First steps 

Main Navigation Widgets

At the top of the page, you’ll find the main navigation widgets:

• My Boats – manage your boat profiles
  
  

• Upload New Data – import session logs (CSV, NMEA, etc.)
  
  

• Browse Old Data – view and analyze previous sessions
  
  

• Rig Analyzer – (coming soon) check mast and rigging load data
  
  

• Sail Shape Analyzer – (coming in the second major update) advanced sail shape visual analysis from onboard photos and video
  
  

My Boats

Upload Data 

Browsing Past Sessions

• Go to “Browse Old Data” to view your full session history.
  
  

• Each session includes a summary (date, boat, wind conditions, duration) and a preview of key metrics.
  
  

Session Comparison

• You can select up to 3 sessions at a time to compare them side by side.
  
  

• This helps you identify performance improvements, test gear changes, or compare different conditions.
  Video Playback Note

• If you open sessions that were recorded on different days, the video player will be disabled.
  
  (Synchronized video playback is only available for sessions from the same day in Beta version)

Rig analyzer 

Session overview

Manouvers Analysis

Our goal is to maximize both the total distance covered and VMG distance during maneuvers while minimizing the overall maneuver duration and associated distance losses.

Visualization Methodology

Maneuvers are visualized using a 20-second analysis window, allowing clear insights into each boat's performance dynamics. Each maneuver graph illustrates the average performance for all maneuvers of the same type executed by the boat during the session.

PITCH

• Pitch indicates the fore–aft trim of the boat and helps understand how the boat is moving through the water.
  
  

• On most modern boats in light wind, it’s faster to sail with a slight forward pitch (bow down), which lifts the wide stern out of the water and reduces drag.
  
  

• In strong wind, most fast modern boats perform better with a neutral (flat) pitch, keeping the wide stern in the water to allow planing.
  
  

• On foiling boats, pitch is used to estimate the angle of attack of the foils in the water — a key factor for lift and stability.
  
  

What to aim for:

• Ideally, the peak turning rate should be in the middle of the maneuver, with a smooth increase before and smooth decrease after.
  
  

• Higher turning rates are not always better. Efficient turns are about balance — turning just fast enough to minimize distance lost, but without excessive rudder use or speed drop.
  
  

• Compare your turning rate to heel and pitch: a well-synchronized maneuver shows harmony between rotation, heel direction, and fore–aft trim.

True wind angle

Q: What is True Wind Angle (TWA) and how should I interpret it?

A: TWA — or True Wind Angle — is the angle between the boat’s heading and the true (ground-referenced) wind direction, measured in degrees. It’s one of the most important metrics for understanding sail trim, maneuver timing, and tactical positioning.

How to read it:

• TWA is usually shown as a positive angle on either side of the wind — e.g. 45° upwind or 135° downwind.
  
  

  • 0° TWA = head-to-wind
    
    

  • 90° TWA = beam reach
    
    

  • 180° TWA = dead downwind
    
    

• During a tack or gybe, the TWA swings quickly from one side of the wind to the other, often passing through 0° or 180°, respectively.
  
  

• TWA graphs often help visualize the sharpness and symmetry of the maneuver — e.g. how steeply you cross through the wind and how fast you establish stable sailing after.
  
  

What to aim for:

• When sailing upwind, you want to stay as close-hauled as possible (typically ~40–45° TWA) without losing speed. Monitoring TWA helps you find that sweet spot.
  
  

• When sailing downwind, maximizing VMG often means not going directly downwind, but sailing at an optimal broad reach (e.g. 140–150°) and gybing as needed.
  
  

• During maneuvers, TWA can show whether the boat reacts quickly to the rudder and trim. A smooth and symmetrical TWA curve usually reflects a clean and efficient tack or gybe.
  
  

Distance loss (pure speed and VMG)

What to aim for:

• Minimize total loss per maneuver:
  
  Well-executed tacks and gybes often show under 8–10 meters of distance lost on average (depending on boat type and conditions).
  
  

• Compare Speed Loss vs VMG Loss:
  
  If VMG loss is much greater than pure speed loss, it likely means you lost angle, not just speed — perhaps over-rotated, or didn’t settle on the right course fast enough.
  
  

• Look for consistency across maneuvers:
  
  Large variation between similar maneuvers may indicate unstable technique, especially under pressure or in gusts.
  
  

Training insights:

• Track progress over time — repeat drills aiming to gradually reduce average distance loss.
  
  

• Use these graphs to debrief team communication and timing, especially around turns.
  
  

• Combine with Heel / Pitch / Turning Rate to see what’s physically causing the loss — and where you can gain it back.
  
  

Accumulated distance passed (Pure and VMG)

What to aim for:

• Steady and steep curves indicate consistent speed and VMG — you’re converting time into meters efficiently.
  
