A real story from the A Scow racing community showing how GPS data prevented a protest hearing and improved fairness on the water.

During an A Scow race on Tuesday, May 27th, 2025, at the first windward mark, a tense situation unfolded. Two boats were approaching the mark when one boat tacked near the three-boat-length zone. What happened next could have easily led to a lengthy protest hearing and potential disqualification.

# The Situation

The initial disagreement was clear:

- One skipper believed the other boat had tacked inside the zone and failed to luff properly
- The other skipper thought they had completed their tack outside the zone
- Both crews were convinced they were right
- A protest room showdown felt unavoidable

## The ChartedSails Solution

Before heading to the protest room, both skippers reviewed their ChartedSails tracking data. What they saw surprised everyone—and changed the course of the conversation.

![GPS tracking data showing the tacking maneuver outside the three-boat-length zone](/assets/blog/justice-on-the-water/tacking-outside-the-zone.png)
_ChartedSails GPS tracking clearly showed the boat tacked outside the three-boat-length zone_

### What the data revealed:

- The boat in question had actually tacked outside the three-boat-length zone
- The GPS tracking showed precise positions and timing that were impossible to determine accurately in real-time during the heat of racing
- Both skippers' perceptions during the race had been incorrect

## The Resolution

Armed with objective data, both parties had an honest conversation:

**Skipper 1:** "I was wrong, you definitely got across head to wind before you entered the zone."

**Skipper 2:** "I was wrong too. I thought you luffed more than necessary, but now I see you matched us. If we had tacked in the zone, we definitely would have fouled you."

Since neither boat had actually fouled the other, they withdrew the protest. No time was wasted in the protest room, and everyone got a fair result.

## The Impact

The result? ChartedSails didn't just prevent a protest hearing—it improved fairness, understanding, and sportsmanship on the water.

- **No protest hearing needed** — saving time for sailors and race committee
- **Fair racing result** — based on what actually happened, not perceptions
- **Better sportsmanship** — objective data led to honest admissions and mutual respect
- **Learning opportunity** — both sailors gained insights into what really happened during a complex tactical situation

## The Power of Visual Analysis

One of ChartedSails' most useful features for protest analysis is that boats are drawn to scale on the map based on their registered length. Better yet, the system automatically draws the three-boat-length zone around marks—making complex scenarios easy to understand at a glance.

> "Using ChartedSails avoided a protest hearing for us. The track showed the other boat tacked outside the zone - we all thought they tacked in the zone. No harm, no foul."
>
> — John, A Scow racer

## Try ChartedSails – See Your Races Clearly

Ready to bring objective data analysis to your racing? [Get started today](https://chartedsails.com/sailing-data-course/) with GPS tracking and analysis that helps deliver fair, accurate racing results.

_Have a ChartedSails success story of your own? We'd love to hear about it - [share your story with us](mailto:hello@chartedsails.com)._


Justice on the Water: How ChartedSails Data Resolved a Racing Dispute

ChartedSails can load and display all the variables captured by your instruments.

## Introduction

Sailboats are complex machines, and skippers and crew rely on a wide range of instruments to help them navigate and optimize performance. Capturing sensor data for debriefing used to be reserved to professional teams but that is not the case anymore. Modern instruments can capture a vast array of variables, going far beyond just GPS position. This is a small revolution for sailing debriefs and we are here to help you make the most of it.

## ChartedSails

At ChartedSails, we provide specialized software that allows sailors to debrief their training sessions and races. Our software is designed to be user-friendly and customizable, allowing sailors to load, display, and analyze the data captured by the instruments on their sailboat. Sailors can work with a coach or alone to identify areas for improvement.

Over the past years we have seen a tremendous change in the capabilities of sailing GPS. There are now a wide range of devices able to capture your GPS data, but also your heel and pitch, tension in the rigging, boat speed in the water, heart-rate of the sailor, etc.

All of these variables and a few more are now available in ChartedSails. We have significantly rewrote how we process and handle data to be able to load and display these variables. And where ChartedSails used to limit data to one point per second, we are now able to take full advantage of the high resolution of the newer GPS units that capture up to 10 points per second. You get more detailed tracks, more precise analysis and it even runs faster than before.

## GPS Vendors and Variables Captured

Different GPS vendors offer varying instruments and sensors that capture different variables. Here's a look at some of the variables that can be captured by different GPS vendors:

- **Expedition Software** is the gold standard to capture data on a boat. ChartedSails will display most variables captured by Expedition.
    
    This includes:
    
    - The basics: position, speed and course over ground
    - Wind data: apparent and true wind direction and speed
    - Boat attitude: heel and pitch
    - Boat speed (in the water)
    - Rudder angle
    - Tension of the forestay
    
    To get all the variables, upload the CSV Expedition file to ChartedSails. There is no need to export or convert the files. All versions are supported.
    
- **Velocitek** offers GPS-based instruments that capture position, speed over ground, heading (real heading from a compass - not estimated from GPS course), heel and pitch. They also record pings of the marks and the precise start time of races. All will be visible in ChartedSails.
    
    To download from your Velocitek device, plug it into your computer and upload the VTK file to ChartedSails. To keep the maximum information, do not use a converter. 
    
- **Vakaros** devices capture position, speed over ground, heading and they can also capture wind data, boat speed, depth and load from load cells when connected to appropriate instruments on your boat. Pings of the marks and precise start time are captured as well.
    
    To benefit from all the capabilities of your Vakaros device you need to export the data in Vakaros format (VKX) from the mobile app and load it in ChartedSails.
    
- **Garmin Watches**: capture basic GPS-based variables (position, sog and cog)
and have the additional benefit of recording heart-rate. Using the lap button
on the watch you can mark precise moment in the race (start signal, beginning
of a drill, etc) and these will be visible as little markers on your track
in ChartedSails.

