Fleet And Ports Operation. In fact, the organization of the "Temporary Course" marks the beginning of the historical development of the educational structures training navigational specialists in this country. The course trained officers, graduates of the Military School in Sofia, to acquire naval qualifications, as well as Bulgarian graduates of foreign naval schools who for some reason did not manage to graduate abroad. The participants in the Temporary Officer Course passed and exam and were awarded the qualifications of naval officers. At the turn of the 20th century, the Sub-officer Maritime School made a new step forward. In 1900 it was headed by lieutenant Todor Solarov. It was during his time in office that the institution was moved to the city of Varna and renamed Engineering School to the Fleet. Todor Solarov justified the need for more thorough training of its graduates, as a result of which in 1904, with an act of the National Parliament, it became the first technical secondary school in the country and the duration of training was extended to six years. In 1906 the school issued the first matriculation certificates. In 1910, the first building specially designed and erected for the needs of the Engineering School to His Majesty's Fleet was built in Varna. The unit which remained in Ruse was renamed Miner and Stoker School (Miner school with stoker training) with duration of training of four years, including practical training, with the first two-year of training recognized as compulsory military service for the students. The Miner and Stoker School was temporarily closed down in 1909. In 1912, due to the fleet's increased need of technical specialists, it was reopened under the name Maritime Special Schools, which in turn were subordinate to the newly formed structure in Varna called Training Unit (later renamed Maritime Training Unit). The schools were established in 1912. In 1913 they admitted the first class of 34 cadets. Originally, the Maritime Special Schools consisted of three units: mining and electrical engineering, stoker and steersman. During World War I, the Diver School and Radiotelegraphy School were formed and briefly functioned. The duration of training in the schools was four years. They can be seen as the prototype of the present-day Postgraduate Studies Department and Professional Sergeant College within the Nikola Vaptsarov Naval Academy. By 1912, the Training Unit included not only the Special Schools, but also the Engineering School to His Majesty's