There is a set up routine, if i remember correctly, take the boat out in an open area, ho starboard, turn hard starboard and press set, the response will be to turn hard port, also press set key, then will say center, press set key, unit will then go thru a self check turning side to side, then unit will say ,make a slow turn in a circle which should take a minute which calibrates the compass, I have the manual on the unit and will check the setup routine-if you need anything specific, drop me a PM. I had sent my unit back to sitex since i had old software on the unit, they upgraded the software for free. when you turn on the unit, the version of software shows up, I had to re set up my sp70 and now working perfectly (have the unit integrated with my furuno gps) Good luck
