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Free Draft Survey Calculator

Professional online calculator for marine surveyors and cargo officers. Quarter Mean, trim corrections, density correction, and cargo weight — step-by-step with full formulas shown.

Input Data

Draft Readings (metres)
Water Density
Ship Data (from Hydrostatic Tables)
Additional Weights (tonnes)

Calculation Results

Enter values and click Calculate to see step-by-step results.

Related Resources

Did You Know?

On a Capesize bulk carrier, a draft reading error of just 1 centimetre represents approximately 60-100 tonnes of cargo. That is why the Quarter Mean formula is essential -- it weights the midship reading six times more than forward and aft, suppressing the effect of hull bending (hogging or sagging).

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Manual readings are subject to parallax errors, wave interference, and human fatigue. GOTEC's AI-based draft measurement system reads all six draft marks simultaneously with machine vision, reducing survey time by 30% and eliminating reading errors. Explore our product range for ports, terminals, and independent surveyors.

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