Ship Builders
O & K Tagebau u. Schiffstechnik
- Lübeck, Germany
Ocea Shipbuilding
- les Sables d'Olonne, France
Oceanfast Marine
- Fremantle, Australia
Odense Staalskibsværft
- Lindø, Denmark
Stocznia Odra
- Szczecin, Poland
Schiffswerft Johann Ölkers
- Hamburg, Germany
Offshore Steel Boats
- Barton upon Humber, United Kingdom
Sudostroitelnyy Zavod "Okean"
- Mykolayiv, Ukraine
Santierul Naval Oltenita
- Oltenita, Romania
Oma Båtbyggeri
- Stord, Norway
Onomichi Zosen
- Onomichi, Japan
Ørens Mekaniske Verksted
- Trondheim, Norway
Orenstein & Koppel
- Lübeck, Germany
Öresundsvarvet
- Landskrona, Sweden
Cantiere Navale Fratelli Orlando
- Livorno, Italy
Ørskov Christensens Staalskibsværft
- Frederikshavn, Denmark
Santierul Naval Orsova
- Orșova, Romania
William Osborne
- Littlehampton, United Kingdom
Oshima Shipbuilding Co.
- Oshima, Saikai and Yoshiumi, Japan
Oskarshamns Varv
- Oskarshamn, Sweden
Oyster Marine
- Ipswich, United Kingdom