▁ports . ▁ ▁App lications ▁ ▁Import ant ▁applications ▁include : ▁Serv icing ▁A ids ▁to ▁Navigation ▁( AT ON ) ▁C able - lay ing ▁C rane ▁vessels ▁Cru ise ▁ships ▁D iving ▁support ▁vessels ▁D red ging ▁Dr ill ships ▁Flo ating ▁production ▁storage ▁and ▁off loading ▁units ▁( FP SO s ) ▁Fl ot els ▁Land ing ▁platform ▁do cks ▁Mar itime ▁research ▁Mine ▁swe ep ers ▁Pi pe - lay ing ▁ship ▁Platform ▁supply ▁vessels ▁Rock ▁dump ing ▁Sea ▁La unch ▁Sea - based ▁X - band ▁rad ar ▁Sh utt le ▁tank ers ▁Survey ▁ships ▁ ▁S cope ▁ ▁A ▁ship ▁can ▁be ▁considered ▁to ▁have ▁six ▁degrees ▁of ▁freedom ▁in ▁its ▁motion , ▁i . e ., ▁it ▁can ▁move ▁in ▁any ▁of ▁six ▁axes . ▁ ▁Three ▁of ▁these ▁involve ▁translation : ▁sur ge ▁( forward / astern ) ▁s way ▁( star board / port ) ▁he ave ▁( up / down ) ▁ ▁and ▁the ▁other ▁three ▁rotation : ▁roll ▁( rot ation ▁about ▁s way ▁axis ) ▁pitch ▁( rot ation ▁about ▁he ave ▁axis ) ▁y aw ▁( rot ation ▁about ▁heading ▁axis ) ▁ ▁Dynamic ▁position ing ▁is ▁concerned ▁primarily ▁with ▁control ▁of ▁the ▁ship ▁in ▁the ▁horizontal ▁plane , ▁i . e ., ▁the ▁three ▁axes : ▁sur ge , ▁s way ▁and ▁y aw . ▁ ▁Re quire ments ▁ ▁A ▁ship ▁that ▁is ▁to ▁be ▁used ▁for ▁D P ▁requires : ▁to ▁maintain ▁position ▁and ▁heading , ▁first