Abstract: There is provided a tanker for carrying petroleum products, including crude oil, chemicals or other potentially environmentally harmful materials, having an inner hull and an outer hull and where the void between the inner hull and outer hull at the bottom of the tanker is at or near the minimum spacing required by U.S. and international regulations. The tanker has side tanks for holding ballast, which extend upward from near to or above the ballast water line. The dimensions of each side tank are large enough to hold a sufficient volume of ballast water to keep the tanker in ballast condition meeting U.S. and international regulations for ballast draft. The cross-sectional shape of the side tank is substantially rectangular in the preferred embodiment, although other shapes to most efficiently utilize the space available on the tanker ship also can be used.