I have the app as well. Where did you set it in the boat when you were checking it against auto wake?
Did you just compare the app against autowake and then adjust to make the app "0" and then zero out autowake? Or did you do it how SC suggests?
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At first I did what SC recommends while my phone was on the floor just in front of the drain cover and as it read 0 & 0, I then reset the pitch and roll to 0.
But... when I had the ballast full and people in the boat I double checked the actual against my phone and it was slightly different... so I then adjusted the actual to match my phone. It has been bang on since.