Stone Below, Slag Brick Above
The Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room (旧佐世保海軍工廠川棚魚雷遠距離発射場機械室及び水雷調整室) is a torpedo preparation building erected around 1918 on Katashima in Kawatana, Nagasaki Prefecture, and enlarged in 1939; it was registered as a Registered Tangible Cultural Property of Japan on August 15, 2024. It faces the jetty head-on, about 12 meters across the front and 27 meters deep, a single-story stone and brick structure with a building area of 330 square meters.
A dividing wall splits it into two rooms. When new, the west room was the torpedo adjustment room and the east room the machine room. Here torpedoes waited before firing while crews loaded fuel and oxidizer and tuned them, before sending them down the rails to the launch platform.
In the expansion of 1939 the building was converted into an air compressor house, presumably producing the compressed air that drove the torpedoes, and its walls were raised to their present height. Today the roof is gone and only the shell of walls remains.
Two Eras in One Wall
The thing to notice at the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room is that its walls change material, and century, partway up. The lower section dates from 1918: stone, 4.5 meters high. Outside, the builders used Hario stone, a tuff quarried near Urago on the Hario peninsula, left with a rough split face. The mortar joints are still tight.
Inside, the walls switch to sandstone, dressed and laid in level courses with fitted joints, then coated with mortar. Different stone, different bond, inside and out.
The upper section is the 1939 addition, built of slag brick to lift the walls to 6.8 meters. These bricks were made from blast-furnace slag shipped from the steelworks of northern Kyushu, and the Sasebo Naval Arsenal used them from 1928 to 1943. Darker brick riding on pale split stone shows both periods at a glance.
Why It Matters
The Agency for Cultural Affairs values the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room as a military remain important for both its function and its construction. According to Kawatana's preservation plan, no other building in the Sasebo Naval Arsenal combines a stone base with a slag-brick addition like this.
The rough stone finish closely resembles the telegraph office at the Hario Radio Transmitting Station in Sasebo, completed in 1922. Same stone, same working method. This building went up four years earlier, suggesting the naval district's engineers were already sharing a common design approach.
It is the largest structure on the island, called the headquarters building in the town's guide materials. Every torpedo tested here passed through it before and after firing, which makes it the hinge of the whole range.
Viewing the Building
In 2024 concrete spalled from the frame over the doorway of the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room, and the building has since been fenced off. It will stay closed until repairs are finished, after which the town will decide on access.
You can still study the exterior from outside the fence. The southwest face, the angle chosen for the national database's main photograph, shows the seam between Hario stone and slag brick most clearly. From the landward end of the jetty, you can also see how this building, the jetty and the offshore platform line up on a single axis.
Graffiti has damaged parts of the walls, and the town plans to restore them. Please do not touch or mark the stone. Directions to Katashima Park and general visiting information are gathered on the page for the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range as a whole.
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Q&A
- Can you go inside the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room?
- Not at present. Concrete spalled from the doorway in 2024, and the building is fenced off until repairs are complete.
- What was the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room used for?
- Torpedoes were stored, fueled, charged with oxidizer and adjusted here before firing. In 1939 it was converted into an air compressor house.
- Why do the walls of the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room look different at the top?
- The lower walls are Hario stone from 1918, while the upper walls are slag brick added in 1939 to raise the building's height.
- What stone was used for the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room?
- The outer walls are Hario stone, a tuff quarried near Urago, left with a split face. The inner walls are sandstone laid in level courses and coated with mortar.
- When was the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room registered as a cultural property?
- On August 15, 2024, together with the firing platform, jetty, oil storehouse and observation post.
Basic Information
| Name | Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room |
|---|---|
| Location | 151-1 Katashima, Mitsukoshi-go, Kawatana-cho, Higashisonogi-gun, Nagasaki Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2024/8/15 (Reiwa 6) |
| Quantity | 1 building |
| Dimensions | Stone and brick, single story, building area 330 square meters |
| Owner | Kawatana Town |
| Public Access | Inside Katashima Park; exterior viewable from outside the fence, free. Interior closed |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Machine Room and Torpedo Adjustment Room
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00015108
- Kawatana Town: Preservation and Use Plan for the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range (Japanese)
- https://www.kawatana.jp/cat03/c3-03/post_732/index.html
- Kawatana Town Tourism Guide: Torpedo Launch Test Site (Japanese)
- https://www.kawatana.jp/kankou/2010/12/post-24.html
Last verified: 2026.09.25
