groups) to share data and compare performance
- [Preparing your data](/sailing-data-course/preparing-data) in the most effective way
- [Tools to use in your data analysis](/sailing-data-course/tools-of-the-trade) and the measurements that drive speed
- Analyzing races with [proper setup](/sailing-data-course/race-setup) and [data visualization](/sailing-data-course/race-analysis)
- [Sharing insights](/sailing-data-course/sharing-insights) with your crew and team
- [Using video](/sailing-data-course/improving-with-video) to improve technique
- [Live coaching](/sailing-data-course/live-coaching) for real-time feedback on the water
- [Using ChartedSails with AI](/sailing-data-course/ai) to explore your data in new ways


## Who This Course Is For

This course is designed for:

- Competitive sailors looking to gain an edge in races
- Coaches who want to provide data-driven feedback to their teams
- Recreational sailors interested in improving their skills
- Anyone curious about the intersection of sailing and data analysis

No prior experience with data analysis is required, though basic sailing knowledge is assumed.

## Getting Started

If you haven't already created an account, you can sign up at [chartedsails.com](https://www.chartedsails.com). All the techniques in this course will be demonstrated using the ChartedSails platform.

ChartedSails is free to use. Upload your data, replay your sessions, and view your speed and course over ground. When you're ready for deeper analysis — VMG breakdowns, race segmentation, maneuver stats, and more — you can upgrade to a paid plan at any time.

The best way to get started is to [download the ChartedSails app](/app) on your phone and record your next sail.

## How to Use This Course

Each section builds on the previous one, so we recommend working through them in order. However, if you're already familiar with certain aspects, feel free to jump to the sections most relevant to you.

Throughout the course, you'll find:
- **Step-by-step guides** for using ChartedSails features
- **Pro tips** from experienced sailors and coaches
- **Visual examples** to illustrate key concepts
- **Action steps** to help you implement what you've learned

---

Ready to start your journey toward faster, more data-driven sailing? Let's begin with [capturing your sailing activities](/sailing-data-course/capturing-data).


Welcome to the Sailing Data Analysis Course

Learn how to capture sailing performance data with the ChartedSails app, GPS devices, and smartwatches. Start tracking your sailing sessions today.

What is the difference between COG and Heading?

What is the best way to record a group of boats?



> "You can't improve what you cannot measure"

If you want to sail faster, you need to start by capturing your performance data. It's a simple habit to build, and the most common regret we hear from sailors is: "I wish I had recorded my first year with the boat." So start today—and don't skip a session!

## The ChartedSails Mobile App

The easiest way to start recording your sailing is with the ChartedSails app on your phone. No extra hardware needed — just tap Record and go sail.

The app captures your GPS track, speed, and course. It also lets you:
- **Ping the marks** during a race, so ChartedSails knows exactly where the marks are for race analysis
- **Use the race timer** to capture the precise start time
- **Add comments** while sailing to note conditions, tactics, or anything you want to remember
- **Upload video** directly from your phone after sailing

[**Get the ChartedSails app →**](/app)

## Dedicated Sailing GPS Devices

For the most complete data, many sailors use a dedicated sailing GPS. These devices are purpose-built for the marine environment and capture additional data like heading, heel angle, and pitch.

### Velocitek Prostart

<img src="/assets/img/velocitek-prostart.webp" alt="Velocitek Prostart" class="img-fluid" style="max-width: min(100%, 400px);"/>

- **Pros**: Excellent for starts, large screen, easy to use, and great for all types of sailing.
- **How to use with ChartedSails**: Your data is automatically recorded every time you sail. Just plug the Velocitek into your computer and you will find a VTK file that you can upload to ChartedSails.
- **Recorded data**: GPS position, speed, course, heeling and pitch angle, heading.
- Pings of the marks and start timer are also recorded.

### Vakaros Atlas 2 / Atlas Edge / Atlas

<img src="/assets/img/vakaros-atlas.webp" alt="Vakaros Atlas 2" class="img-fluid" style="max-width: min(100%, 400px);"/>

- **Pros**: High precision, easy sync, and great for all types of sailing.
- **How to use with ChartedSails**: Your data is automatically recorded every time you sail. Just use the Vakaros mobile app to export your data. You will get a VKX file that you can upload to ChartedSails.
- **Recorded data**: GPS positions, speed, course, heeling angle, pitch angle, heading.
- Pings of the marks and start timer are also recorded. If you are participating in a RaceSense event, you will receive wirelessly the position of the starting line and the race timer. These will be recorded too.
- With a Calypso wind sensor, both apparent and true wind speed and direction are recorded.
- With a boat speed sensor, boat speed, water temperature and water depth are recorded.
- With a Cyclops load sensor, you can record the load on your rig.

- **Important**: If your Atlas is not mounted in a fixed position, make sure to turn off the "Fixed Mount" option in the settings. Otherwise, the heading angle, heeling angle and pitch angle will be incorrect.

### Sailmon Max

ChartedSails is compatible with the Sailmon devices. As of March 2025, Sailmon announced that they were acquired by Vakaros. It's not clear yet how long the Sailmon devices will be offered for sale but ChartedSails will continue to support them.

