Tons per Centimeter Immersion (TPC)
Compute the tons per centimeter of immersion (TPC), TPC = Awp·ρ/100, from the waterplane area (Awp, in m²) and the water density (ρ ≈ 1.025 t/m³ at sea). It indicates how many tons of cargo must be loaded (or removed) for the ship to sink (or rise) by 1 cm. It is essential in the loading plan and draft control. Enter the waterplane area and the water density.
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Tons per centimeter immersion (TPC)
How much cargo must come aboard for the ship to sink one more centimeter? That figure is the TPC (tons per centimeter immersion) = A_w·ρ/100, computed from the area of the waterplane (the 'slice' of the hull at the waterline) and the density of the water. The logic comes from Archimedes: sinking 1 cm displaces an extra volume equal to the waterplane area × 1 cm, and the weight of that much water equals the cargo that fits. TPC is a daily tool of the chief mate in the loading plan: predicting the final draft, distributing weight and staying below the Plimsoll line. Since fresh water is less dense (1.000) than salt water (1.025), the same ship sinks deeper in a river. Enter the waterplane area and the water density.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.