Hi Ui-boat scales correctly no matter if 4:3 or 16:9 so you should have no problem with the RAOBF in its use
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The RAOBF is dependent on the Graticules of the scopes to be correct in order to get proper calculations.
Ui-Boat V3 is calibrated to correct Field of View and Degree spacing at all resolutions and screen aspect ratios thanks to Makman94.