- **Cyclops Marine Load Cells**: capture the load on the rigging. They can be used in combination with other GPS units like Vakaros or Sailmon, but you can also export the data from their mobile app in CSV format and load it in ChartedSails.

- **Sailmon** devices capture position, speed and course over ground, heel,
pitch and when connected to appropriate sensors you will also get wind data,
and one load measurement for the rigging. To use data from sailmon devices,
export in CSV format. ChartedSails will recognize the file and load all the
variables included.

- **Capture from NMEA and NMEA2000 buses**
    
    ChartedSails can now also load directly from NMEA and NMEA2000
captures. We have tested with the **NKE Mini-Logger** and
**SignalK Server.** We will
continue to work on expanding this category.
    

This list is bound to change as existing devices become smarter and new ones
appear on the market. As we test new files and verify compatibility we will
update this page. 

If your device is not listed above or if your sensors are not supported, please
send us a note. Our policy is that if it can be recorded we want to support it.

## How to access these variables?

To keep the program simple, only the most essential variables are shown by
default in ChartedSails. To look at more variables, simply extend the size of
the instruments panel.

![Accessing extended variables in ChartedSails](/assets/blog/explore-further/expand-variables.gif)

## Wind data in ChartedSails

After much consideration, we decided to continue using the wind slider in
ChartedSails to set a general wind direction, and this is still the wind source
used to calculate your VMG and maneuver statistics.

There are two reasons for this :

1. When you are racing, you are optimizing to get to the next mark as fast
as possible. You effectively need to look at your Velocity Made Correct to
the course and that is what we give you now with the wind slider and VMG (and
yes we may end up renaming VMG to VMC). 
2. When comparing multiple boats,
differences in wind sensor calibration and local wind conditions would make
VMG comparisons useless if they were not based on one unique wind value for
everyone.

Let us know how you feel about these decisions. ChartedSails improves with your feedback.

## Data Visualization

Although it’s a huge step forward to have access to all these new variables,
there is a lot more we want to do in terms of data visualization. Stay tuned!

## Conclusion

The times where we had to argue for the importance of data in sailing are long
gone. With smarter sailing instruments and more sensors, we are adding more
dimensions to the GPS tracks and dramatically expanding the usefulness of the
data driven debrief.

As always, we are committed to turn data points into understandable and actionable
information that is useful to sailors at all levels.

We were amazed to see what you did with heel and pitch when we introduced
them about a year ago. We cannot wait to see what you will do with load-cells,
heart-rate and of course, wind data.

As always please keep in touch!




Explore further, dig deeper

A compelling race report drives performance improvements.

Debriefing with your crew is an essential part of improving your sailing performance. If you are lucky, you will take some time together, in person, after the race. When you run out of time, the debriefing might be just a phone call or an email.

Whatever you do, having some form of debriefing, is already a huge step up from doing nothing!

To provide some inspiration, we have rounded up some example of debriefings prepared by coaches and sailors. They all used ChartedSails to review their data and identify key points to focus on and then they used different techniques and tools to present the data and make it easy to share.

# Cilian Dickson - J/24 🇮🇪

Cilian is a J/24 sailor in Ireland, winner of the [J/24 Irish National Championship](https://j24ireland.ie/wp-content/uploads/2021/10/Results-2021.pdf) on his boat Headcase.

Cilian has a Velocitek ProStart on board and started using ChartedSails a few months ago.

Last month, he participated in a J/24 training event with the fleet and collected data from multiple boats to compare their performances. After loading the tracks in ChartedSails, he compiled key performance numbers from each race into a few Powerpoint slides.

![J24 training race day analysis](/assets/blog/compelling-reports/cilian-j24.png)
_One slide summarizes upwind performance of all the boats accross seven different races_

They chose to focus on:

- Starts: Distance to line and line speed
- Upwind performance (Distance sailed, average speed, average VMG)
- Downwind performance
- Tacking performance (using ChartedSails maneuver analysis).

In each slide he adds a few comments: is the fleet consistent? who is doing the best?

Take a look [at the full report](/assets/blog/compelling-reports/LRYC-J24-Training-10_April-Names.pdf) for some inspiration on your next race day! (Shared with permission from Cilian - boat names have been changed.)

# Ali Charlton - Elliott 770 🇺🇸

Ali is the skipper of Missy, a [Elliott 770](https://sailboatdata.com/sailboat/elliott-770) at the Oklahoma City Boat Club.

Ali also chose PowerPoint to collect key numbers from the day and share them with his crew. The first thing we noticed is that the slides include who was on the boat that day (important when your crew rotates). He also includes [wind data from USGS](https://waterdata.usgs.gov/ok/nwis/uv?site_no=07159550) which is a great idea.

The slides are very rich and combine screenshots of ChartedSails, tables from the maneuver analysis, USGS wind data and comments.

It's a lot but Ali managed to focus on a few important points in a one slide per day format. It looks good, and it's easy to share via email or social media.

![Ali's report on Missy Elliott 770 performance](/assets/blog/compelling-reports/ali-missy.png)
_Ali prepared a one page summary for each day. He shares them on Facebook._

# CISA 2022

[CISA Advanced Racing Clinic](https://www.instagram.com/cisasailing/) was held March 19th to March 21st at Alamitos Bay Yacht Club in Long Beach, California.

Three classes were presents: i420s, ILCAs and 29ers. Over 60 sailors and 10+ coaches.

For this event, we chose to use Google Docs to present the data. With a large number of boats we focused on "big picture": is the fleet consistent? when was the race won?

And when it was relevant, we zoomed in on specific moments: did you see the shift during this leg? What was the cost of missing the shift?

![Extract from ChartedSails performance report for CISA 2022](/assets/blog/compelling-reports/cisa-clinic.png)
_Focus on one upwind leg to discuss tactical decision-making and the importance of distance._

The resulting presentation is just a few slides per day which were reviewed during the debriefing. And when sailors had specific questions, we opened ChartedSails and zoomed in on the data!

