Mid Ship Section of Double Hull Oil Tanker:
A mid ship section of a double hull oil tanker is a cross-sectional view of the ship’s structure at the middle of its length. It shows the arrangement and dimensions of the different parts of the hull, such as the plating, stiffeners, bulkheads, tanks, etc.
The above figure is the midship section of a double hull tanker. The right half of the drawing shows an ordinary frame, where the outer and inner hull plates are longitudinally framed.
A double hull oil tanker has an inner and an outer hull, separated by a space that can be used for ballast water or cargo oil. The inner hull forms the centre tank and the wing tanks, while the outer hull forms the side shell and the bottom shell.
The centre tank is used for storing cargo oil, and the wing tanks are used for carrying sea water ballast or cargo oil. The wing tanks are also called segregated ballast tanks (SBTs) because they are separated from the cargo oil tanks by longitudinal bulkheads.
The SBTs are coated with epoxy to prevent corrosion from seawater. The double bottom spaces are also used for water ballast, and they provide protection to the cargo tanks in case of grounding.
A double hull oil tanker has a higher resistance to damage from collision or grounding than a single hull tanker, and it reduces the risk of oil spillage and pollution.
The centre tank and the wing tank are separated by horizontal bulkheads, which divide them into upper and lower tanks. The upper tanks are used for ballast water, and the lower tanks are used for cargo oil. The centre tank and the wing tank have different advantages and disadvantages in terms of safety, efficiency, and maintenance.