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|Other names||Third assistant engineer|
|Reports to||Chief engineer, second engineer, third engineer|
|Licensed||Yes Merchant Mariner Credential|
|Duties||daily maintenance and operation in the engine department|
|Requirements||completed 4 year course at academy or complete exams as unlicensed engineer with required sea time|
|Watchstander||Depends on manned/unmanned engine room, may be called in to do security watches when in port|
|Watch (at sea)||engine room on board ships (2000-0000, 0000-0400, 0400-0800, 0800-1200, 1200-1600, 1600-1800, 1800-2000)|
|Watch (in port)||engine room, security checkpoint (1600-2400)|
A Third Assistant Engineer’s License is earned through the U.S.C.G or other regulatory body (such as the MCA in the UK) that allows the recipient to work onboard any vessel up to the rank of a fourth engineer or below. It is earned by those who have completed the necessary STCW requirements to obtain it. Third Assistant Engineers work on board ships and do most of the general labor among the officers, as well as leading the oilers and other engine room crew. Depending on the style of ship, company, and other factors, they are called "the Third" or "the Fourth" and usually stands a watch and sometimes assists the third mate in maintaining proper operation of the lifeboats. This credential, along with complimentary endorsements and recognitions such as for tankers and cargo ships, is earned by cadets who complete the Marine Engineering Technology (MET) or Mechanical Engineering license track (ME(L)) majors at any of the credentialed maritime academies. In the US, these academies include California Maritime Academy , Great Lakes Maritime Academy, Massachusetts Maritime Academy, Maine Maritime Academy, State University of New York Maritime college, and Texas A&M Maritime Academy. 
American 3rd Assistant Engineers can receive an optional commission as ensign in the U.S. Naval Reserve, Merchant Marine Reserve, or Coast Guard Reserve. With experience and additional training, third officers may qualify for higher rank.
The general duties for a third assistant engineer (fourth engineer) differ from ship to ship. Generally speaking, third assistant engineer (fourth engineer) are tasked with controlling the main propulsion systems, water systems, and anything else tasked to them from up in the chain of command. A third assistant engineer (fourth engineer) is part of the engine company’s chain of command. The top of this chain of command is the Chief engineer (first engineer) who is in command of engine room and auxiliary areas that would relate. Then comes the first assistant engineer (second engineer), second assistant engineer (third engineer), and then the third assistant engineer (fourth engineer). These are the officers within the engine company of a standard ship.
The third assistant engineer is in charge of keeping the plant in operation, with command being passed down and being delegated by who is on watch. There main duties include those involving propulsion, sewage processing and treatment, electrical, and general maintenance. However, they are trained to be competent in a wide variety of fields such as HVAC (heating, ventilation, and air conditioning), electronics, Shipboard medical and the operation of both steam and diesel driven plants. Duties will vary from ship to ship, but the Fourth Engineer is expected to handle jobs in all areas of the ship, as they are needed. In some instances, especially in the case of an emergency, third assistant engineers are tasked with using relevant knowledge to save the ship and her crew. Some examples of this include fixing pumps, monitoring equipment, and being trained in all safety procedures.
The rank of third assistant engineer can be earn by one of two ways, either through school or working your way up as another member of the engine room crew. Both ways require the individual to complete specific courses as well as meet the requirements set out by STCW (Standards of Training, Certification and Watch keeping for Seafarers).  Some such courses that are required no matter which method a potential seafarer chooses are the lifeboatman’s safety course and exam, Ship security and responsibility (SSAR), and Marine firefighting. These courses are required of crew members as they are important to the safety of the vessel and her crew, especially in the case of an emergency. All United States Merchant Marine must adhere to the strict compliance of international maritime organization's regulations in regard to safety and environmental regulations on shipping. Many of these same requirements can be found for vessels that are not protected under the United States Jones Act. In relation to this requirement, all Third Assistant Engineers, no matter which flag they sail under, must be competent in lifesaving procedures for a vast number different shipboard emergencies. These requirements, set by CFR 46, are mandatory and apply to all ships including those going domestically and internationally to adhere to these standards for all crew members, including the Third Assistant Engineer. the International Convention for the Safety of Life At Sea (SOLAS) is the global institution responsible for mandating standards for lifesaving procedures and equipment for all maritime vessels. they have practical training for surviving in a man overboard, fire, or other emergency situation. these trainings are done at certified institutions such at the MEBA or one of the many maritime academies.
The Jones Act
the Jones Act is a federal law that was created to protected american maritime shipping interest. Simply put, the law made sure that american flagged vessels must be starting and ending their voyage in an american port. additionally, it must be manned by at least 75% american crew. this is important for american 3rd Assistant Engineers as they are directly protected by this law. 
Unions and organizations
for U.S. maritime licensed and non-licensed crew, they are mandated to be part of one of many of the unions. the maritime industry is a closed shop style of union. there are 2 major Unions that a third assistant engineer (fourth engineer): MEBA (Marine Engineers' Beneficial Association) and AMO (American Maritime Officer). These unions protect the maritime industry by protecting the workers and amassing the billets for maritime workers to take for jobs. most of these billets run for 30, 60, or 90 days. 
Notes and references
- "Maritime Academies | MARAD". www.maritime.dot.gov. Retrieved 2019-04-29.
- Bureau of Labor Statistics (U.S.A.) (2007). "Water Transportation Occupations" (PDF). Occupational Outlook Handbook. Government Printing Office. Retrieved 2008-10-14.
- brown patterson, william (1962). red book of marine engineering.
- "SOLAS". www.solas.com. Retrieved 2019-04-30.
- "About Us | MEBA Union". www.mebaunion.org. Retrieved 2019-04-29.
- "The Jones Act". www.maritimelawcenter.com. Retrieved 2019-04-29.
- "American Maritime Officers - AMO". www.amo-union.org. Retrieved 2019-04-29.
- International Labour Organization (2000-12-05). "Ship-Engineer (Machinist)". International Hazard Datasheets on Occupation. Retrieved 2007-05-26.
- International Maritime Organization (1995) . "III: Standards Regarding the Engine Department". International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, 1978. Section A–III/1.
- Description at WomenOceanographers.org
- Job Description at WHOI
- Job Description at Human Resources and Skills Development Canada
- Job Description at Maritime Industry Authority Philippines