# Conclusion

Some best practices from these three examples:

- Slides are a great way to present a debriefing and share it
- Find a few interesting things from the day and focus on them. Screenshots of ChartedSails, photos and other data (such as external wind data) are all great ways to illustrate your points.
- Make it easy to save and share: A one-pager summary of each race day will be a great way to review progress at the end of the season.

How do you debrief with your crew? With training partners? Let us know what are your best practices and send us your best reports!


Compelling Sailing Debriefs

Your Garmin watch is a perfect sailing companion. Always with you, already waterproof. Learn how to use it with ChartedSails!

What is always with you, has a great GPS and is waterproof? Your Garmin watch! It's the perfect companion when you are out sailing, wind surfing and kite surfing.

ChartedSails directly connects with your Garmin and synchronizes your sailing sessions. Next time you are on the water, simply start a new Sailing activity on your watch and your data will be already uploaded to ChartedSails by the time you get back to the dock.

## Setup Garmin synchronization

On your ChartedSails dashboard, [click on the menu button in the top right
corner and select "Garmin"](/profile/garmin). It will ask you to Login to your Garmin Connect account. Simply follow the instructions.

_**PRO TIP:** We have noticed some issues between Chrome and Garmin Connect.
Garmin is aware and they are working on it. If you see an infinite spinner when
connecting Garmin to ChartedSails, visit [Garmin
Connect](https://connect.garmin.com) first and log out. Then try again._

## Start a Sailing activity

ChartedSails will **ONLY** synchronize Garmin activities labeled as "sailing"
(this is to avoid polluting your ChartedSails account with other activities than
sailing).

Some Garmin watches offer Sailing out of the box, after selecting the "Start Activity" button.

If your watch does not offer this activity, you can easily add it directly on the watch:

- Navigate to your watch main menu
- Select "Settings"
- Select "Activity Profiles"
- Select "Add New"
- The watch will ask you what type of sport to base this new profile on. Select "Running".
- Select a color
- Type the new activity name: "Sailing"
- Confirm

Now when you want to record a sailing activity, click on the Start Activity button, scroll to Sailing and select it.

## Synchronization

Every time you record a new sailing activity, it will be saved by your Garmin
watch then transmitted to your phone. When your phone receives it, ChartedSails
is notified and automatically processes it. Youy now have direct access to your
sailing replays.

That's it! [Let us know](mailto:ahoy@chartedsails.com) if you have any question or feedback on this new feature!


Take your Garmin Watch sailing

Learn one-design sailing fundamentals with coach Fuzz Spanhake. Master sail trim, heel angle, and sailing modes to improve your racing performance.

“Fuzz” is a very respected coach and one of the first users of ChartedSails. I sat down with him recently to discuss the basics of one-design sailing and coaching.

<i>**Thomas - ChartedSails: I know you coach a lot of Etchells and J70s. Can you tell me what are the first things you focus on when you start working with a new boat?**</i>

The basics are always the same and as coaches we end up spending most of our time working on sail trim, heel angle and sailing the boat properly.

With sail trim, you need to become familiar with different twists of the mainsail and learn to recognize the difference between a medium twist, tight twist and ease twist. This is most easily seen from a coaching boat and with photos or videos. Even by yourself, you can take pictures and associate them to different marks on the main sheet to learn what twist you get from each setting (<i>Thomas: for help analyzing sail pictures, check out <a href="https://www.thesailcloud.com" target="_blank">thesailcloud.com</a>.</i>).
If you can practice with another boat, have one boat stay consistent and the other boat change trim. This is the most effective way to learn and see the impact of different settings.

When it comes to heel angle you always want to keep the boat as flat as possible.
While we are on the subject of crew weight, you can also play with fore and aft trim: have the crew move around the boat. More than bow up or bow down, you are looking for the least disturbance in the water behind the transom.

Sail trim and heel angle come together to make sure that you are sailing the boat properly for the mode that you are trying to sail in.

<i>**Thomas - ChartedSails: I have heard you mention modes a lot. What are the most common sailing modes and when should we use them?**</i>

There are three basic sailing modes that you need to be comfortable with when racing. You need to practice them so you can quickly switch to one and sail it effectively.

The first mode is high mode where you are trying to sail as high as possible. You would use this on the start to identify an open lane and take it. This is also useful if you are below someone and need to give them some room to tack. In this mode the telltales are not flat, they are typically flying up 45º to 60º.

The second mode is VMG mode. That is where you are trying to go as fast as possible towards the next mark. This is your default mode.

And finally there is fast mode. You would use this after tacking on top of someone to lock them in position or to quickly switch from one side of the course to the other side. In this mode you are sailing a bit lower, your VMG is not as good but your boat speed is the highest.

<i>**Thomas - ChartedSails: What should people look at in their sailing tracks?**</i>

The GPS track gives you a chance to measure your speed, your sailing angles and your VMG (In ChartedSails, just bring your mouse over the track to get that information). Except when you have a specific tactical goal you should be sailing in your best VMG mode. Look at your VMG leg by leg, your sailing angles and verify that you were sailing best VMG. If you can collect data from different boats this will become even more obvious.

<i>**Thomas - ChartedSails: And what else would you look at?**</i>

There is so much to look at! The tools are here and the first thing is to use them. After modes I would look at some tactical decisions:

- Did you pick the right side of the gates after the first downwind leg? How did you execute this turn? For this, I would recommend looking at videos too because your track will not show you what the other boats were doing.
- Did you decide to attack or defend in the second beat? Is this reflected in the data?
- If you chose to switch sides, did you effectively sail fast mode from one side to the other? How much height did you lose in the process?