- **Recorded data**: GPS position, speed, course, heeling and pitch angle, heading.
- Unfortunately, Sailmon Max does not save the pings of the marks in the data file.

## Smartwatches

Many sailors use smartwatches like Garmin for convenience. The best part: with automatic synchronization, you connect your Garmin account to ChartedSails once and every sailing activity syncs automatically. You don't have to remember anything — just sail and your data appears in ChartedSails.

[**Read our Garmin Guide →**](/blog/take-your-garmin-watch-sailing)

## Common Questions

### What data should I record?

Most devices will automatically capture your GPS positions over time (your track), your Speed over ground (SOG), and your Course over ground (COG).

Dedicated sailing GPS devices will also capture additional data such as heeling angle, pitch angle and heading. And when connected to additional sensors, they may be able to also capture wind speed and direction, boat speed, water depth and temperature, and more!

In general, if your GPS device can capture it, you will be able to see it in ChartedSails. If something is missing, let us know!

### What about recording races?

Sailing GPS devices will also capture your pings of the marks and the time of the start timer. This makes it much easier to find the race in your track. ChartedSails will also load and display this information.

The ChartedSails mobile app also supports mark pinging and the race timer, giving you the same benefits without a dedicated GPS device.

### Recording frequency?

The recording frequency controls how many points per seconds are saved by your GPS. In general, the higher the frequency, the more accurate the data, but the more battery it will consume.

For traditional sailing, a frequency of 1Hz is usually sufficient but we would still recommend 5Hz to have smoother tracks and a better experience.

For foiling and other fast boats, 5Hz is a minimum.

### What is the difference between COG and Heading?

COG (Course Over Ground) is the direction in which the boat is moving over the ground, while Heading is the direction in which the boat is pointing. The difference between the two can be significant, especially when sailing upwind or downwind.

To capture heading, you need a device that has a compass. Most dedicated sailing GPS devices will have this feature, but not all smartwatches or phone apps will.

### Which file format should I use?

ChartedSails supports the most common file formats: GPX, CSV, TCX, FIT, and NMEA. We have inspected many files by hand so that we can load them properly, use the right units and make the best use of the data available.

If the files exported by your GPS are not recognized by ChartedSails, please contact us. We will do our best to support your device.

**Velocitek and Vakaros both offer a special format (respectively VTK and VKX). These formats are the most complete and the only way to get the best experience in ChartedSails.**

### What is the best way to record a group of boats?

The best approach is to have everyone in your group use either the ChartedSails app or their own GPS device. When everyone is part of the same [group](/sailing-data-course/groups), the data comes together automatically. Read our [Groups guide](/sailing-data-course/groups) for more information.

For large events and coaching clinics, see our [Live Coaching guide](/sailing-data-course/live-coaching).


## Your Next Steps

1. **[Download the ChartedSails app](/app)** and create your boat
2. **Set up your device** on your boat and make sure you are familiar with operations (recommend testing everything on a walk or bike ride!)
3. **Test it out** on your next sail

Once you've selected and set up your recording method, you're ready to [create or join a group](/sailing-data-course/groups) so you can share data and compare with other sailors.


Capturing Your Sailing Activities

Learn how to create a group in ChartedSails, invite your fleet, and share sailing data automatically with your training partners and competitors.

Your own sailing data is valuable. Your data alongside the boats you race and train with is transformative. When you can see your track next to the boat that beat you to the windward mark, you start to understand *why* — and that's where real improvement begins.

Groups in ChartedSails make this easy. Once you're in a group, your data comes together automatically so you can replay races with all the boats, compare performance, and learn from each other.

## Creating a Group

You can create a group from the web or the mobile app.

**On the web:** Go to your [Groups page](/profile/groups) and click "Create Group." Give it a name — your fleet, your sailing club, your training crew — and you're in.

**On mobile:** Open the Groups tab and tap "Create Group."

## Inviting Other Sailors

Once your group exists, you'll have a six-letter invite code. Share this code with the sailors you want in the group — via text, email, WhatsApp, or on the whiteboard at your club.

To join, they go to the Groups page (on web or mobile), tap "Join Group," and enter the code. That's it.



## How Sessions Work in a Group

Once everyone is in the same group, getting your data together is mostly automatic.

**The best approach: schedule a session in advance.** Before your sailing day, create a session in the group (e.g., "Saturday Training"). When group members upload their data from that day, it will automatically be added to the session. No extra steps needed.

**If you didn't schedule ahead,** any group member can assign their session to the group after uploading. On mobile, open the session and tap the group button to assign it. On the web, click the share button and assign it to the group. Once one person has done this, other group members' uploads for the same time period will join automatically.

**Missing someone's data?** ChartedSails will show you if a group member has uploaded data for the same time period but hasn't added it to the session yet. You can pull their data in with one click.

