[Umfuld]

Not sure what if any mods you're using. So I'll just tell you what I do. It may be the same as the other post, don't know.

By 'convoy' you must mean when you get a radio report and an icon appears on the Nav Map.
Take the ruler and draw a straight line though the icon (as in, through the rear of the boat through the front and straight ahead). As far as you need to go.
Now just head to that line, ahead of the convoy at top speed.

Some quick, no calculator needed math and you should be able to tell a good spot to aim on the convoys course that you will reach first. They move slow, so it's easy.

And that's it.

What?