The Naval School consisted of the:

• Naval High School (Navy Middle School): Which educated cadets for four years.
• Naval Academy: They trained four more years. The last two years were spent on board the School Ship.

From 1909, the educational system was modified; and the Navy Academy graduates, received:

• Sea training for one year on board the school ship as a Midshipman.
• Followed by three years training in the navy in the rank of Ensign.
• Upon graduation, they assumed their duties by being promoted to Lieutenant.

Some of the Year-Four students in the Navy Academy, were training as Ship's Engineers (these were schooled at the HADDEHANE), and after this year joined the fleet as Ensign-Engineers, and were educated for three years on board the school ship as engineers. After that, they would be promoted to Lieutenant (Engineering).

The 1876-1908 rank of Second Lieutenant, was represented as one ring, and knot (which in the later/modern Turkish Navy is a TEGMEN - Ensign) [1] [2]. Post-1908 the same rank insignia is called a MUHENDIS (indicating an Ensign/2nd Lieutenant) [3]. After 1916, the Midshipman adopted new special rank insignia [4] [5].

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[1] Askeri Müze ve Kültür Sitesti Komutanligi. (1986) Osmanli askeri teskilat ve kiyafetleri: 1876-1908 [Ottoman military organization and uniforms] Yayinlari: 74.

[2] In the later/modern Turkish Navy, two ranks: (i) TEGMEN (Ensign); (ii) ASTEGMEN (Midshipman), covers the transition of Navy Officer Cadets, into Lieutenants.

[3] Tunca Orses. Necmettin Ozcelik. (2007) Dunya Savasi'nda Turk Askeri Kiyafetleri 1914-1918. Militärmuseum, Istanbul: 97; 115.

[4] A 2013 study by Kadir Turker Gecer, ‘Birinci Dunya Savasi Doneminde Turk Ordusunda Kullanilan Uniforma Ve Rutbeler [The Uniforms and Ranks of the Turkish Army During the First World War].

In the 1914-1923 period, the Ottoman Imperial Navy officers typically wore a red Fez, as well as adopting a pill-box cap or shako. This was made in both white and black top versions. Both versions had a lower back band, covered with gold-gilt tape. This was in three grades:

• Junior officer - no tape.
• Mid-level officer - thin band of gold-gilt tape.
• Senior officer - thick band of gold-gilt tape.

It was also fitted with a black leather chinstrap. The main peculiarity of the Ottoman Imperial Navy officers’ pill-box cap/shako, was the 'bump' appearing at the top, and inside from the front edge above the officer's badge.

The officer's badge, as can be seen illustrated in this picture. Various badge patterns can be seen in used between 1914-18:

Type A: Ottoman Imperial Navy officers’ badge on white top cap. In particular, this variation has a ‘dragoons’ teeth patterned edge, and the ‘open’ floral design to the wreath.

Type B: Ottoman Imperial Navy officers’ badge on white top cap.

Type C: Ottoman Imperial Navy officers’ badge on white black cap (same version as ‘A’).

According to "Dunya Savasi'nda Turk Askeri Kiyafetleri 1914-1918" by Tunca Orses and Necmettin Ozcelik, a cap tally was issued which read "Türkische Marine" or "Osmanische Türkische Marine", as the sailors were now officially in the Ottoman Imperial Navy [2].

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[1] Die Mutzenbander der Verbinde der Kaiserlichen Marine im Mittelmeer und auf dem Balkan.

[2] Tunca Orses. Necmettin Ozcelik. (2007) Dunya Savasi'nda Turk Askeri Kiyafetleri 1914-1918. Militärmuseum, Istanbul: 110.

The Ottoman imperial navy added an air service in 1915, setting up a seaplane base and naval aviation school at Yesilkoy, on the shores of the Sea of Marmara.

• Six Turkish naval officers were sent to Germany for training.
• By the end of the war, four naval seaplane squadrons were created.
• In 1917, the Ottoman imperial navy "1st Seaplane Squadron" is recorded as active, commanded by Cpt. Savmi Bey, based in Izmir.
• In addition, Turkish naval air service personnel provided support for German seaplane squadrons in the Turkish theater.

The ship's Administration (Secretary) Officer wore an officers' uniform with two silver cuff rings.

The French Émeraude class submarine, the 'Turquoise' (designated Q46) commissioned on 3 August 1908.

• Damaged by Turkish gunfire and beached on 30 October 1915.
• Re-floated, and named the 'Mustadieh Ombashi (Mustecip Ombasi)'.
• Was taken into the Turkish Navy but never recommissioned [1].
• Was crewed (total crew of 21 officers and sailors), and operated as a testing ship (see the German post card below showing it in Ottoman service).
• The conning tower was painted with a large rectangle (likely to be red), with large white Ottoman script.

It is stated this ship "saw no further surface", and in 1919, was Returned to France and scrapped [2]. 

The Turquoise/Mustadieh Ombashi (Mustecip Ombasi) remained under the Turkish flag, docked at Constantinople, and unable to find suitable parts for ongoing maintenance, the ship remained in service as a fixed battery charging station for German submarines [3].

The Constantinople flotilla (U-Halbflottille Konstantinopel), also known as the U-boats of the Mediterranean Division in Constantinople" (U-Boote der Mittelmeerdivision in Konstantinopel),  was an Imperial German Navy formation set up duringWorld War I to prosecute the U-boat campaign against Allied shipping in the Mediterranean and the Black Sea in support of Germany’s ally, the Ottoman Empire.

• Operating mostly against Russian shipping in theBlack Sea.
• Had a maximum strength of 11 U–boats , and some sorces indicate 14 U-boats served in the Constantinople Flotilla (six 6 were lost operationally).

In 1917 the force was amalgamated with the Pola Flotilla, coming under the command of the U-Boat Leader, Mediterranean (Führer der U-boote im Mittelmeer); and the unit was renamed the Constantinople Half-Flotilla (U-Halbflotille Konstantinopel [4]). In 1918, with the collapse of the Central Powers, the U-boats were scuttled, or fled to join the Pola boats in their evacuation to Germany.

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[1] John F. O'connell. (2010) Submarine Operational Effectiveness in the 20th Century: Part One (1900 - 1939), iUniverse (17 Aug): 54.

[2] Paul E. Fontenoy. (2007) Submarines: An Illustrated History of Their Impact, ABC-CLIO (1 Jan): 80.

[3] Gérard Garier. (2002) Technical and Human Odyssey Submarine France, in 'Volume 3: A test of the Great War', Marines Publishing: 150-161. 

[4] Die Mutzenbander der Verbinde der Kaiserlichen Marine im Mittelmeer und auf dem Balkan.