During the course of shipping business, you may have seen or come across the term “Lost Slots”.. In this article, I will explain what are Lost Slots and possible methods of calculation of lost slots..
I have written quite a few articles about Out of Gauge (OOG) Cargo. Let me jog your memory a bit.. OOG is cargo that cannot fit inside a General Purpose container and requires special containers such as Open Top containers (OT) or Flat Rack containers (FR) or Platform containers due to the nature and size of the cargo.
The design and carrying capacity of container ships are based on TEU (Twenty-Foot Equivalent Unit) specifications, which is 20 x 8 x 8.6 feet or 6 x 2.4 x 2.4 meters. That is the dimension of a single slot on board a container ship. These dimensions of the slots are fixed when the ship is designed and fittings are set such that the corner posts of the container sit on it and so that it may be secured to the deck.
In the below image, you can see how the deck of a container ship looks like with the securing points for containers to be placed on deck.
Any dimensions above 6 x 2.4 x 2.4 m will be considered as OOG and containers with such cargo will NOT fit within these dimensions. For example, if a cargo is loaded on a Flat Rack container (as shown below) and its dimensions are 6 x 3.4 x 3.4 m, the cargo will be over-wide and over-high by 1 meter respectively.
OOG cargoes are (and should be) generally packed in the center of the container for equal weight distribution, so we can assume that this cargo will be protruding over the width of the container by 0.5 meters on each side and 1 meter above the height of the container. If you look at the below image of a fully loaded ship, you can see how close the containers are loaded and you can see that there is no space for protrusion of any kind as the boxes are tightly stowed.
Therefore, if the above OOG container is loaded on deck, no containers can be loaded to the left, right, and on top of this container. If the shipping line has to load this OOG cargo with the above example, they may have to compromise loading a few other containers to the right, left, and above this container.
If we take the minimum of say 1 container on each side, it means that the shipping line is losing 3 slots on board the ship in order to accommodate this 1 container. This loss of space caused to the shipping line by this OOG cargo is called LOST SLOTS.
Because they are losing these 3 slots, naturally the shipping line will have to charge the shipper of this OOG cargo for these lost slots as they are losing revenue. The calculation of the number of lost slots and the cost for the same will depend on various factors like
- How full the ship is
- How many slots will be lost
- Where would be the most effective and easiest placement of this container to facilitate easy access for loading and discharge
- The port rotation of the ship
- Whether there will be any restows en route or not
A shipping line has to take all of this into account before they advise the client the details of the lost slots and its associated costs. This is also the reason that the shipping lines sometimes take a while to advise you the costs for OOG cargo, so please be patient.
OOG cargo is not restricted to on-deck loading only; it can also be loaded in the hold or containers stacked on top of each other. However, when calculating lost slots, we will focus primarily on deck-loading scenarios.
Killed Slot Matrix | PDF | Length | Metrology
This document provides information and guidelines for using an OOG calculator tool. It lists dimensional limitations for various equipment types that can be used when preparing bookings. It advises that if information provided during booking differs from actual cargo dimensions, the cargo may be rolled without reservation.
It provides measurement cells where dimensional data can be entered to determine loading conditions and displacement calculations.
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