And really, as much as possible, ask yourself, the driver, the trimmer: what were we trying to do? Did we actually do this? These questions will help you progress a lot, and the sooner you do it after sailing, the more effective the debriefing will be.

<i>**Thomas - ChartedSails: Thanks a lot “Fuzz”! If you have questions for “Fuzz”, head over to his website at [gsyachting.com](https://www.gsyachting.com/).**</i>


One design coaching basics with Fuzz

Learn how to use ChartedSails to analyze the race leg by leg.

We just updated ChartedSails interface and added the most requested feature of 2020, race analysis leg by leg.

To demonstrate how this works we made two short videos.

### 1 - Setup the race

This first video covers:

- How to highlight and save races
- How to set the marks
- How to set the wind direction

<iframe width="896" height="504" style="width: 100%" src="https://www.youtube.com/embed/1fBL8QFrPmY" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

### 2 - Analyze the race

Learn how to:

- Compare VMG of boats sailing on similar tacks
- Measure distance sailed, average speed and time leg by leg
- Understand how the race was won

<iframe width="896" height="504" style="width: 100%" src="https://www.youtube.com/embed/Y62GZ39fedA" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>


Tactics, Performance and Maneuvers - Analyze the race leg by leg

Learn how to use GPS pinging for accurate start line analysis. Improve your racing starts by tracking time, distance, and speed with modern sailing GPS devices.

Good starts are all about time and distance. If you sail in a class that allows pinging the line, you ping the line.

What you may not know is that modern sailing GPSs record all your pings and start times in the files with your sailing track. ChartedSails can display these events and use them to tell you how well you did.

## Pings and race timers

When you upload a new track to ChartedSails, all the events of the day are displayed on the chart.

Move your mouse over the markers to see what type of pings (PIN / BOAT) they represent and when they were recorded.

![ChartedSails can display all race events recorded by your GPS.](/assets/blog/start-analysis/race-events.png)

## Use the pings for race analysis

To use the recorded pings for race analysis, make a selection on the timeline to highlight the race that you are interested in.

The CREATE RACE button will show a GPS icon to inform you that this race will use the marks you pinged while sailing.

![Highlight the race to create a new race](/assets/blog/start-analysis/make-selection.gif)

To finalize this race, set the other marks ([watch video][setup-race]) and confirm the new race.

## Start Analysis

To analyze the start, simply move your mouse over the track between the start and the line. ChartedSails shows you key information about your start:

![Hover over the track to see start analysis data](/assets/blog/start-analysis/hover-for-start-analysis.gif)


 - **Distance To Line**

 	How far your boat was from the line when the gun fired (this is the distance you had to sail to reach the line, not the shortest distance to the line).

 - **Time To Line**

   How long it took your boat to reach the start line.

 - **Speed over ground at the gun**

   How fast your boat was sailing when the gun fired.

 - **Speed over ground at the line**

   How fast your boat was sailing when it crossed the line.

## Compatibility

All users can benefit from Start Analysis. You just need to [setup the race][setup-race] for this feature to work. 

To see the pings and the race timer events on the map you need a compatible GPS. ChartedSails currently supports the new Velocitek Prostart and the Vakaros Atlas. If you would like to see support for another GPS, please [contact us][contact].

[setup-race]: /blog/tactics-performance-maneuvers-analyze-the-race-leg-by-leg
[contact]: mailto:ahoy@chartedsails.com


Use your GPS to ping the start line

Compare the shapes of two J/70 gybes and improve your downwind technique.

The corollary to Ed Baird’s _“Losing a quarter of a boatlength less than your
opponent in each tack means one length gained in a four-tack beat.”_ Must be
_“losing a quarter of a boatlength less than your opponent in each gybe means
one length gained in a four-gybe run.”_ (from [Staying on Target](https://www.sailingworld.com/staying-on-target/)).

In many modern classes a four-gybe run might be a lot of maneuvers but you
get the point; fractional boat lengths matter.

Just like [we learnt from good and bad
tacks](/blog/learn-from-sailing-data-good-and-bad-tacks) looking at the shape
of the turn and the speed through the maneuver can tell us a lot about a
gybe. Again, this is very easy to do using ChartedSails and the data from
your [Velocitek ProStart](https://www.velocitek.com/pages/prostart). Using
the speed colored tails, boat card and stripchart, quantitative and
qualitative analysis is easy.

Once again, you can look at each gybe in three parts: entry, turn and
exit:

- For the entry you want to see that you are on your VMG angle and traveling
  at target speed into the turn.

- During the turn you want to see that the momentum is carried downwind (and
  down the course) and you have a nice smooth turn (consistent rate of turn).
  Just like tacks the rate of turn will vary with wind and sea conditions and
  generally speaking, you want a consistent rate of turn in each maneuver.

- For the exit you want to see that the turn stops at a good acceleration or
  speed build angle, the boat is able to accelerate straight away and there is
  no searching for exit angle.

### Follow Along!

For this blog post, we invite you to follow along on your computer. We will
be looking at the first gybe of the race. Note that most of the tools we use
here are only available on the computer version so you might want to wait
until you are home to try this.

1. Open the <a href="/session/j70-davis-island" target="_blank">J70 racing at Davis Island</a> session
2. Click on the "First gybe" bookmark (in the timeline) to focus on the first gybe.
   ![Open the "First gybe" bookmark](/assets/blog/downwind-technique/open-bookmark.gif)

## Entry

Green is S-ing and you can see (switch to the speed-colored tail) that the
speed is going up and down . This is a topic that is probably worth another
post all to its own. Stand by for that...

Approaching the turn you see Green get slow (from 11kts down to 7kts). To rebuild speed, they head
up and then gybe. This may have been traffic related but it is not ideal if
you are in open water.

![Use the colored trail button to quickly identify slowdowns and acceleration.](/assets/blog/downwind-technique/entry.png)

Pink, on the other hand, is steering a much tighter groove. The course and
speed vary much less than Green. Going into the gybe there is little or no
change in course and speed.

