A table summarizing the specifications of each of the three fortresses
article |
No.1 Sea Fort |
No.2 Sea Fort |
No.3 Sea Fort |
|
Artificial island |
Start date |
Meiji 14 (1881) Aug. |
Meiji 22 ( 1889 ) July |
Meiji 25 |
Completion date |
Meiji 20 (1887) June |
Meiji 32 (1899 ) June |
Meiji 40 (1907) Oct. |
|
Upper structure |
Start date of construction |
Unknown |
Meiji 33 (1900) 16th March |
Taisho 3 (1914) Sept. and after |
Completion date |
Meiji 23 (1890) Dec. |
Taisho 3 (1914) June |
Taisho 10 (1921) March |
|
Construction time |
9 years | 25 years | 29 years | |
Construction site |
in the sea at the tip |
2,577m west |
611m south of No.2 Sea Fort 2,589m north of
|
|
Armament[ note1] |
two 12cm cannon four 12cm cannon one 19cm cannon fourteen 28cm howitzers |
two 27cm cannon four 27cm cannon eight 15cm cannon |
eight 10cm cannons four 15cm cannons |
|
Water depth |
Deepest depth 4m60cm Shallowest depth 1m20cm |
Deepest depth 12m Shallowest depth 8m |
Deepest depth 39m |
|
Geological structure of the seabed |
Sands mixed with |
Sands mixed with |
Sands mixed with gravels |
|
Speed of tidal current |
1m | 1.2m | 1.5m | |
Difference between high and low tide |
2m | 2.2m | 2.2m | |
Area of upper foundation |
23,000 m² | 41,000 m² | 26,000 m² | |
Construction cost |
378322 yen |
91,647 yen |
24,93,697yen |
[ note 1 ] Initial armament : Although armament was strongly influenced and changed by the background of military diplomacy and advance of weapons and changes of strategy, initial construction armaments of each sea fort were enumerated here.
[ note 2] Cost converted into today’s yen : Those 3 forts construction costs were estimated based on the cost of Meiji 14 (1881) as a basement of one and multiplied by the deflator of 4.638 of Heisei 30 (2020).