## What You Get

With everyone's data in the same session, you can:

- **Replay the race** with all boats visible — watch the whole fleet from above
- **Compare tracks** to see different lines and strategies
- **Analyze performance** side by side: who had better VMG upwind, who sailed a shorter distance, who lost time on maneuvers
- **Generate session reports** with leg-by-leg breakdowns for all boats

The more boats in your group, the more you'll learn from every session.

## Pro Tip

Encourage everyone in your group to record every session, even casual practice days. The habit of consistent recording pays off when you have weeks and months of data to compare trends and measure improvement.

Now that you have your group set up, let's move on to [preparing your sailing data](/sailing-data-course/preparing-data) for analysis.

Sailing With Your Group

Learn how to prepare your sailing data in ChartedSails. Trim GPS tracks, set wind direction, organize sessions, and add notes for effective analysis.



Before you can analyze your data, we need to do a little bit of preparation and organization. ChartedSails makes this easy and intuitive.

## Getting Your Data Into ChartedSails

How your data gets into ChartedSails depends on how you recorded it.

**ChartedSails mobile app:** If you recorded with the app, your data uploads automatically at the end of your session. There's nothing extra to do — just open ChartedSails on the web or on your phone and your session is ready.

**Garmin watches:** If you've connected your Garmin account, your sailing activities sync automatically. You don't need to touch anything — just sail, and your data appears in ChartedSails.

**Dedicated GPS devices (Velocitek, Vakaros, etc.):** Export the file from your device and upload it to ChartedSails. Click the "UPLOAD" button on your dashboard and drag and drop your file into the upload area. ChartedSails will automatically detect the file type and start processing it.

![Uploading a file to ChartedSails](/assets/sailing-data-course/upload.png)

After processing, ChartedSails will ask you to provide some information such as the name of the boat. If it's the first time you upload data for this boat, the program will also ask you to provide the boat type and the sail number. The boat type is important to properly represent the length of the boat and will also be used for some racing analysis.

![Add boat](/assets/sailing-data-course/add-boat.png)

If your boat class does not already exist, you can quickly add it.

## Add More Boats

If you were not sailing alone, the easiest way to get everyone's data together is through [groups](/sailing-data-course/groups). When you're all in the same group, data from the same sailing day comes together automatically.

If you already have the files for other boats (for example, a coach collected everyone's data), you can add them directly with the "ADD BOAT" button and repeat the upload process.

## Tracking the Marks

Accurate mark positions make a big difference in race analysis. There are a few ways to get mark positions into ChartedSails:

**From the ChartedSails mobile app:** Ping the marks as you pass them during the race. The app records the position, which ChartedSails uses automatically when you set up the race.

**From your GPS device:** Velocitek and Vakaros devices also record mark pings. These are loaded automatically when you upload your data.

**From a separate GPS file:** If someone recorded the mark positions with a separate device, you can upload the file (VKX, GPX, etc.) and assign it to a boat named "mark 1" (or any name you choose). ChartedSails will recognize it as a mark — it won't appear in the list of boats and will be used for race analysis.

## Provide Wind Direction

Sailing insights depend heavily on the wind direction. ChartedSails automatically fetches weather data for your session location, giving you a baseline wind direction and conditions for the day.

If you have wind instrument data from your GPS device, ChartedSails will display this as instrument data and on the graphs, giving you even more precise wind information.

You can also set the wind direction manually using the rotating compass in the top right of the screen — rotate the map until the wind is coming from the top.

![Set the wind](/assets/sailing-data-course/help-setwind.gif)

## Trim Your Session

It regularly happens that we keep the GPS recording on the freeway back home and this makes for some disturbing maximum speed.

You can easily trim-off data before and after sailing with the "EDIT" button.

![Trim session](/assets/sailing-data-course/trim-session.webp)

We recommend keeping the entire day of sailing. From leaving the dock until you return to the dock. We will discuss later how to highlight specific races in the day.


## Tips to Make the Most of Your Data

Your GPS will capture most of the technical information, but we've learned that a few simple notes during your sailing day will make a huge difference in transforming that data into real improvements.

### 5 Key Things to Record During Your Sail

Even the best GPS can't capture everything. Here are the critical details to note during your sailing session:

1. **Crew Information**
   Who was on board? Different crew weights and skills affect performance.

2. **Sail Configuration**
   Which sails did you use? Note any changes made during the session.

3. **Weather Conditions**
   Note wave conditions and any significant changes throughout the day. ChartedSails fetches wind data automatically, but your own observations about gusts, shifts, and sea state add valuable context.

4. **Start Times**
   Modern sailing GPS devices and the ChartedSails app capture this automatically with the race timer. If yours doesn't, write down the exact time of all starts.

5. **Experiment Details**
   Working on improving jibes? Trying different heel angles? Note the time and nature of any technique experiments you try.

### How to Capture These Notes

The easiest way is to use the **Comment feature** in the ChartedSails mobile app. You can add comments while sailing — tap the comment button and speak or type a quick note. Your coach can also add comments from their device during the session.