  

• Compare the two curves:
  
  

  • If pure distance is growing but VMG distance is not, you’re moving — but not toward the mark. That means you’re sailing at a poor angle.
    
    

  • If both graphs are flat, you’ve either stalled or maneuvered inefficiently.
    
    

• After a maneuver, both lines should recover quickly and return to their previous slope — this shows good re-acceleration and course setting.
  
  

Training insights:

• Use these graphs to evaluate macro-efficiency over time, not just during maneuvers.
  
  

  • Are your long tacks equally productive?
    
    

  • Are you consistently gaining distance toward the mark?
    
    

• Identify sections with the best slope — they often represent ideal trim, angle, and balance. Use them as a reference.
  
  

• Watch for performance drop zones: where both graphs flatten or diverge — these are moments to review in video or debrief.
  
  

Capabilities of the graph

Graph Controls

• Metric Selection Panel:
  
  Choose which performance metrics to display:
  
  

  • SOG, VMG
    
    

  • HEEL, PITCH
    
    

  • Turning Rate, TWA
    
    

  • Distance Loss, etc.
    
    

• Smoothing / Raw Toggle (if implemented):
  
  Switch between smoothed and raw data — helpful for identifying trends without noise, or inspecting real-time reaction.
  
  

• Split Graph View:
  
  Option to view multiple synchronized graphs in vertical alignment (e.g., SOG + HEEL + Turning Rate on one screen).
  
  

Exporting and Sharing

• Export to image or PDF:
  
  Save any graph as a .png or .pdf for reporting, coaching, or presentation.
  
  

• Copy to clipboard:
  
  Quickly copy a graph for use in slides, documents, or chats.
  
  

• Export with synced video :
  
  Align graphs with on-board footage for full debriefs.
  
  

Manouvres table

VMG (Velocity Made Good) Metrics

• VMG_on_entry
  
  → VMG before the maneuver starts
  
  Useful as a baseline reference for performance loss.
  
  

• VMG_on_exit
  
  → VMG after the maneuver finishes
  
  Shows how quickly the boat resumes effective progress.
  
  

• VMG_avg
  
  → Average VMG over the entire maneuver
  
  Key indicator of overall efficiency.
  
  

• VMG_min
  
  → Lowest VMG during the maneuver
  
  Indicates the worst point of performance drop.

Straight Lines Analysis

The Straight Line Analysis section is designed to help you improve your boat’s performance on steady courses — both Upwind and Downwind. It breaks down your sailing into clean, stable segments and allows you to optimize speed, angles, and balance.

Structure of the Section

The section is divided into two main parts:

• Upwind
  
  

• Downwind
  
  

Each part includes three subsections:

1. Charts – visual plots of key metrics like SOG, VMG, TWA, HEEL, PITCH, etc.
   
   

2. Tables – numerical summaries and averages for each segment
   
   

3. Correlations – statistical links between variables (e.g. heel vs. speed)
   
   

What is the goal?

The primary objective is to:

• Increase average and maximum speeds
  
  

• Improve angles of attack to the wind
  
  

• Reduce instability by lowering variations in boat behavior
  
  

This is usually achieved by:

• Finding the optimal True Wind Angle (TWA)
  
  

• Optimizing Heel and Pitch for given conditions
  
  

• Reducing standard deviation (STD) of each metric
  
  

What is Standard Deviation (STD)?

Standard Deviation (STD) measures how much a value fluctuates from its average over time. In sailing:

• Low STD = stable, consistent sailing
  
  

• High STD = unstable trim, inconsistent helm, or unsteady wind response
  
  

For example:

If your TWA has a low STD, it means you’re holding a clean and steady course.

If your HEEL STD is high, the boat may be rocking or reacting to gusts too aggressively.

Violin Plots 

How to read our violin plots

• The left half of the plot shows data for port tack
  
  

• The right half shows data for starboard tack
  
  

• Each color represents a different boat (e.g. ITA-1, ITA-2)
  
  

The X-axis represents time, but in violin plots like these, it’s used to show distribution shape.

The Y-axis represents the value of the selected metric (e.g. HEEL in degrees)

What are the median and quartiles?

• Median (middle dashed line):
  
  The middle value — 50% of all values are above it, and 50% are below.
  
  → In sailing: the most typical value of the parameter
  
  

• Quartiles (top and bottom dashed lines):
  
  

  • Q1 (25%) and Q3 (75%)
    
    → Together with the median, they show the central 50% of the data
    
    → If the quartiles are close to the median, it means your sailing was consistent and stable
    
    → Wide spread between quartiles = high variability, which you may want to improve
    
    

Goal: Narrow, centered violin shapes with stable median lines mean consistent performance.

