Easiest to just start with some simple intercepts. You don't even need to have the map scale correct for that.
Just capture a screen from the game map, pull it up in MoBo and plot your subs position/vector and the contact position/vector and then hover mouse over contact and press "I" to generate the intercept.
Plot a node on the intercept point and press Spacebar-B while hovered over it to connect a line to your sub and display the bearing.
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