A better voyage starts with better questions.
Explore how a vessel’s speed can affect time, fuel and tank-to-wake CO₂ in a simplified voyage model.
Planning simulation — not for navigation. This calculator does not find routes or use current weather, waves, currents or vessel performance curves.
Your assumptions
| Scenario | Time | Fuel | CO₂ |
|---|---|---|---|
| 18.0 knReference | 6.9 d | 277.8 t | 865.0 t |
| 16.2 kn10% slower | 7.7 d | 225.0 t | 700.6 t |
| 14.4 kn20% slower | 8.7 d | 177.8 t | 553.6 t |
These are model outputs, not predicted savings. Slower travel also takes longer; engine limits, auxiliary loads, schedule costs and weather can change the result.
Model and assumptions · v1.0
Duration = distance ÷ speed ÷ 24. Daily propulsion fuel scales with the cube of speed relative to the reference. Total fuel = daily fuel × duration. CO₂ = total fuel × the user-supplied factor. The default factor of 3.114 corresponds to a commonly used heavy fuel oil conversion factor; confirm the actual fuel before use.
No lifecycle emissions, methane slip, NOₓ or other greenhouse gases are included. The result is CO₂, not CO₂e. No emissions avoidance is recorded in the impact ledger.
IMO calculation reference