Other simple options:
- Use a small waterproof notebook
- Take quick voice memos on your phone
- Snap photos of the crew, whiteboard and sails with your phone


Here's what effective notes might look like:
```
April 12 - Team: Alex, Maria, Thomas
- 12:30-1:00: Light wind 8-10kts, flat water, tested new jib trimming technique
- 1:15: Wind shifted +15°, increased to 12-14kts
- 1:30-2:45: Five practice starts, working on acceleration
- 2:50-3:30: Three races, using higher pointing angle upwind
```

### Adding Your Notes to ChartedSails

When you first open your session in ChartedSails, add your notes:
- In the session title (e.g., "J/70 Training - 15-18kts - New jib")

- Using the notes feature on the timeline
![Add notes to the timeline](/assets/sailing-data-course/add-note.gif)

- Create highlights on the timeline to quickly find interesting moments

![Create a named selection](/assets/sailing-data-course/create-named-selection.webp)


## Action Step

Before your next sailing session, create a simple template for your notes. Having a structure makes it easier to jot down the important details quickly.

Now that you've learned how to prepare your data, you're ready to move on to [understanding the tools of the trade](/sailing-data-course/tools-of-the-trade) that will help you sail faster.


Preparing Your Sailing Data

Master ChartedSails' measurement tools and instrument panel. Learn to analyze sailing data, track performance metrics, and make accurate measurements for race improvement.

2. Straight Line Speed: Understanding VMG



Now that we have uploaded our data to ChartedSails, added all the files and
notes in our possession, it's time to learn what are the different types of
measurements we can take, and how to do it effectively.

We will start by discussing the tools available in the interface to take
measurements and then discuss interesting measurements.

## The Instrument Panel

In the left part of the screen, you will find the Instruments panel. This panel displays all the data available for all the boats at a given point in time indicated at the top.


![The instrument panel](/assets/sailing-data-course/instruments.png)

You can resize this panel to make it wider and show more information:

![Resize the instrument panel to show more information](/assets/sailing-data-course/resize-instrument.webp)


## The Performance Panel

The Performance Panel is the second tab in the same window. Where the instruments always show data at one point in time, the performance panel shows **aggregated data**.

Aggregation is a data analysis term that simply means that we are grouping many points together and summarizing them into one or a few values. The simplest example of aggregation, and perhaps most often used in sailing is the **Average**. Another one that you are familiar with is the **Maximum**.

A key aspect of aggregation is understanding what data points have been summarized. ChartedSails always makes this clear by showing at the top of the panel the points that have been included.

By default, ChartedSails aggregates over the entire day so you can see what distance you sailed, what was the average speed, max speed, etc.

![Performance panel](/assets/sailing-data-course/performance.png)

You can very easily zoom on a specific time period by clicking on the timeline and dragging the mouse. When you do this, the Performance panel updates to show you data for just the interval you selected. Notice also that the time at the top changes to show the selected interval.

![Make a selection](/assets/sailing-data-course/selection.gif)
![Observe the performance panel](/assets/sailing-data-course/selection-performance.gif)

ChartedSails can do even more complex aggregation for you. In the next chapters, we will discuss how to compare the performance of different boats in one race or one leg of a race, even when they started and finished at different times.

## The graph

At the bottom of the screen ChartedSails represents the data visually. By default the Speed Over Ground is represented.

To see other variables, you must first select a specific boat and then select which variable to look at:

![Use the graph](/assets/sailing-data-course/graph-variables.gif)

## Boat tails

Another essential tool is the tail selector. It controls how much of the track is represented on the map and lets you visually represent the speed by coloring the track.

In Tail mode, ChartedSails will only show the last 10 minutes in a fading color that is unique to each boat.

In Full Tail mode, ChartedSails represents the entire track of the boat.

In Speed mode, ChartedSails represents the Speed Over Ground. The scale is specific to the current selection.

![Tail selector](/assets/sailing-data-course/tail-selector.gif)

## Quick Measurement

The last tool we will discuss is the quick measurement tool. This allows you to very easily take measurement over any straight line segment. It makes it trivial to compare angles and speeds of tacks or multiple boats.

![Quick measurement](/assets/sailing-data-course/quick-measurement.gif)




## Three Areas to Focus On

### 1. Practice Volume: Quantity Matters

To get results, you need time on the water. ChartedSails automatically tracks:

- Total sailing time
- Number of tacks executed
- Number of jibes completed
- Distance sailed

**Action Step:** Build a profile of what a regular training day looks like for you, then set a goal to increase your numbers by 10-15% next time.

### 2. Straight Line Speed: Understanding VMG

Velocity Made Good (VMG) is the speed component directly toward your destination, whether sailing upwind or downwind. It's your most important performance metric.

ChartedSails makes it easy to analyze your VMG performance:

1. Hover your mouse over the chart to see SOG (Speed Over Ground), VMG, and TWA (True Wind Angle) for each tack
2. Look for patterns in your data to answer these questions:

   - When is your VMG the highest?
   - What boat speed and angle produce your best VMG?
   - Do you tend to pinch (sail too high) or foot (sail too low)?
   - What heel angle gives you the best performance?

**Action Step:** Identify your optimal TWA for maximum VMG in different wind conditions and make note of it for future reference.

