Mechanism of tilt–flow-speed-squared correspondence

Determine why mooring-line tilt corresponds to water-flow speed squared only for small tilt angles, despite the drag-force balance predicting a broader relationship and despite the absence of direct vertical-shear measurements.

Background

The paper tests mooring-line tilt as a proxy for water-flow speed squared. The relationship is observed to hold approximately when the tilt magnitude is below 0.13 degrees but breaks down at larger tilts. The discussion attributes the discrepancy partly to the J-shaped deformation of a single-top-buoy mooring and to unmeasured vertical flow variations, but does not resolve why the correspondence is restricted to small tilt.

References

It is therefore not surprising that tilt is observed only partially corresponding with flow-speed squared, although it remains to be investigated why such correspondence is found for small tilt only and even though direct measurements of vertical shear are missing.

— Short spatial mooring-tilt variations from deep Mediterranean observations  (2608.21046 - Haren, 21 Aug 2026) in Section 4, page 12