2023 05 13 – Sonabia 2: sustainable fuel consumption


Sonabia 2:   boring figures

Antarctica February 5 to March 2, 2023
6 persons,1484 nautical miles (nm), i.e., 2750 km.
Total fuel consumption 671 liters, 232 engine hour.
Averages: 2.88 L/ engine hour, 0.45 liter / nautical mile,  0.38 kg/nautical mile, 0.063 g/ person x nm

64 grams of combustible per mile and person

This corresponds to a very low carbon footprint: why?

    • Sailboats under sail do not use the engine (wow, great thinking).
    • Under engine, low fuel consumption (relatively light boat, slow cruising speed, engine compliant with new European norms).
    • There is no luxury, no need to waste fuel for excessive heating, strong illumination, bubble baths, etc.

Cruising ships: boring figures

On modern cruising ships, hybrid propulsion (electric motors + fuel  or GPL generators) consume and contaminate less than classical heavy fuel engines [2].

Consumption figures are not public, however, here are safe estimates

For a small passenger ship, 200 passengers,in economical mode (observed on AIS: 13 knots in Antarctica)

Pessimistic estimate : 100 tons of fuel or equivalent per day. 
Source [1]. 
100 tons per day means 4167 kg/hour, 320 kg/nm, 1.6 kg/passenger x nm.

Optimistic estimate: 20 tons of fuel or equivalent per day.
Source. Consumption of modern cargo ships [3, table in 1], equivalence cargo ships - cruise ships of similar displacement, using a conversion factor 40% (gross tonnage vs. metric tons; data of several cruise ships available on the web)
20 tons per day means 833 kg/hour, 64 kg/nm, 320 g/passenger x nm.

320g to 1600g of combustible per mile and passenger

Clearly, passenger ships are not environment – friendly, even with modern propulsion systems. Actually, passengers ships consume more than cargo ships, for 2 reasons

    • Luxury.  Facilities like illumination, heating, unlimited hot water, restaurants, etc. require energy (produces by engines and/or auxiliary generators).
    • Speed. It is  necessary to push the engines to meet deadlines and arrive fast on the touristic spots (observed on AIS: often above 18-20 knots).

Environment friendly?  slow and rustic navigation

Sonabia 2: engine, Nanni 85HP, Euro norms.

Cruise ship: example of engine [2]


[1] https://www.marineinsight.com/know-more/how-much-fuel-does-a-cruise-ship-use/
[2] https://www.cruisemapper.com/wiki/752-cruise-ship-engine-propulsion-fuel
[3] https://maritimepage.com/fuel-consumption-how-much-fuel-cargo-ship-use/
[4] https://www.cruisemapper.com/wiki/753-cruise-ship-sizes-comparison-dimensions-length-weight-draft

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