Simple mean, mean-of-means, and UNCTAD true mean at LCF.
Formula
$$ T_{MoM} = \tfrac{T_F + T_A + 6 T_M}{8}, \quad T_{LCF} = T_{mean} + \text{Trim} \cdot \left(\tfrac{LCF}{L_{pp}} - \tfrac{1}{2}\right) $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $T_F, T_A, T_M$ | Forward, aft, midships draft | m | sextant / visual |
| $LCF$ | Long. centre of flotation from AP | m | hydrostatic table |
| $L_{pp}$ | Length between perpendiculars | m | ship particulars |
| $Trim$ | Aft − fwd draft (stern positive) | m | derived |
| $T_{LCF}$ | True mean draft at LCF | m | result |
Sources
- UNCTAD - Draft survey guidelines (1991).
- Derrett & Barrass.