Start with the cargo, not the shape of the pile
For a solid bulk fixture, “trimming required” is not a complete loading instruction. The IMSBC Code distinguishes cohesive from non-cohesive cargoes when setting out trimming provisions. Angle of repose is a characteristic used for non-cohesive cargoes; the Code says it is not an indicator of the stability of a cohesive cargo. That distinction matters before anyone tries to turn a reported angle into a target shape for a loaded hold.
The Code’s general trimming provision says cargoes shall be trimmed reasonably level, as necessary, to reduce the likelihood of shifting and minimize air entering the cargo, which could lead to spontaneous heating. It also gives the master the right to require level trimming where available information raises a stability concern, taking account of the ship and intended voyage. The angle-based provisions therefore need to be read alongside the general provisions and the cargo’s individual schedule, not as a stand-alone permission to leave a particular pile.
Read the angle as a category, not a surface measurement
The angle of repose establishes which of the Code’s provisions for non-cohesive cargoes applies. It is a property of the material determined by an appropriate test method; it is not the same measurement as the height difference across the cargo surface after loading. The Code requires the angle to be measured by a method approved by the appropriate authority. Its recommended methods include a tilting-box method for suitable granular material and an alternative shipboard procedure that gives an approximate angle when a tilting box is unavailable.
Cargo information supplied before loading includes the need for trimming and the trimming procedures, as necessary, and the likelihood of shifting, including angle of repose where applicable. A useful practical check—not an additional Code requirement—is to put the cargo information beside the proposed loading instructions and identify which angle category those instructions assume. If the information does not support that choice, resolve the category rather than treating the visible slope of a stockpile as a substitute for the required cargo information.
At or below 30°: understand the grain reference
For a non-cohesive cargo with an angle of repose of 30° or less, the IMSBC Code says it flows freely like grain and shall be carried according to the provisions applicable to the stowage of grain cargoes. It also requires the cargo’s bulk density to be considered when determining the scantlings and securing arrangements of divisions and bin bulkheads, and the stability effect of free cargo surfaces. This category is not governed by the finished-surface height limits stated for the two higher-angle categories.
That reference must not be mistaken for a claim that the cargo has become grain or that bulk grain falls within the IMSBC Code. The IMO explicitly says the IMSBC Code does not cover carriage of grain in bulk; grain has its own International Grain Code. Here, the IMSBC provision directs how a freely flowing non-cohesive cargo is to be carried by referring to rules applicable to grain stowage. Identifying the cargo correctly remains the first step.
Resolution MSC.539(107): 2023 Amendments to the International Maritime Solid Bulk Cargoes (IMSBC) Code · International Maritime Solid Bulk Cargoes (IMSBC) Code
Above 30°: calculate the height limit correctly
For an angle greater than 30° and up to and including 35°, the Code provides two alternatives: trim so that the vertical difference between the highest and lowest levels of the cargo surface does not exceed one-tenth of the ship’s beam, subject to an absolute maximum of 1.5 metres; or load using trimming equipment approved by the competent authority. For an angle greater than 35°, the same one-tenth-of-beam test applies, but the absolute maximum is 2 metres. The approved-equipment alternative also appears in that category.
The limit is the smaller of B/10 and the applicable maximum, not whichever figure permits a taller difference. For illustration, a 12-metre beam gives B/10 of 1.2 metres, so 1.2 metres is the numerical surface-difference limit in either higher-angle category if that route is used. At a 20-metre beam, B/10 is 2 metres: the limit is then 1.5 metres for an angle above 30° through 35°, and 2 metres for an angle above 35°. These are illustrations of the Code’s arithmetic, not measurements or permissions for a particular ship or cargo.
Turn the rule into a loading instruction
A practical handover can state the identified cargo, whether it is cohesive or non-cohesive, the applicable angle category, and which of the Code’s permitted trimming routes is intended. If the route uses a surface-height limit, state both B/10 and the applicable cap so the controlling number is explicit. If it relies on approved trimming equipment instead, distinguish that alternative from an assumed exemption from trimming. These are suggested ways to communicate the Code’s criteria; they are not additional documentary requirements imposed by the cited trimming provisions.
Finally, keep the trimming decision connected to the broader cargo assessment. The IMO identifies improper distribution and consequent structural damage, reduced stability, and cargo chemical reactions among the principal solid-bulk hazards. The IMSBC Code’s general provisions likewise address distribution and loading on the ship’s structure. Meeting an angle-based surface criterion answers a specific trimming question; it does not, by itself, settle every question about the cargo’s properties, its distribution or its safe carriage.
Resolution MSC.539(107): 2023 Amendments to the International Maritime Solid Bulk Cargoes (IMSBC) Code · International Maritime Solid Bulk Cargoes (IMSBC) Code