Using the ChartedSails boat cards we see Pink enters at 10.4 of boatspeed and
7.6 VMG.

![Pink has a steady course and the best VMG into the gybe.](/assets/blog/downwind-technique/pink-entry.png)

Green enters at 10.9 knots with 7.2 knots of VMG. Green has an
additional 0.5 knots of boatspeed but 0.4 knots less VMG. Quantitatively we
can see that the turn up was too large and the boat is sailing too high going
into the gybe.

![Green zigzags into the gybe, sails faster but with a lower VMG into the gybe.](/assets/blog/downwind-technique/green-entry.png)

### How does the turn up before the gybe impact your race?

First, you lose gauge down the course. You’re sailing across the course
instead of down it, towards the leeward mark.

Second, it is harder to judge your turn and your exit angle. Because you’ve
just headed up you can more easily get lost in the turn and misjudge your
exit angle. If you’re a numbers person, and you do some quick math to pick
your exit angle, you might pick an angle that is too low because you were
artificially high when you started the gybe.

Third, momentum. Because you just headed up, you now need to turn through a
greater number of degrees. This means you’ll use more rudder (which acts as a
brake) or you’ll be turning for a longer period of time. Either way, you’ll
carry less momentum out of the turn.

## Turn

Green has a much sharper turn. With the quick turn down Green enters the gybe with 9.8kts of boatspeed and is doing 8.4 knots
of boatspeed (also VMG) at dead-downwind and they get there fast. At a
glance these figures appear great but the turn happens so quickly that the
benefit from the bear away is short lived. What happens next is that the rate
of turn remains high and the speed and VMG plummet.

![Green enters fast into the gybe but slows down considerably](/assets/blog/downwind-technique/green-gybe.png)

A fast turn also makes it tough on the crew who have less time to do their
sail handling and boat handling through the turn. And because everything is
happening so quickly, the driver has less time to pick their exit angle.

Pink has a nice smooth turn. Their speed and VMG are not as high as Green
but their low speeds are much higher as they are able to carry more momentum
through the bear away into the turn and down the course.

![Pink carries more momentum through the gybe](/assets/blog/downwind-technique/pink-gybe.png)

Using the ChartedSails boat card we can see that Green travels 94 meters in
22 seconds and Pink travels 99 meters in the same time (centered around their
respective gybes).

## Exit

Green had a wiggle up then down then back up searching for the exit. While
minor, all of this driving loses gauge, burns speed and makes things more
challenging for the trimmers.

![After the gybe, Pink is sailing much faster](/assets/blog/downwind-technique/exit.png)

Pink exits straight, accelerates and then bears away (likely as a puff hits).
Looking at the track we see a nice steady course out of the gybe. There is no
searching for the exit angle. Using the heat mapped track and the speed
stripchart you see the speed bottoms and turns as the boat accelerates and
then the big acceleration and bear away as they link up with the next puff.

Moving the mouse over the track, we can see that after the gybe, Pink's VMG
is 5.7kts while Green who is sailing higher and slower only has a VMG of
3.5kts.

## Conclusion

Driving a sailboat well takes an incredible amount of practice and focus. It
is way easier to be a Monday-morning quarterback and pick apart maneuvers in
a debrief than it is to execute them well in the heat of battle. But
continuous improvement and learning is the name of the game.

Using ChartedSails makes it easy for sailors and coaches to debrief a day of
sailing. The more you can learn from a day on the water, the better you can
be the next day.

Here we looked at data from two different boats and looking at one maneuver
we can learn a lot about technique and ways to improve. If you have not done so already,
[open up this J70 replay](/session/j70-davis-island) and take a look at the next gybe.

[Recording sailing data is
easy](/blog/eight-ways-to-record-gps-tracks-of-sailing-drills-and-regattas),
upload your own data and get a friend in your fleet to do the same to start
the group learning in this extended off season, this sailing season, and
beyond!


Learn from sailing data: Downwind Technique

Looking at the shape of the turn and the speed through a tack can tell us a lot about the maneuver. Learn how to analyze your tacks.

> Losing a quarter of a boatlength less than your opponent in each tack means one length gained in a four-tack beat.
>
> _Ed Baird - [Staying on Target](https://www.sailingworld.com/staying-on-target/)_

Looking at the shape of the turn and the speed through a tack can tell us a
lot about the maneuver. This is very easy to do using ChartedSails and the
data from your Velocitek ProStart or other GPS logger. ChartedSails makes the
quantitative and qualitative analysis of our maneuvers very simple.

You can look at each tack in three parts: entry, turn and exit:

- For the entry you want to see that you are on a close hauled angle and the
  boat was at target speed going into the turn.

- During the turn you want to see that the momentum is carried into the wind
  and the rate of turn is consistent. The rate of turn will vary with the
  conditions (wind and sea state). But generally speaking, you want a
  consistent rate of turn in each maneuver.

- For the exit you want to see that the turn stops at a good acceleration or
  speed build angle, the boat is able to accelerate straight away and you are
  close to a close hauled angle.

Let’s take a look at a couple tacks recorded on a Melges IC37!

## First, a good tack

In this tack we have a nice smooth turn and the speed bottoms and increases
on approximately the same angle out of the tack. This means the momentum is
carried through the turn. We can see the low speed point and the speed
carried through the turn using ChartedSails’ speed-colored tail.

![First tack overview](/assets/blog/tacks/tack1-overview.gif)

### Entry

Using ChartedSails, we average 10s of data before the tack (notice the blue
background on the boat card when averaging) to see see our boatspeed and VMG
going into the maneuver.

![First tack - Entry](/assets/blog/tacks/tack1-entry.png)

Looking at the boat polars for our Melges IC37, we can see that we are a
little low and fast wth 7.2 knots of boat speed but we are not far off (we
had about 10 knots of wind that day). We’re moving up the racecourse well
with 5.3 knots of VMG.

