Home NI621 Guidelines for moonpool assessment NI621 provides guidance for structural assessment of any vessel fitted with a moonpool (drilling ship, offshore service vessel, floating offshore unit, scientific vessel). Reference Title Edition NI621 R00 Guidelines for moonpool assessment Jan 2016 check related documents: NR569 Classification of drilling ships NR467 Rules for the classification of steel ships NR445 Rules for the classification of offshore units Check other Bureau Veritas rules and guidelines.