### 3. Maneuver Efficiency: Tacks and Gybes

Every tack or jibe costs you energy and speed. The key questions are:
- How much speed did you lose during the maneuver?
- How long did it take to regain your speed?

ChartedSails has a dedicated **Maneuver Analysis** tab in the instruments panel. It automatically detects all your tacks and gybes and shows you the VMG during each maneuver. At the bottom, you'll see the average VMG across all your maneuvers — a quick way to gauge your overall maneuver efficiency.

You can view maneuvers for one specific boat or all boats at once, and click through individual maneuvers to see how each one went. This makes it easy to find your best and worst tacks and understand what you did differently.

You can also use the Speed-colored track mode to visually spot speed loss and recovery during maneuvers on the map.

**Action Step:** Compare your fastest maneuvers with your slowest ones. What techniques are you using differently?

## One design coaching techniques

For more inspiration, continue on to [our interview of "Fuzz" (Grant Spanhake)](/blog/one-design-basics) on the blog. He goes into details on what he likes to focus on when coaching one-design groups.

## Pro Tip

Create a "speed journal" where you record your optimal angles and speeds in different conditions. Over time, this becomes your personal polars for your boat.

Now that you understand the key performance indicators, you're ready to move on to [analyzing your races](/sailing-data-course/race-setup) to extract even more valuable insights.


Tools of the trade

Set up race analysis in ChartedSails with mark placement, leg definitions, and start/finish lines. Turn raw GPS data into structured race insights.

Step 1: Highlight the Race on the Timeline



We train so we can win more races. Race analysis is a powerful feature in ChartedSails, and we've worked hard to make it intuitive and insightful.

We have prepared a short video covering this topic, or you can skip ahead to the written instructions below.

<iframe width="560" height="315" src="https://www.youtube.com/embed/1fBL8QFrPmY?si=mSb1OqJq1xk8y3eF" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>

## The Easy Path: Mark Pings and Race Timer

If you used the ChartedSails mobile app or a GPS device that supports mark pinging (like Velocitek or Vakaros), a lot of the setup is already done for you.

**Mark positions:** When you pinged marks during the race, ChartedSails knows where the marks are. You don't need to manually drag marks around — they're already in the right place.

**Start time:** If you used the race timer in the mobile app or your GPS device, ChartedSails already knows when the race started. No need to fine-tune the time with arrow keys.

This is why we recommend getting into the habit of pinging marks and using the race timer — it makes post-race analysis almost effortless.

## Manual Race Setup

If you didn't ping marks or use the race timer, you can still set up the race manually. ChartedSails makes this straightforward:

### Step 1: Highlight the Race on the Timeline
- Find the approximate beginning of **the start sequence**
- Click and hold to make a selection around the entire race

### Step 2: Define the Start Line and Time
- Click the "Create Race" button
- ChartedSails automatically positions the start line using your GPS data
- To adjust the line: hover over a mark and drag it to the correct position
- To adjust the start time: click the time field and use arrow keys for second-by-second precision

### Step 3: Define the Race Course
- Click "Add Mark" to define each leg of the race
- ChartedSails estimates mark positions from your track, but you can adjust as needed
- A red track indicates a mark rounding issue - move the mark until the track flows smoothly around it

## Common Issues and Solutions

When defining your race course, you might encounter these common challenges:

- **Problem:** Red track indicates boat not reaching the mark
- **Solution:** Move the mark closer to where your boat actually rounded

- **Problem:** Track loops around mark multiple times
- **Solution:** Ensure you're placing the mark at the correct location where you actually rounded it

- **Problem:** Start line appears at wrong angle
- **Solution:** Use the rotation handle to adjust the angle of the start line

## Pro Tip

Set aside 15-30 minutes after each race day to define your races in ChartedSails while the details are fresh in your mind. If you use the mark pinging and race timer features, this will take much less time.

## What's Next?

Now that you've set up your race in ChartedSails, you're ready to extract valuable insights from the data. Continue to the next section to learn about [turning your race into numbers](/sailing-data-course/race-analysis) that you can use to improve your performance.


Analyzing Your Races

Extract race insights from your GPS data in ChartedSails. Analyze starts, leg performance, VMG, and overall race metrics to find where you gain and lose.



Now that you've defined your race in ChartedSails, you can extract valuable insights from the data. This section will show you how to navigate through your race data and understand the key metrics that can help you improve.

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## Navigating Through the Race

To begin analyzing your race data:

1. Click on the orange bar on the timeline that represents your race
2. ChartedSails will zoom in on the race and filter out any other data
3. All the numbers and metrics will now be exclusive to the race you're analyzing

## Analyzing the Start

The race start is critical - often determining your position for the entire race. Click on the starting sequence and select the Performance tool to access these key metrics:

**Key Start Metrics:**
- **Speed at the gun** - The faster the better. Too slow may indicate you were stuck beneath another boat or being overly cautious
- **Time and distance to line** - Should be as close to 0 as possible without crossing early
- **Speed at the line** - Should match your target speed for the conditions

**Beyond the Numbers:**
- Did you start on the favored end of the line?
- Had you correctly identified the favored side of the course?
- Did your start strategy work as planned?

