Hereafter, "sensitive vertical lines" means the vertical lines within one container space from a gap in athwart-ship direction. Based on such understanding, we propose a new principle for vertical segregation as follows:
(1) When a reference container packed with dangerous liquids is stowed on a hatchway cover and "not in the same vertical line unless segregated by a deck" is required for a container packed with incompatible goods, the container packed with incompatible goods should not be stowed in relevant sensitive vertical lines in the cargo hold.
The gaps of hatchway covers are located just between the vertical lines of containers, in general. In other words, the sensitive vertical lines for one gap include two rows on and under the hatchway covers, in general.
When a container packed with dangerous goods was stowed under hatchway covers in a vertical line near a gap, flame could pass through the gap in case of fire of the container. In such case, flame may reach containers on the hatchway covers stowed in vertical lines near the gap. It is deemed, however, when a container packed with dangerous goods was stowed under deck in vertical lines not near a gap, fire of the container could not affect the containers on hatchway covers. Furthermore, even in case of fire in a container stowed under deck in a vertical line near a gap, the probability of propagation of fire to the dangerous goods in the containers stowed on hatchway covers in vertical lines not located near the gap is small. Based on such understanding, we propose a new principle for vertical segregation as follows:
(2) When a reference container is stowed in a sensitive vertical line under hatchway covers and "not in the same vertical line unless segregated by a deck" is required br a container packed with incompatible goods, the container packed with incompatible goods should not be stowed in relevant sensitive vertical lines on the hatchway covers.
5.2 Interpretation of "not in the same vertical line unless segregated by a deck"
Based on the above mentioned principles, the words "not in the same vertical line unless segregated by a deck" for vertical segregation on container ships with partially weatherproof hatchway covers can be interpreted as illustrated in Figures 1-1 to 1-6.
Figure 1-1 illustrates the principle (1) in paragraph 5.1. The legends of this figure are common to all figures. In this figure, it is assumed that the reference container is packed with dangerous liquids. Figure 1-2 also illustrates the principle (1) in paragraph 5.1. In this figure, it is assumed that the reference container is packed with dangerous solids or gases. Figure 1-3 illustrates the principle described in paragraph 3.2. Where a reference container is stowed in a vertical line not on a hatchway cover on deck, segregation is not required in the cargo hold. Figure 1-4 illustrates the principle (2) in paragraph 5.1. In this figure, the reference container is stowed in a vertical line other than sensitive vertical lines. Figure 1-5 illustrates the principle (1) in paragraph 5.1, when the reference container is stowed on a centre hatchway cover. Figure 1-6 illustrates the principle (1) and (2) in paragraph 5.1. By these principles, when the reference container is stowed in a sensitive vertical line in a cargo hold and "not in the same vertical line unless segregated by a deck" is required for a container packed with incompatible goods, containers packed with incompatible solids or gases NOT permitted and containers packed with incompatible liquids NOT permitted become as illustrated in both left and right figures respectively.
