A typical ship is going to be out at sea for a long longer than an hour. A drone-net that only lasts for an hour isn't exactly a persistent detection zone. If you want something with range + speed, you're going to need size for the power plant and fuel. Maybe you could hack together something with drones coming back to a mothership to recharge.
Fundamentally underwater hydrodynamics is still in its infancy. How do I know? I just have to look at a shark.