[![Boat polars for Melges IC37](/assets/blog/tacks/ic37-boat-polars.png)](https://static1.squarespace.com/static/59b2e4ee9f8dce4dd22b7033/t/5dc02f57054df40f0c446f13/1572876119916/IC37+Class+Targets+%28Melges37_Polars+masttop+height_rev1%29.pdf)
_Designer provided boat polars for our Melges IC37. Click to open._

### Turn

Looking at the track we can see a nice smooth carve up into the wind as
evidenced by the maintained momentum. The boat card shows that we’re still
traveling 6.8 knots at 100% VMG! We only drop 0.4 knots of boatspeed and our
VMG has jumped 1.5 knots!

![First tack - Turn](/assets/blog/tacks/tack1-turn.png)

### Exit

Looking at the track we see a nice steady course out of the tack. There is no
searching for the exit angle. Using the heat mapped track and the speed
stripchart you see the speed bottoms and turns as the boat accelerates.

![First tack - Exit](/assets/blog/tacks/tack1-exit.gif)

## Tack 2 - A wild one!

Looking at the track, we can see right away that this tack does not have the
same nice smooth shape of tack 1. The shape is more complex with a tightening
radius as the turn progresses.

![Second tack - Overview](/assets/blog/tacks/tack2-overview.gif)

### Entry

Looking at the track and the boat card, the entry is pretty standard. The
course is relatively straight and the boatspeed is good.

![Second tack - Entry](/assets/blog/tacks/tack2-entry.png)

### Turn

The turn into the wind is good and the momentum is carried up the course.
However the speed is not carried as well into the wind. Using the boat card,
we can see that we lose 2.4 knots of boatspeed.

![Second tack - Turn](/assets/blog/tacks/tack2-turn.png)

### Exit

Here’s where things get exciting! Looking at the track you can see the radius
of the turn tightening in the later stages of the tack. The boat continues
turning, well past a good exit angle. We measure with ChartedSails a TWA as
high as 68° for a moment. Using the boat card we can easily compare the exit
angle with the entry angle. The entry is 43° and the exit peaks at 68° or ~25°
of over tack.

![Second tack - Exit](/assets/blog/tacks/tack2-exit.png)

Why is this bad? Won’t the boat accelerate back quickly at 68° TWA?

Yes, the boat will accelerate quickly at 68° TWA, but it is accelerating
across the course and we lose gauge up the course (see image below).
Additionally this means the sails need to get eased to a reaching angle and
then retrimmed to an upwind angle as the boat course corrects.

Quantitatively, using ChartedSails boat card, we can see that the VMG at this
exit angle is 1.8 knots with a boatspeed of 5.0 knots. Compare that with just
a few seconds before a VMG of 3.8 knots with 5.3 knots of boatspeed.

![Second tack - Distance lost to the wind](/assets/blog/tacks/tack2-exit-dlw.png)

## Conclusion

Using ChartedSails makes it easy for sailors and coaches to debrief a day of
sailing. The more you can learn from a day on the water, the better you can
be the next day.

Adding training partners’ and friends’ tracks to ChartedSails gives you even
more to talk about and even more learning opportunities as a group.


Learn from sailing data: good and bad tacks

Learn how to use ChartedSails to analyse your sailing drills and regattas.

We built ChartedSails to enable more sailors to use data in their training
and tuning routine. Every new feature is carefully designed to be easily
accessible and intuitive to use.

If you are not recording yet, make sure to read our [howto record sailing
sessions](/blog/eight-ways-to-record-gps-tracks-of-sailing-drills-and-regattas) guide.

Keep reading to learn about the key tools to analyze your sailing drills and regattas.

## 1. Navigate your replay

When you open a sailing session in ChartedSails you will find a large
timeline at the bottom of your screen showing your speed (in Knots) over
time. By moving your mouse over the graph you can easily see where the boats
were at a given time and what was their speed and course at that time.
![ChartedSails timeline](/assets/blog/analysis-howto/timeline-navigation.gif)

Click on the graph to move the playhead.

## 2. Control the playback

The `Play` button on the left of the graph launches the replay. Click on the
replay speed to switch between different speeds.

![Control replay playback](/assets/blog/analysis-howto/timeline-play.gif)

## 3. Know your tail modes

ChartedSails can display boat tracks in different ways:

- **Track colored as a function of speed**

  ![Track colored as a function of speed.](/assets/blog/analysis-howto/tailmode-speed.png)

  This is the default mode if you have only one boat in your replay. The
  color scale is displayed on the side of the screen and is automatically
  adjusted to the maximum speed of your boat. In this mode, you can easily
  notice fast segments and slower segments. You can also very effectively
  look at tacks and gybes to see how long before the manoeuver you started
  losing speed and how fast you got back to your previous speed on the other
  tack.

- **Full tail**

  ![Full track mode](/assets/blog/analysis-howto/tailmode-full.png)

  In this mode, each track is drawn in the color of the boat (see the boat
  cards in the top left corner to get the name of your boat). This makes it
  easy to compare trajectories and evaluate your tactical choices during a
  race. This is the default mode when you have multiple boats in a replay.

- **Partial Tail**

  ![Partial tail mode](/assets/blog/analysis-howto/tailmode-partial.png)

  In this mode, ChartedSails shows 10 minutes of sailing tracks for each
  boat. This makes it easier to look at long replays when boats have sailed
  over their tracks multiple times. Another way to deal with long tracks is
  to zoom on the part you are most interested in. Keep reading to learn how
  to do this!

## 4. Set up your wind

ChartedSails can help you measure the True Wind Angle and the Velocity Made
Good so you can effectively compare different tacks. Without a precise source
for wind, we rely on an estimate of the wind direction.

