Ah, then you need to go into the settings of your speed/cruise. I know that on my Perfect pass, I have the ability to adjust the digital readout of the speed that's showing on that unit. it's in the area where I'd adjust where I adjust KDW and NN I believe (the agressiveness and sensitivity of my Perfect pass). I have to imagine that whatever system is in your boat can do the same. You just have to get into the speed calibration menu.
looks like this thread might provide some insight. you're looking for "offset".
https://forum.moomba.com/showthread....lp-for-15-Mojo