Generally if you have deduced that your MHU requires an offset (due to mount - NOT due to wind shear), then you must adjust by half the difference from tack to tack.
Example, Port tack reads AWA 25, Stbd reads 23 AWA - the error is 2 deg, therefore you need to adjust your MHU offset by 1.
Most instrument systems will require you to adjust by +1 in this example which will increase your Stbd AWA by 1 and reduce your Pt AWA by 1.
You need to be sure that the error is real, not wind shear, and not a case of actually sailing a different angle tack to tack (due to waves, setup/trim etc).
Generally if you have deduced that your MHU requires an offset (due to mount - NOT due to wind shear), then you must adjust by half the difference from tack to tack.
Example, Port tack reads AWA 25, Stbd reads 23 AWA - the error is 2 deg, therefore you need to adjust your MHU offset by 1.
Most instrument systems will require you to adjust by +1 in this example which will increase your Stbd AWA by 1 and reduce your Pt AWA by 1.
You need to be sure that the error is real, not wind shear, and not a case of actually sailing a different angle tack to tack (due to waves, setup/trim etc).