To set the wind direction on a session, click the 'Set Wind Direction` button
and rotate the map using the compass until the wind is coming up from the
top. It's usually very easy to find the wind direction just by looking at the
tracks.

Once the wind direction is set, ChartedSails will show True Wind Angle and
Velocity Made Good (your speed in the direction of the wind).

![Set wind direction](/assets/blog/analysis-howto/setwind.gif)

## 5. Use the time bracket tool for precise measurements

The big picture is interesting but you will often need to zoom in on specific
moments to isolate a leg, a manoeuver or even a complete race and take
measurements.

To zoom on the timeline, click on the graph and while keeping the mouse
clicked, drag your mouse on the graph. As you drag the mouse, the tracks
adjust to show precisely what you are selecting. When you are satisfied with
your selection, release the mouse button. The timeline will zoom
automatically to your selection.

If you need to adjust the selection, you can position the mouse on the
beginning or end of the selection and adjust the edges. Finally, click on the
X mark in the top right of the selection to close the active selection.

![Select on the timeline](/assets/blog/analysis-howto/timeline-selection.gif)

When a selection is active, the boat cards show average speed, total distance
sailed, average true wind angle and average velocity made good for each boat.

![Boat cards with selection active](/assets/blog/analysis-howto/boatcards-selection.png)

## Conclusion

Now that you know all the basic tools required to analyze your sailing
sessions, we suggest you take a new look at [your sessions](/) or one
of the demos available on the homepage and try answering the following
questions:

- What is your typical tack-to-tack angle?
- Which boat sailed the shortest distance in the race?
- What is the best VMG you were able to sustain for at least a minute upwind?
  What was your true wind angle? And what was your boat speed? This can now
  become your target boat speed (for similar wind conditions).

If you have any questions, just hit the blue chat button or [send us an
email](mailto:ahoy@chartedsails.com).


Five tools to analyze your sailing tracks

Discover 8 ways to record GPS tracks of your sailing drills and regattas.

Recording all training sessions, drills and races is the very first step in using
data to improve your sailing performance. There are many ways to do it and
no excuses for not starting today!

## Record sailing sessions with your phone

We all have smartphones and many of us already take them on the water. The
wetter the dinghy the more complicated it gets but [waterproof
pouches](https://amzn.to/2T5JD6N) are cheap and will protect your phone from
splashes. For more serious dunking, [the Pelican
cases](https://amzn.to/2v2amsN) are always a solid option, come with strong
hooks to tie them to the boat and do not interfere with the GPS signal.

For iOS users we recommend `Open GPX Tracker`. It is free, no ads and lets
you easily export GPX files that are compatible with ChartedSails. For higher
accuracy, set the "Activity Type" to Fitness in the settings.

[![Open GPX Tracker for iOS](/assets/blog/record-howto/opengpx-tracker.png)](https://apps.apple.com/us/app/open-gpx-tracker/id984503772)
_Click the image to download OpenGPX Tracker for iOS._

### And for Android users

For Android users, we recommend `GPS Logger`. It is also free, without ads
and offers easy export of GPX files.

[![GPS Logger](/assets/blog/record-howto/gpslogger.png)](https://play.google.com/store/apps/details?id=eu.basicairdata.graziano.gpslogger)_Click the image to download GPX Logger for Android._

For both iOS and Android users, the easiest way to collect the files is to
email them to yourself. A slightly more advanced option is to save them to a
cloud disk storage like Dropbox, Google Drive or iCloud.

Now of course there is always a risk involved with expensive phones on
dinghies and if you do not want to take that risk - or make your students
take it, you might consider a dedicated sailing GPS.

## Velocitek GPS

Velocitek is extremely well known in the dinghy world and all their GPSs
record data on an internal memory. We have extensively tested ChartedSails
with both the ProStart and the SpeedPuck.

[![Velocitek ProStart and SpeedPuck](/assets/blog/record-howto/velocitek-gps.png)](https://amzn.to/2x4lsy2)
_The Velocitek Prostart and the SpeedPuck are great options to record sailing tracks._

To view your data in ChartedSails, simply connect the Velocitek device to a
computer via USB and use the Velocitek Control Center. After downloading a
track, the program will offer the option to "Open in ChartedSails" directly.

It is the easiest way to get your data from the water to the computer.

![Velocitek Control Center offers the option to open tracks in ChartedSails](/assets/blog/record-howto/velocitek-controlcenter.png)

## Vakaros Atlas

[![Vakaros Atlas](/assets/blog/record-howto/vakaros.jpeg)](https://www.vakaros.com)

The Vakaros Atlas now supports logging of all sailing sessions. At the end of the day, the data is available for download via the Vakaros mobile app and you can upload it directly to ChartedSails from your phone using the mobile browser.

For more information on the new firmware which supports logging, [checkout the Vakaros blog](https://www.vakaros.com/blog/2021/5/20/telemetry-logging-its-here).

## Use a Garmin running watch to go sailing

**Update Nov 2021**: ChartedSails now supports automatic synchronization with
Garmin. [Click here for more details](/blog/take-your-garmin-watch-sailing).

Garmin offers a plethora of sport watches and we like to mention them here
because there is a good chance you or someone around you already has one. If
you don't, you can pick up the entry level [Forerunner
25](https://amzn.to/2WloKaT) for ~\$95 on Amazon and it will do the job just
fine.

Just record your sailing sessions as a "Run" or "Cycle" activity and when you
are done they will automatically sync to your phone and to the web via Garmin
Connect.

To export the track and use it on ChartedSails you will need to visit [Garmin
Connect website](https://connect.garmin.com/modern/activities) and go to the
"All Activities" page. From there, select your sailing session (click on the
title) and on the details page click on the Gear icon in the top right and
'Export to GPX'.

