I want something to give me a numeric heading when sailing - so I can watch how speed varies as heading changes at a given mainsail setting. But all the Compass apps I have tried are sensitive to tilting of the phone - as opposed to just rotation. This becomes problematic in a boat as small as the one I sail as it gets thrown around by chop. i.e. the bow goes up-and-down, tilting the compass on a fore-aft axis. Is the sensivity to tilting built in to the Compass sensor API, or should I keep looking for one that only responds to rotation?