**Action Step:** Add a comment on the timeline about your start. Was it good? If not, what specific problem occurred? Identifying areas to improve is the first step toward progress.

## Leg-by-Leg Analysis

Click on each leg on the timeline to focus on that specific portion of the race:

For each leg, ChartedSails shows:
- Distance sailed
- Average speed
- Maximum speed
- VMG to the next mark

**Questions to Ask:**
- What side of the course did you sail on, and why?
- Did the wind rotate during the leg? Did you spot and react to shifts?
- How many maneuvers did you execute? (Generally, fewer is better, but not at the expense of missing shifts)
- Did you pinch because you tacked too early?
- Did you overstay a mark and waste distance?
- Are your speed, wind angle, and heel angle on target?

When you have multiple boats in your group, the leg-by-leg analysis becomes even more powerful. Compare your VMG, SOG, and TWA against the boats that beat you. Were you sailing a tighter angle but going slower? Or footing for speed but losing on VMG? These side-by-side comparisons pinpoint exactly where you gained or lost time.

## Overall Race Performance

After analyzing individual components, review your overall race performance:
- What was your average speed for the entire race?
- How does your total distance sailed compare to other boats in your group?
- How do your upwind and downwind VMG compare across the fleet?

## Session Reports

For a complete overview of your racing day, use the **Session Report**. Click the report button next to the session title to generate an easy-to-read summary of all the races in one day.

The session report includes:
- A weather overview for the day
- Average upwind and downwind performance for all boats across all races (excluding non-racing time, so you get a true picture of racing performance)
- Race-by-race breakdowns with a start lineup image showing all boats at the line, and a table comparing angles, VMG, SOG, distance, and time leg by leg for every boat

Session reports are a great way to quickly see the big picture and share results with your group.

## Pro Tip

Focus on extracting 1-3 specific lessons from each race analysis session. Make notes about these points and create a plan to improve them in your next race.

Now that you understand how to analyze your race data, continue to [sharing sailing insights](/sailing-data-course/sharing-insights) to learn how to collaborate with your crew and other sailors.


Your Race in Numbers

Share sailing data with your crew and training partners using ChartedSails. Learn best practices for debriefs, public links, and group collaboration.



Sailing improves faster when you learn together. Whether you're comparing tack angles with a training partner or reviewing race strategy with your crew, sharing data turns individual sessions into collective learning. ChartedSails makes it easy to get everyone on the same page.

## Groups: Share by Default

The best way to share data in ChartedSails is through [groups](/sailing-data-course/groups). When everyone in your group records their sailing, the data comes together automatically — no manual sharing required.

With a group, every member can:
- Replay any session that includes boats from the group
- Compare their performance side by side with other boats
- View session reports with fleet-wide breakdowns
- Access maneuver analysis across the group

### Group License

If you activate a group license, everyone in the group gets access to the advanced analysis tools — VMG breakdowns, maneuver stats, session reports, and more. This is the simplest way to make sure your entire team or training group can get the full picture, without each person needing their own subscription.

## Public Links

For sharing with people outside your group — or with anyone who doesn't have a ChartedSails account — you can create a public link.

1. Open the session you want to share
2. Click the **Share** button in the top right corner
3. Copy the public link

Send the link via email, WhatsApp, or any messaging app. Anyone with the link can replay the session, take measurements, and read the comments — no account needed.

Public links are great for:
- Sharing a session with a coach who isn't in your group
- Posting a race replay on a forum or class website
- Sending an interesting session to a friend

## Best Practices for Sharing

### For Skippers
- Share data immediately after racing while it's still relevant
- Highlight specific areas for crew members to focus on
- Use timeline comments to annotate key moments
- Ask specific questions to guide crew feedback

### For Crews
- Look at the data before your debrief session
- Compare your perception with what the data shows
- Prepare specific questions for discussion
- Focus on areas relevant to your role (trimmer, tactician, etc.)

### For Training Groups
- Make sure everyone is in the same ChartedSails group so data flows automatically
- Compare data across boats to identify different strategies
- Look for patterns in successful approaches
- Set up regular review sessions after racing days

## What Makes a Good Debrief Message

When sharing a session with your team, be specific about what to look at. Here's an example:

```
Team,

I've shared today's races. Please focus on:

1. Race 2, upwind leg 1: We had good speed but lost ground on the right side.
Let's discuss the tactical decision at 14:32.

2. Race 3, start: Our timing was perfect but our speed was 0.5 knots below
target at the gun. Check the trimming data.

3. All downwind legs: Compare our VMG with boat #42, who was consistently faster.

Please add your observations before our debrief tomorrow at 10 AM.
```

## Real-World Examples

We compiled a selection of [really compelling debriefs](/blog/compelling-sailing-debriefs) on our blog. Read it for some inspiration!

## Pro Tip

When sharing data with coaches or mentors, be specific about what you want feedback on. Generic "what do you think?" questions are less effective than targeted questions like "How could we improve our speed recovery after tacks in race 2?"

