Okay you military types...question. Do warships not have radar/sonar/someshit that warns of incoming missles, torpedoes etc.? I mean, even in the black and white war movies they knew torpedoes were coming and took evasive action. John Wayne would never have allowed this to happen.
The bigger ships have sonar, which will only alert them to the presence of a submarine. The only known detection device available (from the surface perspective) against a torpedo attack is the good ol' eyeball. Rapidly approaching bubbles are generally the first telltale sign that a torpedo is inbound. Destroyers, frigates and such have hydrophones that are used to listen for subsurface threats but are extremely limited in accuracy. You have to have a calm ocean and a damn alert & highly trained operator listening for the high pitched "whirr" of the torpedo. The probability of detection is 60% at best, and that's with modern equipment seen most commonly with major navies. Patrol boats, such as this one, are pretty much fucked.
Incoming missiles are more easily detected. Practically every ship has some sort of air search radar.
John Wayne was full of shit.