Ice concentration is measured in tenths. What concentration range of ice corresponds to "Open Pack"?
Official USCG Answer & Rule Citation
Correct Answer: Option D — 4 - 6 tenths
WMO sea ice nomenclature defines "Open Pack" ice concentration within the range of 4 to 6 tenths. Navigators must exercise caution in these waters, as floes begin to coalesce and restrict direct maneuvering capability for unreinforced commercial hulls.
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