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Wetted Surface - Mumford Formula

Wetted-surface estimate for displacement hulls from LWL, T and displacement. Used for quick resistance estimates when offsets are unavailable.

ResistanceWetted surface
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Formula, assumptions, and limits

S=1.7LT+TS = 1.7 \cdot L \cdot T + \frac{\nabla}{T}
SymbolMeaningUnit
LLWaterline lengthm
TTDraftm
\nablaDisplacement volume
SSWetted surface

Source: Mumford quoted in SNAME PNA Vol II Ch.5

In short

Wetted-surface estimate for displacement hulls from LWL, T and displacement.

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