Undefined. Saito had never seen that word in a manual. Not "error." Not "failure." Undefined.
Saito looked at the chart. The Mirai Maru was crossing the Kuril Trench, where the Pacific Plate grinds beneath the Okhotsk Plate. The seabed was a graveyard of basalt and serpentinite—dense, magnetic, heavy. The manual did not have a page for "subduction zone metaphysics." But it had an appendix:
"Local variations in gravitational gradient exceeding 0.0003 m/s² may induce a precession torque on the gyroscopic element. The CMZ 700 will reject up to 0.0005. Beyond that, output is undefined." yokogawa gyro compass cmz 700 user manual
He read further. Chapter 6: A list of things that could confuse the laser ring: rapid acceleration, magnetic storms, nearby large masses of iron… and undersea geological anomalies .
Tanaka came up with coffee. "Captain? The auto-helm is acting strange. It keeps trying to correct two degrees to port." Undefined
"This instrument is designed to find north. It is not designed to understand why north moves."
Saito closed the manual. "GPS can be jammed. A gyrocompass finds north because the Earth turns beneath it. It is a conversation with gravity and rotation. It is… honest." The first three weeks were flawless. The CMZ 700’s digital display glowed a soft amber, a line of latitude and a bearing so steady it seemed painted on the glass. Saito found himself checking it at 2 AM, when the sea was black and the Mirai Maru was just a string of lights in an abyss. The manual’s chapter on promised stability in rough seas. It delivered. Even in the rolling swells south of Hokkaido, the bearing never wavered. Saito looked at the chart
Page 1-2: "The CMZ 700 utilizes a dynamically tuned ring laser gyro. No moving parts. Settling time: 3 hours." No moving parts. That felt wrong to Saito. A ship without a spinning wheel of bronze and copper was like a heart without a beat. But the numbers were seductive. Accuracy: 0.01 degrees secant latitude. Mean time between failure: 50,000 hours.