Your examiner asks: "What stability criteria apply when carrying grain, and what documents must be on board?" Give a complete answer covering the International Grain Code.

A. The International Grain Code (IMO Res. MSC.23(59)) applies to all vessels carrying grain in bulk. Requirements: the angle of heel after a grain shift must not exceed 12 degrees; the residual area between the heeling moment curve and the righting moment curve (between angle of heel after shift and the angle of flooding or 40 degrees, whichever is less) must be at least 0.075 metre-radians; GM must not be less than 0.30 metres at departure. Documents: Document of Authorisation to carry grain (or approved grain loading plan), Grain Loading Booklet, stability calculation for each loaded condition.

B. The Grain Code requires GM to be at least 1.0 metre at all times. No specific angle of heel criterion applies — only the GM limit.

C. Grain is carried under the IMSBC Code. The Grain Code was superseded in 2010 and no longer applies to vessels built after that date.

D. No special stability criteria apply to grain — the standard IS Code 2008 criteria cover all bulk cargoes including grain.

A. GM (metacentric height) is the distance between the centre of gravity (G) and the metacentre (M). A positive GM (M above G) indicates stable equilibrium — the vessel will right itself when heeled. A very low GM risks loll, slow period of roll, and potential capsize. A very high GM (stiff ship) causes a rapid, violent rolling motion that can create excessive dynamic loads on cargo, structures, and crew — which can be as dangerous as low stability.

B. GM is always a positive value. A negative GM means the ship is overloaded and must discharge cargo immediately.

C. GM is the distance between the keel and the metacentre. A higher GM always means a safer, more stable vessel regardless of its magnitude.

D. GM only applies to loaded conditions. In ballast, stability is assessed using only the KG value.

A. Key GZ curve features: range of stability (angle at which GZ returns to zero); maximum GZ and angle of maximum GZ; area under the curve (dynamical stability). IMO IS Code 2008 criteria: area 0-30 degrees minimum 0.055 metre-radians; area 0-40 degrees (or to flooding angle if less than 40) minimum 0.090 metre-radians; area 30-40 degrees minimum 0.030 metre-radians; maximum GZ at least 0.200 metres at 30 degrees or greater; initial GM not less than 0.150 metres.

B. The minimum GM under all criteria is 0.5 metres. The GZ curve must reach a maximum of at least 0.5m at any angle between 20 and 60 degrees.

C. The only IMO requirement is that the angle of vanishing stability must exceed 60 degrees. Area under the curve and initial GM are national flag state requirements only.

D. The IMO IS Code applies to new vessels only. Older vessels built before 2010 comply with the 1966 Load Lines convention stability requirements only.