Now that you understand how to share your sailing insights, continue to [using video for improvement](/sailing-data-course/improving-with-video) to learn how to enhance your data analysis with synchronized video.


Sharing Sailing Insights

Combine video with GPS data in ChartedSails for deeper sailing analysis. Sync footage to your track and review technique, trim, and boat handling.



In the heat of racing, it's impossible to notice all the minute details that contribute to your performance. Video changes everything by providing an objective view of what happened.

With ChartedSails, you can synchronize video recordings with your sailing data, creating a powerful tool for improvement. Because the video is synchronized to your track, you can easily jump to specific moments — like the starting sequence of the second race, the first mark rounding, or the moment you hit your top speed.

## Adding Video to Your Session

### Upload from Your Phone

The easiest way to add video is to upload directly from the ChartedSails mobile app. Open the session, open the Media Gallery (top-right) and click +.
ChartedSails automatically shows you videos overlapping with the session. You can select multiple photos and videos.

**Important:** For automatic time synchronization, use the original video file from your phone. When videos are transferred through messaging apps or cloud services, the timestamp metadata is often stripped, which means ChartedSails won't be able to automatically place the video at the correct time on the timeline.

### Upload from Your Computer

You can also add video from the web app:
1. Open your session in ChartedSails
2. Drag and drop the files onto the replay (drop them on the map - or open the Media gallery and drag and drop them to Media).
5. ChartedSails will analyze the file and automatically detect the recording time
6. Your video will appear on the timeline at the correct position

### Supported Video Sources
- GoPro cameras
- iPhone and Android smartphones
- Most digital cameras with timestamp data
- Drone footage (with timestamp data)

### Cloud Storage

Videos are uploaded to the cloud, so they're available on any device — no need to carry files around or re-attach them when switching computers.

Each user gets **1,000 minutes** of video storage. Videos are automatically deleted after **90 days** to keep your storage available for new content. If you need a video beyond 90 days, make sure to keep a copy on your own device.

For teams and clubs we can offer more video storage and longer conservation. Contact us!

## Synchronized Playback

Once your video is on the timeline, the video and data replay are fully synchronized. You can navigate through the video and simultaneously see:
- Your boat's position on the track
- Performance numbers (speed, VMG, wind angle)
- Wind data
- Any other metrics you've enabled

Click anywhere on the timeline, and the video jumps to that exact moment. Click on the video timeline, and the track and instruments follow along.

## Making the Most of Video Analysis

Video is particularly valuable for analyzing:

### Starting Sequences
- See your positioning relative to other boats
- Analyze your acceleration and timing
- Review your crew's pre-start routine

### Mark Roundings
- Check your approach angle and positioning
- Analyze boat handling during the rounding
- Review crew coordination during sail changes

### Sail Trim
- Assess sail shape in different conditions
- Compare trim settings with performance data
- Identify opportunities for improvement

### Crew Work
- Evaluate movement and weight distribution
- Analyze crew coordination during maneuvers
- Review communication effectiveness

## Camera Placement Tips

- **Bow mount:** Good for starts and upwind sailing
- **Stern mount:** Ideal for crew work and downwind sailing
- **Mast mount:** Excellent for sail trim analysis
- **Crew-mounted:** Captures specific roles and perspectives

### Recording Settings
- Use medium resolution (1080p) for manageable file sizes
- Set wide-angle view to capture more of the boat and surroundings
- For longer sessions, consider using time-lapse mode

## Pro Tip

The most useful videos are the ones that capture your decision-making moments — starts, mark roundings, and tack/gybe sequences. If battery life is a concern, record only the races rather than the entire day.

Continue to [live coaching](/sailing-data-course/live-coaching) to learn how to use ChartedSails for real-time coaching on the water.


Using Video for Improvement

Use ChartedSails Live Coaching to follow sailors in real time from the coach boat. Take notes, record lineups, set up races, and debrief automatically.



ChartedSails' Live Coaching feature lets coaches follow their sailors on the water in real time, take notes, record lineups, and set up races — all from their phone on the coach boat. When the day is done, everything syncs automatically so the debrief is ready to go.

## Starting a Live Session

Live coaching works through [groups](/sailing-data-course/groups). To start a live session:

1. Open the ChartedSails app on your phone
2. Go to your group page
3. Tap **Schedule Session** and set the date and time
4. Your group members will see the scheduled session and can join when they head out

When a live session is active, a red dot and **Live** indicator appear in the app. All group members who are recording will have their data streamed in real time.

## The Live View

From the coach boat, you can see all your boats moving on the map in real time. For each boat, you can see:

- **Speed over ground** — how fast each boat is moving
- **Course over ground** — their current heading
- **True wind angle** — their angle to the wind
- **Heel angle** — how much the boat is heeling
- **Pitch angle** — fore-and-aft trim
- **Heart rate** — if the sailor is wearing a connected sensor

This gives you a complete picture of what's happening on the water without needing to be right next to every boat.

## Recording Lineups

Lineups are one of the most powerful coaching tools in ChartedSails. They let you capture a side-by-side comparison of two boats sailing on a parallel course.

