IJN RO-35 & RO-36

K7 Type

As seen in 1943

Pit Road no.W45

Scale 1:700 Water Line Series

Click on the pictures to enlarge.



2 3 4


6 7 8





RO-35 & RO-36

KG Type

The Kaichu type submarines were double-hulled medium sized submarines of the Imperial Japanese Navy during World War II. They were derived from the Kaigun-shiki Tyuugata  submarine (KT).

These ships were based closely on the K5 class. As almost the entire force of RO submarines was obsolete by 1940, this class was an attempt to fill the shortage of medium submarines. The first of the class was laid down in October 1941; ten were completed in 1943, with the final eight finished in 1944. The increase in size from the K5 translated into greater range as more fuel could be carried. Additionally, more powerful diesel engines were fitted and the submarine's operating depth was improved. These were the last RO boats built. Many other projected units in this class were canceled after they proved alarmingly vulnerable to US antisubmarine forces.

Armament: Four 21-in. bow torpedo tubes and ten torpedoes; no guns were originally planned, but during construction a 3-in. deck gun and a twin 25mm cannon were added. These were the first RO boats capable of firing the Type 95 torpedo.

War service: The K6 class epitomized the wartime failure of the Imperial Navy's submarine force. Despite being well designed and fairly maneuverable and generally considered to be among the best of Japanese submarine designs, all but one (RO-50) were destroyed by war's end. Of these, 13 were sunk by surface ships, two by air attack (one by an acoustic torpedo) and two went missing. In exchange, the K6 boats succeeded in sinking a single destroyer escort, an 800-ton (726-tonne) yard oiler, and possibly a tank landing ship while damaging an attack transport. Most of the units in this class never even reported attacking the enemy, an utter condemnation of the over-cautious nature of their skippers. Their dismal record showed the futility of sending submarines to attack US fleet forces and the unsuitability of using submarines to defend islands against amphibious attack.

K7 Type:

  • RO-35
  • RO-36
  • RO-37
  • RO-38
  • RO-39
  • RO-40
  • RO-41
  • RO-42
  • RO-43
  • RO-44
  • RO-45
  • RO-46
  • RO-47
  • RO-48
  • RO-49
  • RO-50
  • RO-55
  • RO-56






Mitsubishi, Kobe

Mitsubishi, Kobe

Laid down

1941.Oct. 9

1942. Mar. 7


1942. Jun. 4



1943. Mar.25

1943. May.27


1943. Aug. 25 sunk (action, near Espiritu Santo)
[12.57S, 164.23E]

1944. Jun.13 sunk
(action, E of Saipan)
[15.21N, 147E]

Technical specification:

Displacement 960t standard, 1115t surface, 1447t submerged
Length 76.50m pp, 79.00m wl, 80.50m oa
Width 7.05m
Draught 4.07m
Machinery 2-shaft diesel and electric motor, 4200bhp surface, 1200shp submerged
Speed 19.7kt surface, 8kt submerged
Armament 4-53cm TT, with a total of 10 torpedoes carried 1-8cm/40cal AA gun, 2-25mm AA
Complement 54


Building the model of RO-35 & RO-36:

The building of the model kit was mostly straight forward, as the quality of the Pit Road models is high. I used the PE-set's from Tom's model Work's and IJN crew from Eduard (the box contains 2 submarines as well as 2 mini subs. Please see the warship main site) The most challenged and also rewarding phase was the weathering of the hulls.

The scratch building on the kit is: 

Collapsible mainmast on the foredeck  (0.3mm) silver wire. Rigging made by invisible tread painted with very thin layer of grey. The "balls" on the wires is added with thicker layers of paint (radio wire and insulators). The twin 25mm AA guns is from the kit too, but their mounts were sanded down to a narrower beam and two seats were added (made from 0.5mm wire).

This was a enjoyable model kit to assemble. I was pleased with the choice of adding a full hull option to the waterline kit, and the pictures show, you will have more display and photo opportunities with the kit. The last two pictures of the models are the background painted in Photo Shop to show the units underwater.


Books form my own library :  

Japanese Naval Warship Photo Album Submarines and depot ships

from Diamond Sha books.  


Submarines of the Imperial Japanese Navy 1904-1945 from Conway Maritime press

(Pictures and history)


Imperial Japanese Navy  Submarines 1941-45 from Osprey publishing

(Pictures and history)

The building time was 4 days. 

Mar. 2009

If you have any questions, remarks or things you will share, please don't hesitate to contact me.



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