Machinist's mate (or MM) is a rating in the United States Navy's engineering community. Description According to the Bureau of Naval Personnel (BUPERS), the job of a Machinist's Mate is to "operate, maintain, and repair (organizational and intermediate level) ship propulsion machinery, auxiliary equipment, and outside machinery, such as: steering engine, hoisting machinery, food preparation equipment, refrigeration and air conditioning equipment, windlasses, elevators, and laundry equipment. Operate and maintain (organizational and Intermediate level) marine boilers, pumps, forced draft blowers, and heat exchangers; perform tests, transfers, and inventory of lubricating oils, fuels, and water. Maintain records and reports, and may perform duties in the generation and stowage of industrial gases." Enlistees are taught the fundamentals of this rating through on-the-job training or formal Navy schooling. Advanced technical and operational training is available in this rating during later stages of career development. Machinist's Mates (submarine) and Machinist's Mate (surface) generally fall into one of three roles: Propulsion mechanics The core job of a Machinist's Mate is the engine room. A mechanic's job in the engine room is to operate the steam plant that provides propulsion, electric power (along with Electrician's Mates), potable water, and service steam to the ship. Machinist's Mates operate the boilers that generate the steam and use it to operate main engine (propulsion turbines), turbo generators, distilling units, and various auxiliary turbines. This job was previously performed by Boiler Technicians, however, the BT rating merged with Machinist's Mate in 1997. Machinist's Mates working in the propulsion plants are often referred to as "pit snipes", "hole snipes", or just "snipes" for short. Machinist's Mates responsible for the propulsion plant are found in machinery division (or main engine division, main propulsion division, etc. in some ships), commonly referred to simply as M-Division or MP-Division. On surface nuclear ships, propulsion mechanics are found in Reactor Propulsion Division (commonly still referred to as M-Div), Reactor Mechanical (RM) Division, or Reactor Laboratories (RL) Division. was the exception, in that M-Division was still part of Engineering Department, as opposed to Reactor Department. Navy Times of 7 January 2013 reports the Navy will be realigning Machinist's Mate, and Engineman ratings. EN whose primary skills are in maintaining auxiliary engineering will become MMs. EN aboard ship will now concentrate strictly on diesel propulsion which powers many amphibious ships, while all surface shipboard auxiliary machinery work will be under the MM rating. This will affect almost 2000 ENs.