HELP! RA/DWX SOSUS Use?

[artao]

In the mission I'm building, I put down a SOSUS array. In DWX the SOSUS sensors are under Civilian > Surveillance .. the specific sensor appears to be "FFQ-10 Sosus Array". In the mission editor I turned on sensor range to see how far apart to put them, and how far away they can detect. The circle thus created is about 30nm radius.

To test the SOSUS array, I put in a global event goal with doctrine "Detect Side, player, by side 2" (all sosus sensors are side 2 to make it easy to hide them all to reduce clutter. side 2 is allied with side 1. side 0 is the player) and to then send a report "SOSUS Detection" so I could see exactly when the player can be detected. I set the goal to be retriggerable every 5 minutes, and to have to hold detection for 1 minute to activate.

Here's the problem: I started the player sub a good 80nm away from the SOSUS sensors, and when I got into the mission set the sub (Sturgeon Class) to flank speed (25knts) at 1200 feet deep.
The SOSUS sensors started picking me up around 60 nm!!!
So I started reducing speed to see how slow one would need to go to NOT be detected.
The short of it is this: the SOSUS sensors STILL picked up the sub at a speed of 1 knot, above the layer, from a good 50+ nm away!!
Am I using these wrong, or are they simply functioning improperly?

EDIT: perhaps I should add that this is the first DW mission I've created. I fiddled with mission creation in SC as well, but not a lot.