Question 1

What real incident led the IMSBC Code to remove its "Ammonium Nitrate Based Fertilizer (Non-Hazardous)" schedule entirely in the 2022 edition?

Accepted Answer

MV CHESHIRE (2017) — cargo declared non-SSD-liable underwent apparent self-sustaining decomposition during passage from Norway to Thailand MV CHESHIRE's cargo was declared "Ammonium Nitrate Based Fertilizer (Non-Hazardous)" — specifically not liable to SSD — yet the vessel experienced rising hold temperatures and toxic gas generation consistent with apparent SSD during the 2017 voyage. The incident directly drove IMSBC's 2022 replacement of the single blanket schedule with two more specific ones (Group B MHB and Group C).

Question 2

The yacht is loading additional stores and fuel before a long passage, raising the displacement significantly. What effect does this have on stability that you, as OOW, should be aware of?

Accepted Answer

Increased displacement generally raises the centre of gravity if weight is added high up, and free surface effects in partially-filled tanks can reduce the effective metacentric height (GM) Adding weight changes the vessel's centre of gravity depending on where it is stowed, and partially-filled tanks create free surface effects that reduce GM. OOWs should understand these basic stability principles even on smaller vessels without a dedicated loading computer.

Question 3

During a survey, watertight door seals in a transverse bulkhead below the waterline are found to be perished and not closing properly. As Master, what is the significance of this for the vessel's damage stability?

Accepted Answer

Significant — a failed watertight closure compromises the subdivision the vessel's damage stability calculations rely on, potentially allowing progressive flooding between compartments in the event of damage Damage stability calculations assume watertight subdivision functions as designed. A bulkhead door that cannot seal properly defeats that subdivision, allowing flooding to spread beyond the single compartment the design assumed — this must be rectified before further operation.