I came across a previous thread on here which had a very helpful formula to calculate the difference between 2 headings using the MOD function

I work on a vessel and we always have a reference heading of a piece of equipment on the seabead called the 'datum bore heading'.

Now throughout this job we effectively work in a square and the datum bore will always be. FWD, STBD, AFT or PORT in relation to vessel heading

Im trying to wirte a formula where I imput vessel heading and datum bore heading and it tells me FWD, STBD, AFT or PORT

Now FWD and AFT are I can manage. If the difference between two headings is 45 or less then its FWD. if its greater than 135 its AFT

Between 45 or 135 is PORT or STBD depending on which way vessel turns. If vessel turns clockwise on compass then bore heading on PORT and and if anticlockwise its STBD

Anyone know how to write such a thing on excel?

Thanks