Maritime Industry


Ships construction, stability, and trim


Ships characteristics


In the Maritime industry today there are many different kinds of ships that are made to do very different things in this paper I will discuss the more common of the types of ships and tell how they operate and ultimately what makes them the most popularly used in such a wide range of variety of ships the world sees today.


BREAK BULK CARRIERS


The cargo spaces and holds are separated by transverse bulkheads and the keel is fitted with a double bottom to prevent flooding to the spaces and the ship. Normally three to five cargo holds will be forward of the deck house and the machinery spaces and one to two holds aft. Each main cargo hold space consists of a deep lower hold just above the double bottom plus one or two tween decks above the holds. All holds are fitted with watertight hatches to prevent water from breaking the bow and flooding the holds. When cargo is put aboard a break bulk carrier despite the size of the hatches each individual piece of cargo must be manhandled or moved into the tight spaces of the ship with a forklift to preserve space and carry the most cargo possible to turn the biggest profit. Break bulk carriers are fitted with their own for of cargo gear to on and off load whether it be cargo booms fixed to masts and king posts or cranes that run on tracks up and down the side of the ship and side ports to make cargo handling easier. Break bulk carriers range in size from 430 – 560 feet in length, weigh anywhere from 12,000 – 17,000 tons and have a sustained sea speed of 14 – 25 knots.


CONTAINERSHIPS


Containerships have the basic ship construction as break bulk carriers with the exception of a few small things. Since the cargo is to move once it is in the ships hold the ship is equipped with its own system to properly distribute the containers below deck. These are called container cell guides and they are made of steel angled bars which prevent the standard container from jamming. They also have a much more economical approach in that containers are able to be stacked up on deck allowing a ship to carry much more cargo along with the reduction of cargo handling time, turn around time, and man power.


BARGE CARRIERS


Barge carriers push it to the limit when it comes to the size of the cargo in which it can carry, each container can way as much as 1,000 tons a piece. Barges though build similar to containerships have two methods in which it can be loaded. One method is the LASH system which stands for lighter aboard ship. In this system the loaded barges are lifted over the stern by a gantry crane hooking the floating barge. Once the barge is clear of the deck the gantry crane runs it to its position where it will be secured for sea. The second method is the Seabee it works off the same principle as the LASH method except that instead of cranes the Seabee uses a submergible platform and uses it as an elevator to hoist cargo. This system can carry a substantially larger load then the LASH system


ROLL-ON/ROLL-OFF


Often referred to as RO-RO’s, these ships are used for cargo on wheels that is driven aboard using special ramps that the ship itself carries. RO-RO’s generally have many decks that are all very short in an effort to load as much cargo as possible on to the ship since there can only be one layer of cargo per deck. The RO-RO requires very large openings in the transverse bulkhead in order to operate correctly and efficiently. These doors must be watertight and gasket sealed in order to assure that water cant get into the ship while it is underway. Also a substantial ventilation system must be put in to ward off and vent out any of the toxic fumes that the cars give off.


CRUDE OIL TANKERS


Crude oil tankers have three different classifications, they are your standard crude carrier, VLCC (very large crude carrier), and ULCC (ultra large crude carrier). The cargo spaces on these tankers are divided into three tanks athwart ships which