Onassis built up a fleet of freighters and tankers that eventually exceeded seventy vessels. The strait also experiences significant amounts of international commercial shipping traffic by freighters and tankers. Evergreen proposed to convert up to four of its Boeing 747-200 Freighters into Supertankers. Also in 1947 the company commissioned five freighters and two cargo liners. In 2008 Norilsk Nickel ordered five new ice-breaking cargo freighters. Glencore is also a co-owner of large coal freighters fleet SwissMarine. Only a few aircraft were delivered as pure freighters. The new Superfreighters joined a fleet of nine standard Mark 21 Freighters. It converts old 737-800 passenger jets to dedicated freighters. The SkyCargo division operates 13 Boeing 777 Freighters. The airline also plans to retire the 747 freighters when the 777 freighters are delivered. Despite these hazards, she damaged several freighters and an enemy submarine. In early 2010, Southern Air took delivery of two Boeing 777 freighters. In early 2015 a contract was being negotiated for another 3 Boeing 747-8 freighters. Civilian operators typically operated the type as freighters.