Void Space Calculation (Over-length)

If the cargo exceeds a length of 11.6 to 11.7 meters, the front and rear corner posts(end walls) of a 40' flat rack can be laid flat. This forms a flatbed onto which the cargo can be loaded. 

However, if the length of the cargo, once loaded onto the flatbed, exceeds 12,192 mm (which is the length of the 40'FR), it will protrude both forward and backward beyond the dimensions of the 40'FR. This condition is termed 'Over-length,' and any cargo in this state is referred to as 'Over-length Cargo.' 

[Over-length criteria of 40'FR]

Calculating the VOID Space for Over-length cargo can be complex due to the limited stowage space on container ships. Therefore, even an approximate VOID should be confirmed with the carrier, as illustrated in the table below.

	20’ Flat Rack	40’ Flat Rack
Over-height	= Cargo height	= Cargo height
Over-length	L > 6,058 mm (Recommend switching to 40’FR)	L 12,192 mm
Void Space	Min. 1 TEU ~ Max. 5 TEU or more	Min. 2 TEU ~ Max. 10 TEU or more

Now, let's take an example to illustrate the VOID calculation for an over-length cargo. In the image below, boxes of 16 meters in length are loaded onto a 40'flat bed and loaded as over-length cargo on a container ship. With the 40'FR measuring 12,192 mm in length, the boxes protrude 1,904 mm both forward and backward, resulting in over-length. 

[Over-length cargo loaded on container ship]

VOID is a slot on the container ship that cannot accommodate another container due to the out-gauge. Hence, a VOID can occur as follows:

① VOID due to OH (Over-height): 2 TEU

② VOID due to OF (Over-forward): 2 TEU

③ VOID due to OB (Over-backward): 2 TEU

Total VOID Space: 6 TEU

Looking at the image, you can observe the space behind the 40'FR left vacant as it couldn't be filled with another container - this is the VOID Space.

The shipment's VOID has been determined to be 6 TEUs to be accounted for in the freight rate. However, the VOID can further increase depending on the loading conditions of the container vessel.

The image below depicts that the slots in front of, behind, and above the container account for a total of 6 TEUs of VOID Space that cannot be filled with another container.

[Void Space of Over-length cargo]

However, if this over-length cargo needs to be stowed on the lower tier of the on-deck for cargo handling, the slots that cannot be stowed vertically will naturally increase. This results in 6 TEU + 4 TEU, escalating the VOID to 10 TEU. Furthermore, if the stowage location demands that the ship be loaded on the first tier of the on-deck, the VOID might increase by an additional + 4 TEU in consecutive stages.