[MKalafatas]

It's a dark, moonless night. Cruising in the S-boat northwest of Luzon, I dive for a sonar check. (The S-boat has no sonar on the surface). Get a faint reading at compass heading of 100 degrees and --- expecting a convoy from the east, head due south on the surface to engage.

Perfect interception. Except....

I can't see what the hell I'm shooting at. The bow-on approach angle is so acute and the night is so dark, that I can't identify targets. Ergo, I have no range data. Ultimately, I "guess" the target is a large composite freighter and fire four fish with a small spread. All missed.

Some depth charging for my troubles.

What have I done wrong?

Thanks much!