Pivot Point Location - Ship Handling
Pivot point location along the ship when making headway / stern way - the instantaneous point of zero transverse velocity that governs tug-handling.
Pivot point from stern
45m
Interpretation
~¼ L abaft the bow - the usual rule-of-thumb
Formula, assumptions, and limits
$$x_{pivot} \approx 0.25 L_{PP} \ \text{(ahead)}; \ 0.75 L_{PP} \ \text{(astern)}$$
Pivot point shifts as ship accelerates. Stern tug has greatest leverage when ship has headway (pivot near bow); bow tug more effective on sternway. Rotational moment arm = distance from pivot.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $L_{PP}$ | Length between perpendiculars | m | ship particulars |
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