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Bulk cargo: stowage factor and cargo hold

How many tonnes can be loaded in the space?

Answer: With bulk cargo such as grain, fertiliser, timber pellets or gravel, you need to know whether the hold will be full before the ship is loaded to its draught. The stowage factor tells you how many cubic metres one tonne fills, and it is shown on the shipper's bill of lading. Light cargo fills the space before the weight limit. Heavy cargo reaches the weight limit while the space is still half empty. Broken stowage is deducted from the space for corners, hatches and uneven trimming. The calculator shows what determines it.

Formula

Tons efter volumen = rummets volumen × (1 − spild) ÷ stuvningsfaktor

Mulig last = den mindste af tons efter volumen og de tons, der er til rådighed i lasteplanen

Rumfang lasten fylder = mulig last × stuvningsfaktor

Eksempel: 6.000 m³ × 0,98 ÷ 1,5 m³/t = 3.920 t. Lasteplanen giver 5.000 t, så det er rummet, der bestemmer

Symbols and units in the formula
SymbolMeaningUnit
rum_m3Cargo space volume (from ship's capacity plan)m³
sfStowage factor (from shipper)m³/t
spild_pctWaste in space (broken stowage)%
vaegt_til_raadighedTons available for the load in the space (from the load plan)t
=Load that can go in the spacet
=Tons by volumet
=Volume occupied by loadm³
=Filling the space%

Validity and source

Source
Stowage factor (m³ per ton) from the shipper's cargo statement, cf. IMSBC Code

Does not apply when

  • The stowage factor varies with moisture, grain size and trimming, so always use the shipper's figure for that particular cargo. The weight limit in the space comes from the ship's loading plan (draught, trim, strength) and is set by the ship's officers, not the calculator. Grain is regulated by IMO's Grain Code.

Worked example

The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.

Substituted

  • Cargo space volume (from ship's capacity plan)6,000 m³
  • Stowage factor (from shipper)1.50 m³/t
  • Waste in space (broken stowage)2 %
  • Tons available for the load in the space (from the load plan)5,000 t

Giver

  • Load that can go in the space3,920 t
  • Tons by volume3,920 t
  • Volume occupied by load5,880 m³
  • Filling the space98 %

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Sådan bruger du den

Du bruger den, når et bulkskib skal lastes med korn, gødning, træpiller eller grus, og du vil vide, om rummet bliver fuldt, før vægtgrænsen er nået.

Step by step

  1. Find rummets volumen i skibets kapacitetsplan.
  2. Få stuvningsfaktoren fra afskiberen.
  3. Træk spild fra, og del med stuvningsfaktoren.
  4. Sammenlign med de tons, lasteplanen giver til rummet. Det mindste bestemmer.

Typical errors

  • At bruge stuvningsfaktor i ft³ pr. long ton som m³ pr. t.
  • At glemme spild ved luger og hjørner.
  • At bruge volumen-tons uden at spørge skibet om vægtgrænsen.

Examples from everyday life

Træpiller i et lastrum

Et rum på 6.000 m³ skal lastes med træpiller. Afskiberen oplyser stuvningsfaktor 1,5 m³/t. Spildet er 2 %, og lasteplanen giver 5.000 t til rummet.

Cargo space volume (from ship's capacity plan)
6,000 m³
Stowage factor (from shipper)
1.5 m³/t
Waste in space (broken stowage)
2 %
Tons available for the load in the space (from the load plan)
5,000 h

It means: Rummet kan tage 3,920 h, og lasten fylder 5,880 m³, altså 98 %. Det er rummet, der bestemmer, ikke vægten.

Tungt grus i samme rum

Rummet skal i stedet have grus med stuvningsfaktor 0,6 m³/t og 1 % spild.

Cargo space volume (from ship's capacity plan)
6,000 m³
Stowage factor (from shipper)
0.6 m³/t
Waste in space (broken stowage)
1 %
Tons available for the load in the space (from the load plan)
5,000 h

It means: Efter volumen kunne der være 9,900 h, men lasteplanen giver kun 5,000 h. Lasten fylder 3,000 m³, altså 50 %. Grus skal trimmes, så vægten fordeles.

Rule of thumb

Tunge laster med lav stuvningsfaktor, som malm og grus, rammer vægtgrænsen først. Lette laster, som træpiller, fylder rummet først.

How to check the answer

Mulig last × stuvningsfaktor må aldrig være større end rummets volumen.