Complex sentence: The Jeddah sailed under the British flag was crewed largely by British officers but was owned by the Singapore Steamship Company, whose managing director Seyyid Muhammad al-Sagoff came from a wealthy Arab family well established in Singapore.
Split into simpler sentences: The Jeddah sailed under the British flag and was crewed largely by British officers. It was owned by the Singapore Steamship Company, whose managing director, Seyyid Muhammad al-Sagoff, came from a wealthy Arab family well established in Singapore.