Chart Navigation & Plotting · Tidal Currents — Velocity Interpolation
The Tidal Current Tables give a maximum flood of 2.4 knots. Using the table of velocities, the current about midway in time between slack and maximum flood is approximately:
- A1.7 knots✓ Correct
- B2.4 knots
- C0.5 knots
- D1.2 knots
Explanation
Reversing currents follow roughly a sine curve. The Tidal Current Tables Table 3 factor at about the midpoint between slack and maximum is near 0.7, so 0.7 × 2.4 kt ≈ 1.7 knots — not the simple half (1.2 kt), because the current builds along a sine curve rather than linearly.
Authority: NOAA Tidal Current Tables, Table 3
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