Draft Survey • Cargo Weight • Six Drafts • Perpendicular Correction • Hog/Sag • Trim • Density • Deductibles

Draft Survey Calculator: Cargo Weight, Trim & Density Correction

Estimate cargo loaded or discharged from before-and-after vessel displacement. Simple mode gives a fast cargo-weight screen from ship-table displacement, trim correction, density and deductibles. Advanced performs six-draft reduction, corrections to perpendiculars, selectable hull-deflection treatment, first and second trim corrections, density correction, deductibles and survey-quality diagnostics.

Figures represent
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Need much more depth? Click Advanced above.Advanced adds six port/starboard draft readings, draft-mark offsets, corrections to perpendiculars, 6:1:1 / 4:1:1 / custom hull-deflection methods, LCF and Nemoto trim corrections, structured deductibles, density checks and a survey action board.
Fast9 primary inputs
Core answerCargo loaded or discharged
Transparent1.025 t/m³ table basis disclosed

Fast Cargo Weight Screen

Use ship-table displacement extracted for each survey condition. Enter the total signed trim correction from the vessel calculation or approved table. Simple mode applies density and changes in non-cargo deductibles.

Initial survey
tonnes, before density correction.
tonnes, signed. Positive adds to displacement.
t/m³, apparent density used for draught survey.
tonnes. Ballast, bunkers, FW, LO and other non-cargo changes.
Final survey
tonnes, before density correction.
tonnes, signed.
t/m³.
tonnes.
tonnes. Used only to show a difference, not to judge an automatic pass/fail.

Vessel & Calculation Basis

Use the sign conventions shown below consistently with the vessel’s approved hydrostatic information.

metres.
t/m³. Common salt-water basis is 1.025.
Used only for custom-factor mode: AMD + factor × (Mid − AMD).
optional tonnes.

Draft-Mark Positions

Offset sign convention used by this tool: enter a positive offset when the draft mark is forward of its reference station (FP, midships or AP), and a negative offset when it is aft. Trim is positive by the stern. LCF is positive aft of midships and negative forward of midships.
m from FP.
m from midships.
m from AP.

Initial Survey

Six observed drafts
Hydrostatics at the calculated adjusted mean draft
tonnes, extracted/interpolated from approved hydrostatics.
tonnes/cm.
metres. + aft, − forward.
t·m/cm.
t·m/cm.
tonnes. Used only if approved-table method is selected.

Final Survey

Six observed drafts
Hydrostatics at the calculated adjusted mean draft
metres. + aft, − forward.

Non-Cargo Deductibles

Enter tonnes present at each survey. Permanent lightship need not be re-entered in a before-and-after survey because it cancels. A ship constant may be included if it is part of the agreed survey method.

Deductible typeInitial tFinal t

Survey Readiness

Calculation inputs may be stored to improve Ship Universe tools. Benchmark participation is separate. Privacy Policy.
Survey limitation: a draught survey is a measurement-based commercial quantity assessment, not an exact weighing system. Accuracy depends on draft readings, hull deflection, approved hydrostatics, water-density sampling, tank soundings, trim/list corrections and accounting for all weight changes. The vessel’s approved documentation and the agreed survey procedure control the final signed result.
Methodology context: the calculation chain follows established draught-survey practice reflected in UN ECE ECE/ENERGY/19 and P&I guidance: before-and-after displacement, corrections to perpendiculars, hull-deflection treatment, trim correction, density correction and non-cargo deductibles. The 6:1:1 mean-of-means method is not treated as universal; Advanced also includes a fuller-form 4:1:1 option and a vessel-specific factor method. Use the ship’s approved hydrostatic and tank data, sign conventions and any approved trim-correction tables where provided.
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