Type F submarine

The Type F submarines (F型潜水艦, F-gata Sensuikan) were medium Imperial Japanese Navy submarines in commission during the 1920s. They were Japan's first true seagoing submarines and the earliest Japanese submarines classified as "second-class" or "medium" submarines.

Class overview
Name: Type F submarines
Builders: Kawaski, Kōbe, Japan
Operators:  Imperial Japanese Navy
Preceded by: None
Succeeded by: Type L submarine
Subclasses:
  • Type F1 (Ro-1-class)
  • Type F2 (Ro-3-class)
Built: 1917–1922
In commission: 1920-1932
Completed: 5
Retired: 5

Design and description

The Type F submarines were designed by the Italian firm Fiat-Laurenti and built under license by Kawasaki-at Kobe, Japan.[1] The Type F submarines were the Imperial Japanese Navy′s first true seagoing submarines,[1] and when the Japanese adopted a three-tiered classification system of its submarines as first-class (I), second-class or medium (Ro), and third-class (Ha) on 1 November 1924,[2] the Type F submarines were the earliest to receive the second-class classification,[1] as reflected in their low numbers in the Ro series,[1] and in fact they were the earliest Japanese submarine classified as anything higher than third-class.

As built, Type F submarines had no deck gun, but soon after they were completed each of them had a 76.2 mm (3 in)/40 gun installed on her deck.[1] The Type F submarines had non-cylindrical hulls intended to provide extra internal space, but the Japanese considered the hulls weak despite the provision of additional scantlings during construction to reinforce them.[1] Because of their disappointing performance, they did not serve as the basis for any later Japanese submarine classes.[1]

Class variants

The Type F submarines were divided into two subclasses:

  • Type F1 (F1型(呂一型, Ro-ichi-gata, Ro-1-class)
  • Type F2 (F2型(呂三型, Ro-san-gata, Ro-3-class)

Type F1 (Ro-1-class)

Submarine No. 18 (left background) and Submarine No. 21 (foreground) in 1920. On 1 November 1924, they were renamed Ro-1 and Ro-2, respectively.

The F1 subclass was ordered under the 1915–1916 naval program.[1] Two were constructed between 1917 and 1920:[1][3][4]

Name Laid down Launched Completed Notes, fate
Ro-1
ex-Submarine No. 18
5 January 1917 28 July 1919 31 March 1920 Renamed Ro-1 on 1 November 1924. Stricken 1 April 1932.
Ro-2
ex-Submarine No. 21
1 July 1918 22 November 1919 20 April 1920 Renamed Ro-2 on 1 November 1924. Stricken 1 April 1932.

Type F2 (Ro-3-class)

Submarine No. 33 at Sasebo, Japan, ca. 1922. She was renamed Ro-5 on 1 November 1924.

The F2 subclass (Ro-3-class) was ordered in 1918.[1] It was an improved version of the F1 subclass with a modified bridge.[1] The Fiat diesel engines were unreliable and the F2 subclass′s top surface speed of 14 knots (26 km/h; 16 mph) was well below the intended 17 knots (31 km/h; 20 mph).[1] Additional F2 subclass units planned under the 1919 construction program were cancelled and replaced by the new Kaichū-type and Type L submarines.[1]

Three submarines of the F2 subclass were constructed between 1919 and 1922:[1][5][6][7]

Name Laid down Launched Completed Notes, fate
Ro-3
ex-Submarine No. 31
28 October 1919 10 March 1921 15 July 1922 Renamed Ro-3 1 November 1924. Stricken 1 April 1932.
Ro-4
ex-Submarine No. 32
22 December 1919 22 June 1921 5 May 1922 Renamed Ro-4 1 November 1924. Stricken and hulked 1 April 1932.
Ro-5
ex-Submarine No. 33
1 March 1920 17 September 1921 9 March 1922 Renamed Ro-5 1 November 1924. Stricken and hulked 1 April 1932.

Characteristics

Sources[1][8]

Type F1 (Ro-1) F2 (Ro-3)
Displacement Surfaced 689 long tons (700 t) 689 long tons (700 t)
Submerged 1,047 long tons (1,064 t) 1,047 long tons (1,064 t)
Length (overall) 65.6 m (215 ft 3 in) 60.5 m (198 ft 6 in)
Beam 6.1 m (20 ft 0 in) 6.1 m (20 ft 0 in)
Draft 4.2 m (13 ft 9 in) 4.1 m (13 ft 5 in)
Power plant and shaft 2 × Fiat diesel engines
2 x Savigliano electric motors
2 shafts
2 × Fiat diesel engines
2 x Savigliano electric motors
2 shafts
Power Surfaced 2,800 bhp (2,100 kW) 2,600 bhp (1,900 kW)
Submerged 1,200 shp (890 kW) 1,200 shp (890 kW)
Speed Surfaced 13 kn (24 km/h; 15 mph) 14 kn (26 km/h; 16 mph)
Submerged 8 kn (15 km/h; 9.2 mph) 8 kn (15 km/h; 9.2 mph)
Range Surfaced 3,500 nmi (6,500 km)
at 10 kn (19 km/h; 12 mph)
3,500 nmi (6,500 km)
at 10 kn (19 km/h; 12 mph)
Submerged 75 nmi (139 km)
at 4 kn (7.4 km/h; 4.6 mph)
75 nmi (139 km)
at 4 kn (7.4 km/h; 4.6 mph)
Test depth 40 m (130 ft) 40 m (130 ft)
Fuel 58.4 tons 58.4 tons
Complement 43 43
Armament As built:
• 5 × 450 mm (18 in) torpedo tubes
(3 × bow, 2 × stern)
• 8 × Type 44 torpedoes
• 1 × 7.7 mm machine gun
Added after completion:
• 1 x 76.2 mm (3 in) deck gun
• 5 × 450 mm (18 in) torpedo tubes
(3 × bow, 2 × stern)
• 8 × Type 44 torpedoes
• 1 × 7.7 mm machine gun
Added after completion:
• 1 x 76.2 mm (3 in) deck gun

References

  1. Gray, p. 247.
  2. Gray, p. 245.
  3. "RO-1 ex No-18". iijnsubsite.info. 2017. Retrieved 22 October 2020.
  4. "RO-2 ex No-21". iijnsubsite.info. 2017. Retrieved 22 October 2020.
  5. "RO-3 ex No-31". iijnsubsite.info. 2017. Retrieved 22 October 2020.
  6. "RO-4 ex No-32". iijnsubsite.info. 2017. Retrieved 22 October 2020.
  7. "RO-5 ex No-33". iijnsubsite.info. 2017. Retrieved 22 October 2020.
  8. navypedia.org "Fiat" 2 class submarines (18-GO) (1920 - 1922) Accessed 22 October 2020

Bibliography

  • Gray, Randal, ed., Conway′s All the World′s Fighting Ships 1906–1921, Annapolis, Maryland: Naval Institute Press, 1985, ISBN 0 87021 907 3.
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