![Export Garmin sailing activities as GPX files for
ChartedSails](/assets/blog/record-howto/garmin-export.gif)

Garmin GPX files work perfectly on ChartedSails and this process works with
all Garmin activity watches.

## Wear that Apple watch on your dinghy!

[Apple says the Apple Watch 2 and newer models can be use for ocean
swimming](https://support.apple.com/en-us/HT205000) but not for scuba diving
or water skiing. Depending on the type of sailor you are, you will need to
decide if you want to take that risk.

Open GPX Tracker, our recommendation for iOS also has an Apple Watch version,
and it is also completely free. We recommend it.

[![Open GPX Tracker for Apple
Watch](/assets/blog/record-howto/applewatch.png)](https://apps.apple.com/us/app/open-gpx-tracker/id984503772#?platform=appleWatch)

## Take your GoPro sailing

<iframe width="896" height="504" style="width: 100%;" src="https://www.youtube.com/embed/fx_4DD_ksP8" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

There is no doubt that GoPro cameras are extremely cool. Did you know that
all [GoPro cameras](https://amzn.to/2WmeXkU) since the GoPro 5 record GPS
data?

**ChartedSails will automatically extract GPS data from the video.** Just click Upload, select your video file and let the magic happens. To save time and bandwidth, the GPS data is extracted on your computer and the full video file is not uploaded. Repeat the operation for each video file and you will have your full session.

And if you are not sure how to mount the GoPro on your boat, Jon Deutsch has
[some suggestions for you on his
blog](https://jdeutsch.com/2012/10/26/laser-gopro-mount-locations/).

## Use Expedition Sailing with ChartedSails

[![Expedition Navigation and Sailing
Software](/assets/blog/record-howto/expeditionmarine.jpg)](https://www.expeditionmarine.com/)
_Expedition Sailing is a popular Windows application in the sailing world._

Ok this one might not apply to a lot of dinghies but if you also sail on
bigger boats you might be interested to learn that ChartedSails can directly
open the ".csv" files recorded by Expedition Sailing.

## Live tracking of dinghy sailing

We are testing a number of live trackers with top-level athletes. The data is
available to the coach in realtime and there is no need to physically connect
to the GPS at the end of the day to prepare the debrief.

If you are a coach
interested in adding live tracking of sailboats to your tools, [contact
us](mailto:ahoy@chartedsails.com) and we will get you set up.

## What are we missing?

What other tools are you using or would you like to use with ChartedSails?
[Send us an email](mailto:ahoy@chartedsails.com) and we will make sure to add
support for it and update this list.

Now that you know how to record sailing data, make sure to learn how to use [our tools
to analyze your sailing sessions](/blog/five-tools-to-analyze-your-sailing-sessions).


8 ways to record GPS tracks of your sailing drills and regattas

Whether you are a coach working with a large fleet or a solo skipper training
with a partner, sharing your replays is a 

Whether you are a coach working with a large fleet or a solo skipper training
with a partner, sharing your replays is a great way to extend the practice
and make sure you are getting the maximum value from your time on the water.

## Share your sailing sessions

To share a session, simply click on the share button and type the email address of the person you want to invite. Add a message if you would like and click send. That's it!

![Howto share a sailing session](/assets/blog/share-howto.gif)

## Sharing like a pro

If you need to share with a lot of people, a WhatsApp group or to post the
replay on your blog, you can simply copy the URL in the navigation bar and
send it. Anyone with the URL will be able to watch the replay but they will
not be able to edit it.

## A note on data and privacy

All the data you upload to ChartedSails is **private** and cannot be
discovered by search engine or by other users.

However, if you post the link to another website, a forum or a social
network, search engines will discover the data and may show it in search
results. If that happens and you need us to "hide" something, just [reach
out](mailto:ahoy@chartedsails.com) and we will help you.


Share sailing sessions with the crew

Inevitably you will soon be [recording](/blog/eight-ways-to-record-gps-tracks-of-sailing-drills-and-regattas) more data 

Inevitably you will soon be [recording](/blog/eight-ways-to-record-gps-tracks-of-sailing-drills-and-regattas) more data than you need. Often you will only care about a few hours in a full day recording. Another day the GPS will be left on when the boat is on the freeway.

## Trim a sailing session

To help you focus on the data that really matters to you, you can easily trim
your sailing tracks in ChartedSails:

- Click Edit in the top right corner
- Move the left and right bars on the timeline to select the data you want to focus on
- Click save to record this change

### What happened to my data?

When you trim a session the data is not removed, it's just hidden away and
ChartedSails will not use those hidden moments to calculate averages and
other stats. If you ever need it back, you can simply click trim again and
re-extend the session.

## Dividing a session into multiple races

Very often you will have one file with multiple interesting moments (speed tests, races, etc).

ChartedSails allows you to very easily bookmark these moments to get back to them later. To make a bookmark, start by making a selection on the timeline (click and hold your mouse as you move the cursor - or use two fingers on touch screens), then give the selection a name.

You can also adjust the weather conditions (wind) for each bookmark. The program will remember your adjustments. This is very useful when the wind rotated throughout the day.

To learn more about races, please watch [our videos on race management](/blog/tactics-performance-maneuvers-analyze-the-race-leg-by-leg).


CHARTEDSAILS BLOG

Justice on the Water: How ChartedSails Data Resolved a Racing Dispute

Justice on the Water: How ChartedSails Data Resolved a Racing Dispute

Explore further, dig deeper

Compelling Sailing Debriefs

Take your Garmin Watch sailing

One design coaching basics with Fuzz

Tactics, Performance and Maneuvers - Analyze the race leg by leg

Use your GPS to ping the start line

Learn from sailing data: Downwind Technique

Learn from sailing data: good and bad tacks

Five tools to analyze your sailing tracks

8 ways to record GPS tracks of your sailing drills and regattas

Share sailing sessions with the crew

Trim your sailing tracks