Go into >Openplotter>Settings and then hit refresh.
In the list of openplotter Apps, go down to I2C Sensors and select then install.
Now go to >Preferences>Rasp Pi Config and go to the interfaces tab, enable I2C.
Powerdown the Pi and install the sensor(s)
I2C uses several pins - pins1 (3.3V), 3(SDA), 5(SCL), 9(GND). Connect them up accordingly based on your devices.
Power the Pi back up
Got to >Openplotter>I2C and add all sensors providing a name for each that makes sense and fits with the Signal K specification, see http://signalk.org/specification/1.0.4/doc/signalk.pdf, see the picture below:
On the connection Tab, add connection to Signal K for each of the sensors:
The Pypilot entry will not show up until you have done the Pypilot configs