Example (from the HEEL graph above):

• ITA-1 (blue) has slightly more heel to starboard than port, and more consistency
  
  

• ITA-2 (orange) shows greater variation in heel to both sides, especially on port tack
  
  

• Median and quartile lines help highlight whether your trim and balance are symmetrical across tacks

Standard Deviation Plot

How to interpret this plot

• Lower STD = more consistent heel → a more balanced and stable boat
  
  

• Higher STD = more instability → e.g. rocking, crew imbalance, gust reactions
  
  

From the graph:

• ITA-1 (blue) has slightly better stability, especially on starboard tack (STD ≈ 2.27°)
  
  

• ITA-2 (orange) shows more variability on both tacks, especially port (STD ≈ 3.33°)
  
  

• Both boats are more stable on starboard than port — this might suggest asymmetry in crew movement, trim, or steering
  
  

What should I aim for?

• Narrow violin shape → consistent control
  
  

• Low median STD → better balance and sail setup
  
  

• Compare port vs starboard to detect tuning or handling asymmetries
  
  

• Use these plots to track improvement over time as you refine your settings

Speed (sog_kts) and VMG

VMG – Velocity Made Good

• VMG represents speed toward or away from the wind, depending on your sailing direction:
  
  

  • Upwind VMG = forward progress against the wind
    
    

  • Downwind VMG = speed moving away from the wind
    
    

• VMG is the true performance metric in racing, as it reflects how efficiently you’re closing in on the mark.
  
  

In violin plots, a high and narrow VMG shape means strong and stable performance.

A flat or double-hump shape may suggest inconsistent trim, sail setup, or angle holding.

How to use these plots in practice

• Compare port and starboard for symmetry — is your setup equally effective on both sides?
  
  

• Look for high median values and narrow plots = ideal: fast and stable.
  
  

• Use these insights to test trim changes, mast rake, or crew positioning effects.

Speed and VMG STD

From the example:

• Median SOG_std is around:

  • 0.25 knots on port (orange)

  • 0.26 knots on starboard (orange)

  • 0.22–0.24 knots for the blue session

• All values are relatively low, which is a good sign of stability

What does this tell you?

• Both port and starboard tacks are equally stable — no major asymmetry in speed behavior

• Blue (ITA-2) has slightly less variation, especially on starboard

• If this value were above 0.5–0.6 knots, it might suggest:

  • Irregular trimming

  • Poor helm balance

  • Response to gusts or waves
    
    

What to aim for

• Low and narrow violin shape = consistent, high-quality sailing

• Use this plot to benchmark tuning sessions or compare different crew configurations

• Track whether changes to sail shape or weight placement improve stability over time

Course Over Ground/True Wind Angle

HEEL-PITCH-STD

What does the HEEL_std plot show?

The HEEL_std plot shows how much the heel angle fluctuates during straight-line segments. A lower standard deviation means more consistent and stable boat balance. Higher values indicate unstable heel caused by gusts, poor trim, or active crew movement. Compare port and starboard sides to check for asymmetry. Narrow plots with low median values are ideal. Use this metric to evaluate control and the effectiveness of tuning or crew trim.

Straight Line Tables

Correlation Plots

Video Player and Interactive Map

Map Player

Key Features

• Playback of GPS trajectories for all boats

• Full synchronization with speed, VMG, heel, pitch, and other metrics

• Visual overview of your tactical movements and maneuvers

• Every white line on the timeline highlights  manouvre of the boat - tack, jybe, or mark rounding.
  
  

Map Interaction

• Double-click on the map to add a custom marker (e.g., layline, wind shift, tactical note)

• Drag markers to reposition

• Double-click on a marker to delete it
  
  

Automatic Start Line Detection

If your uploaded VKX file contains:

• Start line position

• Time to start

…then this data will be automatically parsed and added to the map player.

Start Line Tools

To visualize:

• Distance to the start line

• Time to start

…simply enable the corresponding metrics in the graph view. This gives you real-time overlays during playback — ideal for evaluating prestart tactics.

Would you like a section explaining how to export or share Map Player replays as part of a session review?

Video Player

Synchronization Check

Make sure the videos are correctly aligned with the session data.

Video and data must be synchronized by timestamp to ensure accurate playback.

Adjusting Offsets

If the video is not correctly synced, you can:

• Apply a custom offset to each video individually
  
  

• Or apply the same offset to all videos at once
  
  

This helps align video playback with maneuvers, speed changes, and other recorded metrics.

Export to Socials

Orientation Check

• Press Start to generate the video
  
  

• If the result appears horizontal, use the Force Rotation option
  
  

• Some smartphone videos contain rotation metadata that may confuse the default orientation
  
  

Render and Share

• Press Start again to render your video
  
  

• In a few seconds, you’ll get a clean, synced, vertical video — ready for Instagram, TikTok, or Stories
  
  

Give us a mention

Don’t forget to tag @ktool.hu and @kistanovarkadiy when you post your results!