The article analyzes the current state of the low-speed marine engines (LSME) market. The main requirements for marine engines put forward by the International Maritime Organization (IMO) in terms of energy efficiency and emissions of harmful substances are given. Further ways of improving LSMEs in terms of reducing CO2 emissions by switching to carbon-free marine fuel — ammonia — are briefly considered. It is shown that in the absence of the possibility of acquiring a license for the production of such engines, the organization of our own LSME production in Russia within a reasonable time frame is unlikely. A brief overview of the design and history of development of free-piston engines and their use on ships as LSMEs is given. The possibility of replacing LSMEs of a classical design with free-piston engines is shown, taking into account modern requirements for environmental friendliness and efficiency of marine engines. Information is given on the progress of work on a project demonstrating the capabilities of free-piston engines as LSMEs.

   The author's task is to draw attention to a way of developing domestic marine engine-building based on free-piston technology as an alternative to traditional LSME.