### How Lineups Work

1. Identify two (or more) boats you want to compare — ideally sailing on the same tack, close together
2. Tap **SPEEDTEST** in the app and **START**
3. ChartedSails records the data from both boats, averaging the performance numbers in real time
4. Tap **Stop** when you're satisfied with the sample
5. Save the lineup with a descriptive name (e.g., "Boat 7 vs Boat 12 — upwind port tack")

The lineup captures averaged speed, VMG, wind angle, heel, and other metrics for both boats over that window. Because the data is averaged over several seconds, it filters out momentary fluctuations and gives you a reliable comparison.

### Using Lineups in Debriefs

Saved lineups appear in the session data and are available during the debrief. They provide concrete, objective data to support coaching points — instead of "I think boat 7 was pointing higher," you can show exactly how much higher, and whether that translated into better or worse VMG.

## Coach Notes and Races

During the live session, coaches have a dedicated view with tools to:

- **Add comments** — tag moments on the timeline with observations ("good shift response by boat 3," "boat 5 late to gybe at the gate")
- **Define races** — mark start times and legs directly from the coach boat, so the race structure is ready for analysis
- **Review lineups** — scroll back through the lineups you've recorded during the day

## End of Day: Automatic Sync

When sailors finish for the day and return to shore, the coach clicks 'End Session' and all the phones automatically upload the full-resolution track data to ChartedSails. The live data (which is lower resolution for real-time streaming) is replaced by the detailed recorded data.

This means the debrief session has the best possible data quality — full-resolution tracks, plus the coach's notes, races, and lineups — all organized and ready to review.

## Running an Effective Debrief

With live coaching data in hand, here's how to run a productive debrief:

1. **Start with the big picture** — use the [session report](/sailing-data-course/race-analysis) to review overall performance and conditions
2. **Walk through 3–5 key moments** — use your notes and the timeline to jump to teaching moments
3. **Show the lineups** — let the data speak for itself when comparing boat performance
4. **Replay critical situations** — use the track replay to show tactical decisions in context
5. **Keep it focused** — better to cover a few points well than to rush through everything
6. **End with action items** — give each sailor or boat specific things to work on

## For Large Events and Clinics

For coaching clinics with many boats, live coaching scales well:

- Have everyone join the same group before the event
- Schedule the session in advance so all boats are auto-assigned
- Use loaner GPS devices (like Vakaros or Velocitek) for boats that don't have their own
- The coach boat sees all boats on the map, regardless of how many are participating

## Pro Tip

The most effective coaches use live coaching not just for observation, but for real-time intervention. When you see something on the live view — a boat with too much heel, a boat that's slow out of a tack — you can radio them immediately with specific, data-backed feedback.

Continue to [using ChartedSails with AI](/sailing-data-course/ai) to explore your data in new ways with AI-powered analysis.


Live Coaching

Connect ChartedSails to AI tools like Claude and ChatGPT using our MCP integration. Ask questions about your sailing data in natural language.



> **This feature is experimental.** We're actively developing the AI integration and would love your feedback.

ChartedSails offers an MCP (Model Context Protocol) endpoint that lets you connect your sailing data to AI assistants like Claude or ChatGPT. Instead of clicking through the interface to find answers, you can ask questions in plain language and get answers drawn directly from your data.

## What Is MCP?

MCP is a standard protocol that allows AI assistants to connect to external data sources. Think of it as giving your AI assistant a direct line to your ChartedSails data — your sessions, boats, races, tracks, and performance metrics.

## Setting It Up

To connect ChartedSails to your AI assistant, configure the MCP endpoint:

```
https://api.chartedsails.com/mcp
```

### In Claude

1. Open Claude's settings
2. Navigate to the MCP connections section
3. Add a new connection with the ChartedSails endpoint URL
4. Authenticate with your ChartedSails account

### In ChatGPT

1. Open ChatGPT's settings
2. Look for the MCP or external tools section
3. Add the ChartedSails endpoint URL
4. Authenticate with your ChartedSails account

Once connected, the AI assistant can access your sailing data and answer questions about it.

## What You Can Ask

Here are some examples of questions you can explore:

- **"Which boat had the best start in race 1?"**
- **"What was my average VMG upwind in last Saturday's races?"**
- **"How does my heeling angles compare to other boats? Upwind? Downwind?"**
- **"Is my performance better in light air or strong air?"**

The AI assistant pulls the data from ChartedSails and presents it in a conversational format. ChartedSails provides context (weather, race course, break down of the track into upwind/downwind, etc) so that your AI assistant can quickly answer questions.

You can ask follow-up questions, request comparisons, or dig deeper into specific moments.

## Pro Tip

Ask AI to prepare reports for you. And when you have a format you like, ask it to save the report format as a skill so it can repeat the same thing for future events.

## A request

The ChartedSails MCP server is experimental! Let us know if you find it useful! If your AI agent struggles with something, let us know!

---

Congratulations on completing the Sailing Data Analysis Course! You now have the knowledge to capture, analyze, and share your sailing data effectively. Keep exploring and refining your skills, and don't hesitate to reach out to us if you have any questions.
