During a night watch in waters with occasional reported ice, the lookout reports that ice (particularly low, dark, weathered ice or small bergy bits) is genuinely difficult to distinguish from open water at the current visibility and lighting. What should the OOW do?

A. Continue at the previously planned speed since the lookout has already been briefed to watch carefully

B. Treat this as a serious limitation on the watch's actual detection capability and respond accordingly — reduce speed to increase available reaction time, increase the number of lookouts or use additional detection aids (radar tuned for ice, searchlights) if available, and brief the Master, rather than continuing at a speed that assumed full visual detection capability that does not actually exist in current conditions

C. No action is needed since "difficult to distinguish" is a normal and expected limitation requiring no operational response

D. The report can be disregarded since radar alone is normally sufficient for ice detection regardless of visual conditions

A. All sea ice types present identical risk to a vessel's hull regardless of age or thickness

B. Each ice type has a different thickness, hardness, and likely behaviour when the vessel's hull contacts it — multi-year ice is far harder and more dangerous than first-year ice of similar visual appearance, and precise terminology allows the Master and ice navigator to make an accurate risk judgement rather than relying on a vague, potentially misleading general description

C. Ice terminology is purely academic and has no bearing on operational decision-making

D. Precise ice terminology is only relevant to icebreaker crews, not to merchant vessel watchkeepers

A. Speed reduction in ice is only a consideration for vessels with no ice class, never for ice-classed vessels

B. Speed should always increase in higher ice concentration to push through the ice more efficiently

C. Ice concentration has no bearing on safe speed provided the vessel holds any ice class notation at all

D. Higher ice concentration reduces the time and distance available to recognise and avoid larger or harder ice features within the pack, and increases the cumulative impact loading on the hull from repeated contact — even an appropriately ice-classed vessel has a speed/concentration relationship beyond which the risk of structural damage or becoming beset increases significantly