Trim Optimisation

A slight bow-down or bow-up trim shifts the wetted surface and pressure field; the optimum trim at a given speed and loading condition typically saves 1–3 % of propulsion fuel. This tool estimates the saving from the trim-vs-resistance curve slope.

OpsTrim

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

\Delta F = \text{ME}_\text{ref} \cdot p_\text{trim} \cdot f_\text{cov} \cdot \frac{h}{24}

Symbol	Meaning	Unit
$\Delta F$	Fuel saved over the period	t
$\text{ME}_\text{ref}$	Main-engine daily fuel rate at even-keel reference	t / day
$p_\text{trim}$	Resistance reduction at optimum trim	fraction
$f_\text{cov}$	Share of voyage hours where optimum trim is practical	fraction
$h$	Hours at sea	h

Source: NAPA - *Trim Assistant / Loading Computer*; Kongsberg - *K-Trim*; IMO Resolution MEPC.282(70) - SEEMP guidance on trim optimisation

In short

Fuel and CO₂ avoided by running a ship at its CFD-derived optimum trim rather than even keel.

Learn the theory Decarbonization Technologies for Ships