Ship Construction by Type of Vessel - Part 1

Several basic ship types are considered. The particular features of appearance, construction, layout, size, etc., will be examined for the following ship types:
(1) General cargo ships.
(2) Tankers.
(3) Bulk carriers.
(4) Container ships.
(5) Passenger ships.

General cargo ships

1. The general cargo consists of as large a clear open cargo-carrying space as possible, together with the facilities required for loading and unloading the cargo.
2. Access to the cargo storage areas or holds is provided by openings in the deck called hatches. Hatches are made as large as strength considerations will allow to reduce horizontal movement of cargo within the ship.
3. Hatch covers of wood or steel, as in most modern ships, are used to close the hatch openings when the ship is at sea. The hatch covers are made watertight and lie upon coamings around the hatch which are set some distance from the upper or weather deck to reduce the risk of flooding in heavy seas.
4. One or more separate decks are fitted in the cargo holds and are known as tween decks. Greater flexibility in loading and unloading, together with cargo segregation and improved stability, are possible using the tween deck spaces.
5. Various combinations of derricks, winches and deck cranes are used for the handling of cargo.
6. The accommodation and machinery spaces are usually located with one hold between them and the aft peak bulkhead.

Tanker

1. The tanker is used to carry bulk liquid cargoes, the most common type being the oil tanker.
2. The oil tanker has the cargo-carrying section of the vessel split up into individual tanks by longitudinal and transverse bulkheads.
3. Double bottom or/and double sides or double hull is fitted in the cargo-carrying section of an oil tanker.
4. A pair of wing tanks are created by longitudinal bulkheads. These wing tanks helps reduces the free surface effect.
5. Large amounts of piping are to be seen on the deck running from the pump rooms to the discharge manifolds positioned at midships, port and starboard.                                                                                     
6. LNG tankers carry methane and other paraffin products obtained as byproduct of petroleum drilling operations. The gas is carried at atmospheric pressure and temperatures as low as -164°C in tanks of special materials, which can accept the low temperature. The tanks used may be prismatic, cylindrical or spherical in shape and selfsupporting or of membrane construction.
7. LPG tankers carry propane, butane, propylene, etc., which are extracted from natural gas. The gases are carried either fully pressurized, part pressurized part refrigerated or fully refrigerated. The fully pressurized tank operates at 18 bar and ambient temperature, the fully refrigerated tank at 0.25 bar and —50 C. Tank shapes are prismatic, spherical or cylindrical. Low temperature steels may be used on the hull where it acts as a secondary barrier.

 

Reference

Ship Construction Lectures; Prof. Khaled Atua