| | Name of ship | GRT | | | O.A. Brodin | 1,960 | | | O.A. Knudsen | 11,007 | | | Oakbank | 5,154 | | | Oakcrest | 5,407 | | | Oakdene | 4,255 | | | Oakmar | 5,766 | | | Oakton | 1,727 | | | Oaxaca | 4,351 | | | Oberon | 1,996 | | | Observer | 5,881 | | | Ocana | 6,256 | | | Ocean Courage | 7,173 | | | Ocean Crusader | 7,178 | | | Ocean Justice | 7,173 | | | Ocean Might | 7,173 | | | Ocean Seaman | 7,178 | | | Ocean Vagabond | 7,174 | | | Ocean Vanguard | 7,174 | | | Ocean Venture | 7,174 | | | Ocean Venus | 7,174 | | | Ocean Viceroy | 7,174 | | | Ocean Victor | 202 | | | Ocean Voice | 7,174 | | | Octavian | 1,345 | | | Ogontz | 5,037 | | | Ohioan | 6,078 | | | Oilfield | 8,516 | | | Oituz | 2,686 | | | Oklahoma | 9,298 | | | Oklahoma | 9,264 | | | Olaf Fostenes | 2,994 | | | Olancho | 2,493 | | | Olean | 7,118 | | | Olga | 2,496 | | | Olga E. Embiricos | 4,677 | | | Oligarch | 6,894 | | | Olinda | 4,053 | | | Olivegrove | 4,060 | | | Oliver Ellsworth | 7,191 | | | Olopana | 6,069 | | | Oltenia II | 6,394 | | | Olympic | 5,335 | | | Omar el Kattab | 38 | | | Onega | 1,603 | | | Oneida | 2,309 | | | Onondaga | 2,309 | | | Ontario | 3,099 | | | Ontario | 490 | | | Onto | 1,333 | | | Ootmarsum | 3,628 | | | Opalia | 6,195 | | | Opawa | 10,354 | | | Oporto | 2,352 | | | Orangemoor | 5,775 | | | Orania | 1,854 | | | Oranjestad | 2,396 | | | Orari | 10,350 | | | Orcades | 23,456 | | | Oregon | 6,008 | | | Oregon | 7,017 | | | Oregon Express | 3,642 | | | Orfor | 6,578 | | | Oriskany | 1,644 | | | Orminster | 5,712 | | | Oropesa | 14,118 | | | Oropos | 4,474 | | | ORP Orkan | 1,920 | | | Orsa | 1,478 | | | Osmed | 1,526 | | | Otaio | 10,298 | | | Otho | 4,839 | | | Otina | 6,217 | | | Otterpool | 4,876 | | | Oued Grou | 792 | | | Ove Toft | 2,135 | | | Ozório | 2,730 | | means we have a picture of this vessel. |
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