Quick question about mission objectives - range that ships sunk count?

[Dread Knot]

Originally Posted by Raven Morpheus

In SH5 I've read that you can sink ships as far out as something like a 200km radius of the objective marker and they count towards the tonnage required to complete the objective.

In SH4 is there such a range from the objective marker at which ships sunk won't count towards the objective?

For example yesterday I completed the first campaign mission where I was ordered to a point just south of Honshu and had to patrol that area. I set an area with 100 nm radius centred on the objective mark using the compass and patrolled that area, but a lot of convoys/ships were outside of that area and I'm wondering if I could have made my life easier by engaging them, because I wasn't finding many ships/convoys in the 100nm radius area I had set.

In SH4, you should try to sink every enemy vessel worthy of a torpedo. Even if you run into one just outside your home base. It all counts toward tonnage sunk, objective marker or no.