Sea transportation is the movement of goods and people from one place to another by sea or any other waterways. Hence, ship engineers, as it were, are people who run or in charge of the engine in a ship. They play major roles in ensuring a smooth sea transportation and preventing unwanted mechanical or technical faults by maintaining propulsion plants during operations. These, among others, explain indispensable obligations of ship engineers.
In addition, ship engineers also perform other functions such as maintaining the sewage, the lighting, the heating, the air conditioning, the lubrication, the ventilation, the propeller shafts and propellers, the refrigeration, the fabrication of engine parts for replacement e.g. bolts, valves etc., installing the engine controls, the electrical power generation plant as well as the water system in the ship.
Other duties include managing life-saving equipment, fuel management, boat management, safety management, fire-fighting, first aid, supervising loading and off-loading hazardous materials, monitoring working conditions of engines and any other equipment so as to know whether or not they are working properly and to  identify any fault, as well as engaging in pollution prevention in line with the international regulations and nautical tasks.
However, there are different positions in ship engineering division generally for
British and US vessel. Here are the positions:
1. Chief Engineer: This post is in charge of engine department.
2. Second Engineer in US it’s called 1st Assistant Engineer: This post engages in daily operations of engine department.
3. Third Engineer in US it’s called 2nd Assistant Engineer: The position takes the responsibility of maintaining the auxiliary engines and boilers.
4. Fourth Engineer in Us it’s called 3rd Assistant Engineer: This engineer unit maintains the air compressors, purifiers, pumps and auxiliary machinery.
5. Electro-technical Officer (ETO): The officer in charge maintains electrical and electronics equipment like radars, VHF and so on.
6. Electrical Officer: The officer maintains only the electronics equipment.
7. Junior Engineer
8. Cadet

Technicians and craftsmen in ship engineer division
In ship engineer division, there are other regular skilled jobs which include:
a. Machinist or fitter: The person in charge fabricates and repairs machines.
b. Motorman: The person assists the engineer and also does menial jobs.
c. Oiler: The duty is to ensure that the machines are well lubricated.
d. Wiper: The duty is to keep the engine room clean and tidy.
Having considered the above enormous tasks of ship engineer division, it won’t be too much to say that the engineer division is indispensable in marine transportation.

Greatest volume of cargo in international trade is carried by sea transportation. This explains one of the important roles sea transportation plays in the world. Freight transportation by sea is a cheaper means by which people move their cargoes in large quantity from one nation to another. Industrial revolution becomes  effective in a nation that has a well-developed marine transport. Indeed,
it’s a necessary complement to other modes of freight transportation and trading
activities.
However, ships can be classified by its propulsion and size. Below are the types of
ships in marine transportation:

1. Bulk Carriers: Like the name suggests, they are cargo ships used to carry large number of cargo. The main surface of the out-side floor of the ship is designed like a large box to carry cargoes.

2. Container Ships: Like the name suggests, it is used to carry large dry cargoes packaged into large standardized containers. To a large extent, most of these ships are moved by diesel engines.

3. Tankers: They are designed to carry liquid materials such as petroleum gas, crude oil, petroleum products, liquefied petroleum gas (LPG), liquefied natural gas (LNG), chemicals, vegetable oil, wine and so on.

4. Refrigerated Ships: These are also cargo ships used to carry perishable items that need controlled temperature to preserve its freshness and such perishable items include: fruits, meat, fish, and vegetable among others.

5. Roll-on/roll- off ships: These ships are specially designed to carry dry cargoes like automobiles, trailers, railway carriages. The ships are designed with ramps that make it easy to roll in and roll out.

6. Coastal Trading Vessels: These are used for trading activities between different areas, nations and continents. They are usually small in size.

7. Ferries: These kinds of vessels are commonly used as public transport for people living in water-side areas; they are used to move passengers and their belongings such as any form of vehicles, luggage, and equipment, among others.

8. Cruise Ships: These are used mostly by tourism industries. They are ships used purposely for pleasure and people traveling in cruise ships are people traveling for recreation.

9. Ocean Liners: These are ships used to carry large number of people from one seaport to another on a long regular- distance planned at a certain time. They are also used to carry cargoes, mails and at times, they are used for any other purpose. Ocean liners normally are strong ships designed to resist rigorous conditions they are likely to face while on ocean.

10. Cable Layers: These are undersea or submarine built vessels purposely used to lay cables for telecommunications, electricity etc. below the surface of water.

11. Tug-boats: These boats are used to tow other boats or vessels.

12. Dredgers: They are ships usually used in a depth-less area of the sea that may affect smooth operations of the ship. These ships are designed to dig out and remove the materials that sink to the bottom of the sea.

13. Barges: They are flat-bottom boats usually used to move heavy cargoes on rivers and canals. It is important to note that most barges use tugboats or towboats to operate.

14. Multi-purpose ships: They are ships used to carry various items both in bulk and small quantities and at times, they are used to move heavy items. The modern ones are now designed to carry containers.