Deadweight cargo capacity Calculation

Deadweight Cargo Capacity Calculation

1. New DWT:

The MV “XXXXX” has DWT 56.838mt and 12,82 m SSW draft. However, we have draft limitation @ Itacoatiara. So:

(MV XXXXX Draft) – (Itacoatiara FW Draft) =

12,82 m – 11,5 m = 1,32 m = 132 cm

Then,

132 cm x (TPC = 58,8mt) = 7.761,60mt

New DWT = 56.838 – 7.761,60 = 49.076,4mt

Unfortunately, this is not correct. As we have seen before, the water density impacts on the DWT.

Typical load lines for a vessel.

When the vessel reaches the sea water it will rise to the summer load line level. It is important to take advantage of the FWA because there will be a loss of cargo carried, and therefore a loss of revenue, if the vessel only loads up to the summer load line level in freshwater. In this example, the draft given is for FW. So, our draft limitation is even worst. 

So, we have to re-calculate the draft limitation to SSW:

11,50 ÷ 1,025 = 11,22 m, SSW draft.

The New DWT is 56.838mt – (12,82 m – 11,22 m x 58,8mt/cm) = 47.430mt

2. Time Duration:

Laden: Distance ÷ (Speed x 24h) =

          6.017 nm ÷ (14 knots x 24h)  = 17,9 days

Loading Port: 45.000mt ÷ 4.000 = 11,25 days

Discharge Port: 45.000mt ÷ 4.500 = 10 days

Total: 39,15 days

3. Bunkering Consumption:

Laden: 17,9 days x 34mt = 608,6mt IFO                

          17,9 days x 0,3mt = 5,37mt MDO

Loading Port: 11,25 days x 4,8mt = 54mt IFO

Discharge Port: 10 days x 4,8mt = 48mt IFO

Total ~ 716 mt.

We add 5% as a safety margin, then 787,6mt of fuel.

4. New DWCC:

DWT: 47.430mt

 ·         787,6mt Bunkering

 ·         465 mt Freshwater

 ·         400 Constant

The New DWCC is 45.777,4mt

This will be our new DWCC. Stay tuned, soon I’ll add more examples on MWOC covering different loading situations.