nav - might be stupid question
 

I am trying to calibrate my nav unit and have done everything that i have been told to do, but when i turn right or left it does the opposite to what i am doing. I have looked in the boot and the nav unit mk4 is upside down in the boot. Will this be the cause of it or is the compass somewere else? Also if i do need to flip the nav unit over is it easy and how do i do it. thanks

Yes, that is probably your problem. Flip the MKIV. Insert coat-hanger sized pieces of wire into each of the four hols around the face. That will free the spring clips, and the MKIV will slide out of the bracket.

Definitely, an upside down nav will have left swapped with right due to the gyro compass being upside down.

Turn it the right way up and then recalibrate and all will be well.