Draft Survey Calculator: Bulk Cargo Weight for Settlement
Calculate bulk cargo weight for invoice settlement using draft survey methodology. Model vessel displacement, ballast, and constant adjustments.
Overview & methodology
Numerical Example: Cargo Quantity Determination
These are the calculator's default readings. Net displacement is the hydrostatic displacement after trim and density corrections, minus ballast, fuel, fresh water and the ship's constant. The 0.33% gap sits within the customary 0.5% survey tolerance.
Method note: calculations run in your browser using the formulas and published rule books cited on this page. Results are free estimates for planning, with no login required, and should be confirmed with your bank, broker or the official source before you commit.
Frequently asked questions
How is cargo quantity calculated from a draft survey?
Take the six drafts, compute the mean of means, apply trim (first and second) and density corrections to displacement, then subtract deductibles (ballast, fresh water, fuel, stores, constants). Cargo = final displacement on completion − final displacement on arrival.
What tolerance applies between the draft survey and the B/L figure?
Commercially, a draft survey is accepted to about ±0.5% against the bill of lading quantity. Larger differences normally trigger a re-survey, a letter of protest, or a shore-scale reconciliation before the master signs.