Log your sessions with ease. Share quickly to the SailViewer App
The Sail Logger app is a simple application used for logging sailing sessions, primarily to view them in the SailViewer App. Sail Logger can record the GPS position and the heel/pitch of the boat.
To log only the GPS track, the phone can be placed anywhere on board. The less water that splashes over it, the better the GPS signal reception will be. To log heel/pitch, the phone should be securely fixed. You can adjust the phone’s orientation within the boat using the ‘Rotate’ button.
The phone can be securely fastened using Velcro, zip ties, adhesive tape, or a bike phone holder. It is recommended, especially for boats that encounter heavy waves, to position the phone closer to the stern. This placement ensures that heel/pitch readings are not affected by the strong impacts at the bow
Non-Logging Screen
LOG – starts logging, the screen will change to the logging screen
ROTATE – changes the orientation of the phone for logging the heel and pitch. The boat drawing on the screen shows how the phone should lie in the boat.
ZERO – zeroes heel/pitch. Press when you are sure the boat is leveled. It will countdown for 3 seconds before zeroing to eliminate the movement from the finger pressing the button. Once zeroed, the offset will be saved for the next time the app is started.
SHARE – gives the list of the logs and events. Press on any to open the menu for sharing it. To export pinged events, you can also click on the QR code button. Generated QR codes are easily imported into the SailViewer App via Menu/Events/Read QR.
Logging Screen
UNLOCK – unlocks the button to stop logging. Used to prevent accidental stopping of the logger.
STOP – stops logging data
MARK NOW – inserts the event at the current location and time. The timing and location of the event added is recorded at the time and place when the MARK NOW button is pressed.
It is possible to mark the ends of the start line, start time, and custom text events. When marking the start timing, you can choose the minutes before the start. The timing is always at the point the MARK NOW button was pressed. For custom text, first input the text and then click on “Text Event” button
Settings Screen
BOAT – select the boat number and color.
TEAM – input the name of the team
Log Freq – frequency of heel/pitch logging. GPS data is always logged 1/S. This option increases the amount of heel/pitch points collected. At the same time, it increases the amount of data and can slow down the SailViewer app a bit. So in the case of a keelboat, it can probably be left at 1/S. For faster, more agile dinghies/boards, you can try with higher frequencies.
Extra Pitch/Heel offset – adds a fixed number to heel/pitch. Useful if you know the angle of the place on board where you fix the phone.
Reset Offsets – resets zeroed values of Heel/Pitch to phone original ones.
Events Per QR – how many events are shared in a single QR code. If there are problems reading complex QR with many events, reduce this number.
You can also select which data should be recorded. More fields end up with larger files.
Heel/Pitch Data
Movements of the boat can affect the accuracy of heel and pitch angle measurements obtained from accelerometers.
Accelerometers are sensitive to all acceleration forces acting on them, including those resulting from changes in boat speed, waves, crew, or equipment movement ( rudder/boom…). These forces can generate noise in the accelerometer output signal, which can make it difficult to distinguish the acceleration due to heel angle from other acceleration components.
To mitigate the effects of noise and improve the accuracy of heel angle measurements, advanced signal processing techniques can be used. For example, data filtering, signal averaging, and sensor fusion techniques can be employed to separate the acceleration due to heel angle from other sources of noise. However, this will never be able to completely remove all the noise. So take your numbers with a bit of care. In longer terms heel/pitch averages are pretty accurate. Quick, very short-term movements don’t need to be. Different hardware does not have the same amount of noise and smoothening techniques, so comparing the travel numbers from different devices is not recommended. Also, it can easily happen that the dinghy that steers more violently has more heel travel due to the sudden movement of its stern.