5.1.2 To minimize the risk of shifting, cargoes should be trimmed reasonably.
5.1.3 Cargo spaces should be filled as full as practicable without resulting in an excessive mass of the material on the bottom structure or tween-deck. Cargo should be spread widely to the boundary of the cargo space as far as practical.
5.1.4 Taking the cargo information into consideration, if any circumstances of doubt on cargo shift by the master, the cargo should be trimmed effectively level by means of available methods, e,g,, loading spouts or chutes, portable machinery, equipment or manual labor."
(11) Paragraph 5.2.4.1 - Editorial
Re: Section 6
No comment.
Re: Section 7
(12) Paragraph 7.1 - Editorial
The new part "Movement of bulk cargoes" should be incorporated into existing paragraph 7.1.
Re: "Movement of bulk cargoes"
(13) Heading
If necessary, I propose the words "Cargo shifting" or "Liquefaction" as the heading of this paragraph.
(14) 1st and 2nd paragraphs
The following paragraphs should be deleted because this paragraph is not fit for this section. The sentences in these paragraphs can be incorporated in section 5.
"Cargoes may move in a variety of ways. When a dry bulk cargo is piled, it stays in a pile unless some force acts on it to make it move. The edges of the pile form a natural angle to the horizontal at which they are stable and do not slip. This angle is termed the angle of repose. Free flowing or non-cohesive materials have small angles of repose, and may move easily with small angles of heel unless trimmed flat and secured or the compartment is filled. Grain, although not an ore or a concentrate is a classic cargo of this type. The movement is termed sliding failure and is due to a lack of shear strength in the material. In a dry, free flowing cargo with a low angle of repose, the cargo will flow when the roll angle exceeds that of the angle of repose.
Other cargoes resist movements because they are highly cohesive, fine particles or granular materials with high internal friction. For a cargo of these types to move the cohesive or friction forces must be overcome. The energy for this is readily available in a seaway; the combination of vibration and ship movements such as rolling, pitching and heaving."
(15) 3rd paragraph
The first sentence in the following paragraph should be deleted because this paragraph is not fit for this section. The second sentence can be incorporated into paragraph 7.1. (refer to the comment No.20)
"Cargoes can also slide, often with catastrophic results, if they are not trimmed out to the ship's side and the friction forces between the cargo and the tank top are overcome. The phenomenon may occur even with trimmed cargoes, particularly if the cargo is shallow in depth and subject to large heel angles."
(16) 4th to 7th paragraphs
The following paragraphs can be substituted by the other explanation. (refer to the comment No.20)
The typical phenomenon of liquefaction is the decrease of friction of the material due to increase of pore pressure. However, it should be noted that such phenomenon does not take place in some materials categorized into Group A such as "fish" or "peat moss".
"Granular materials such as dry bulk cargoes have void spaces between the particles caused by the shape of the particles; they do not form a regular fit. The void spaces may contain air, water or a combination of both.
When a cargo containing moisture is subjected to energy such as ship motions, the cargo particles move in small amounts, compressing the void spaces and pressurizing any moisture that might be present. If the amount of pressure becomes too high, it overcomes the friction forces between the particles, liquefaction occurs and the cargo flows.
