S-Class Torpedo Solution From A Novel I Am Reading

[james_nix]

I'm reading a book call Crash Dive by Craig DiLouieed. It's ok so far, just getting into it. It starts out in a S-Boat in October '42 in Australia.

The author describes a way to fire torpedoes thusly.

Speed of ship + 3 = lead angle. So looking at the attached image from the book, a destroyer going 26 knots would have a 29 degree lead angle.

Shoot at 331 and it will hit at 0 degrees. Oh, 1,500 yards or less.

From the book:

"Rusty said, “Here’s how we do it out here in the real world on a broken-down S-boat. We set up a zero gyro angle shot; we have to shoot our fish straight ahead. We estimate the target’s speed, add three to come up with a lead angle, and shoot at that point from between a thousand and 1,500 yards. Sometimes with visual contact, but often going only by sound bearings.”

Is this how they did it without a stadimeter? The picture shows how the fish went all screwy and messed up the attack.