imagine boat with crane on it in calm water. the deck on the boat is parallel to the water. If the crane's arm is protruded out and weight is lifted the angle of the deck of the boat will change. then there could be a wave action that will roll the boat an the top of the list created by the lifted weight. I would like to measure and filter that with Arduino and sensor.
the running time of the device will be more then an hour and that's why i was concerned (or should I?) about drift.
the accuracy of 0.5 deg is plenty. sampling as often as needed, but the output 2 to 5Hz.
the sensor I was asking about was
http://playground.arduino.cc/Main/MPU-6050
i hope that clarifies it a bit.