I was overseeing a bulk carrier self-discharging cargo by deck cranes and grabs. Being the rainy season, the crew had opened only the after half of the hatch covers.
This is an unsafe practice, as there is an unacceptable risk of the grab hitting and damaging the exposed end of the closed hatch cover. Such damage can impair the hatch cover’s weathertightness and can render the vessel unseaworthy.
Furthermore, it must be remembered that effective repairs to hatch covers and associated sealing devices always involves high cost, delays, special materials, equipment and skills. In the case of dry bulk cargoes that can be poured or pumped, vessels can often work such granular or free-flowing cargoes in rain with hatches closed, leaving a small section open for the cargo line(s) or pipe(s).
However, when grabs are in use, it is strongly suggested that, if a cargo is susceptible to damage by rain, snow or precipitation, the vessel should opt to discontinue cargo operations altogether during inclement weather and avoid working cargo through partially open hatchways.