, ▁keeping ▁the ▁engine ▁load ▁between ▁ 6 0 - 8 0 %. ▁ ▁The ▁set - up ▁depends ▁on ▁the ▁D P ▁class ▁of ▁the ▁ship . ▁A ▁Class ▁ 1 ▁can ▁be ▁relatively ▁simple , ▁whereas ▁the ▁system ▁of ▁a ▁Class ▁ 3 ▁ship ▁is ▁quite ▁complex . ▁On ▁Class ▁ 2 ▁and ▁ 3 ▁ships , ▁all ▁computers ▁and ▁reference ▁systems ▁should ▁be ▁power ed ▁through ▁a ▁U PS . ▁ ▁Class ▁requirements ▁Based ▁on ▁I MO ▁( Intern ational ▁Mar itime ▁Organ ization ) ▁publication ▁ 6 4 5 ▁the ▁Classification ▁Soci eties ▁have ▁issued ▁rules ▁for ▁Dynamic ▁Position ed ▁Sh ips ▁described ▁as ▁Class ▁ 1 , ▁Class ▁ 2 ▁and ▁Class ▁ 3 . ▁ ▁Equ ip ment ▁Class ▁ 1 ▁has ▁no ▁redund ancy . L oss ▁of ▁position ▁may ▁occur ▁in ▁the ▁event ▁of ▁a ▁single ▁fault . ▁Equ ip ment ▁Class ▁ 2 ▁has ▁redund ancy ▁so ▁that ▁no ▁single ▁fault ▁in ▁an ▁active ▁system ▁will ▁cause ▁the ▁system ▁to ▁fail . L oss ▁of ▁position ▁should ▁not ▁occur ▁from ▁a ▁single ▁fault ▁of ▁an ▁active ▁component ▁or ▁system ▁such ▁as ▁gener ators , ▁thr uster , ▁switch boards , ▁remote ▁controlled ▁val ves ▁etc ., ▁but ▁may ▁occur ▁after ▁failure ▁of ▁a ▁static ▁component ▁such ▁as ▁c ables , ▁pip es , ▁manual ▁val ves ▁etc . ▁Equ ip ment ▁Class ▁ 3 ▁which ▁also ▁has ▁to ▁with stand ▁fire ▁or ▁flo od ▁in ▁any ▁one ▁compart ment ▁without ▁the ▁system ▁failing .