Use AFTrack for Sailing


There are some useful settings for sailors

will be found in GPS settings,
wind speed units in Display settings
GPS Mode
GPS data can come from different devices. For online and bluetooth an extra definition is needed.
Online GPS comes over TCP, UDP or as a Signal K websocket. For websocket it is possible to define an address like or  an ip

Online settings

When the incoming GPS signals are not satisfying, it is possible to work in a mixed mode. The position messages from an external device are ignored than and for position the internal GPS is used.
GPS Mixed Mode
Collect NMEA data from external services (Bluetooth, Wifi, USB) but use the internal gps for prosition
Wind IndicatorWind indicator on position
Display settings, shows a wind arrow with feathers
10 Minutes Distance
Display settings, show an arrow from position to the probable position in 10 minutes,
if AIS entries on display they also have an arrow.
Wind Info
Wind Info on Map
Display settings, shows a wind information on map

With a tap on the wind info a pop up shows the wind settings

Wind Settings
When not internal is selected, the info shows the weather values of the nearest station to the map center. This is updated every 5 minuetes.
Other options show different results.

For use of an internal wind feature, please select this and press the arrow to define a wind direction and speed by hand.
Wind definition by hand
When there is no input for an external wind instrument this values are used.

Wind Routing
Display settings, enable the use of wind informations for the GoTo or routing mode
Layline Way point
Layline on a way point
Display settings, shows the laylines of the way point in GoTo mode
Boat Display settings, defines best angle to wind and max speed
This values are used for wind routing calculation when no polar values available.

Boat settings When polar values from a file should be used check the box. The files should be stored in AFTrack folder /data/aftrack/polar like the default.csv CSV files are converted to a xml file and also placed in polar folder.
AIS Dock
Display settings, replaces the profile dock view with an AIS list

AIS Dock
AIS small icons Show the AIS symbols in smaller layout and scale it when possible

AIS icons
AIS track
Show a path for a ship or for all ships

AIS track
AIS group
Show a group of ships in a seperate color. Please define a file with name 'aisgroup.txt' and place this into the AFTrack folder 'conf'.
The file contains a MMSI on each line.

AIS group
Anchor Alarm Select the overlay button and set the alarm

For some clearing have a look to Wikipedia for Tacking or Jibe.

Sea Charts

Main used chart format in AFTrack is the BSB format. You will find some sources here.

You could also use the NV-digital, this is encrypted BSB3 format.

The new NV-digital tiled format is also available, please do a map scan, when installed.

Get maritime chart collections for USA, Cananda, UK and NZ from here

Planning a Trip

It is recommended to switch off the GPS first to get a clear planning of a trip. Work with fixed values for wind and speed.
Press a point on the map for a longer time and select the ruler for a route design.

Routing with wind
The distance is not only calculated from the point to point distance. It also contains the laylines from point to point when next point is not reachable in a direct way.This is an idealistic way of view to the route. The boat has to do some more tacks then the display shows.
Please keep in mind, we are not calculating current, drift, wave or cost of maneuvers.

On the Water

Use the wind instrument for an orientation.

Wind instrument Wind intrument with polar
with boat parameter
with polar values

The outer ring shows the boat direction and has the true wind in cyan and a blue area for the one hour wind average with cyan center and the direction of change on one end.And an arrow to the selected way point.
The inner circle shows the relative wind situation with the best tack angles (from settings or from the polar values). Also a four minutes average of the true wind relative to the boat which helps to assess teh situation.

Please keep in mind, the four minutes wind average can be better than the best tack angle because there are influences by waves and current. Before you edit the boat parameter for that please have a look on the opposite site if there is the same deviation.

On a Trip you tap a way point and select the arrow button. This starts the GoTo mode.
Like this

GoTo mode with wind
The route at GoTo mode start is displayed in magenta.
All other values are recalculated continuously. Notice the 10 minutes position and the laylines of the way point.

Please keep in mind this is an idealistic view. Newer go direct to the laylines accept the last half mile.
It is better to stay in the green area not to get in trouble when wind direction changes.

A better way using laylines

Standard situations during sailing

Wind from direction of way point. Both legs are equal and there is no favorite side.

course to way point sample 1

The Wind again comes from way point direction but way point isn't in direct position. The course line is shown like this because ship is going this direction.
But it's recommended to tack to come into the favorite area (dotted lines) in the middle of tack angle to protect you for wind shifting.

Another problem is the current. AFTrack trys to calculate it from course over ground and course through the water.
In this case an extra line is shown (green line, this means not a star board line, it' only an opposite line).
Again it's recommended to tack as you see on the side. Layline 2 is shorter and will bring you to target ealier.
The green line ist shown when the gap of both distances are greater than 100 m - tack will cost you a little bit.

Planning a Regatta

AFTrack  has a feature which could be useful for regatta planning: Insert a way point selection.
You have to activate this feature before using.
And you need a definition file with the name wptcollection.txt. A sample is found in AFTrack folder conf. Build something like this:

# first line wpt group name, icon
# all other are wpt: name, icon

And copy new icons to the AFTrack icon folder.

When it is activated you have a new entry when you do a long press on the map

way point collection

After pressing the third button a new way point group is added and you have the collection icon on the map.

Regatta collection

When you tap on this icon all related icons are shown around the collection point.

Regatta all tons

Move the points to its favorite places and send the waypoint group to the participants by export.
Set the  property of the group from 'As Collection' to 'Visible' to see all  points on the map.

Regatta collection

Get a wireless Anemometer

To handle external devices with special specification AFTrack uses plugins, see here
One of these is for the SailTimer Wind Instrument™, an autonomous and cableless mast head unit using Bluetooth Low Energy for transfer

SailTimer Wind Instrument
Get a discount on the SailTimer Wind Instrument™