Overseas Shipholding Extends Charters for American Shipping Company’s Tanker Quartet 12 December 2019 OSG has exercised options to extend its bareboat charter deals for four AMSC tankers.Author: Capt. Johnhttps://worldmaritimenews.com/archives/287890/overseas-shipholding-extends-charters-for-american-shipping-companys-tanker-quartet/