IJN Satsuma (SD-1910 (1929-mod))


Return to Japanese Navy page:


The Satsuma and Aki were supposed to be Japans first all big gun battleships laid down in 1905 they would have pre-dated the Dreadnought. But because the Russo-Japanese war had very nearly bankrupted Japan the two ships could only have one pair of 12" fore and aft the remaining guns were six twin 10" disposed equally on each broadside. Aki was altered during construction to take the first turbine propulsion system fitted to a Japanese Navy battleship, this gave the Aki a slightly different silhouette as the Aki required a 3rd funnel. On completion the ships were classed as semi-dreadnoughts.

None of the Japanese ships had much to do in WW1 and the state of the ships at the end of WW1 was excellent. However the Japanese took the slights of the Washington Treaty where they felt the Western Allies were out to cripple their Navy quite personally as so many of their ships would have to be compromised to comply with the Washington Treaty. At this point the Japanese high command took the step to actively circumvent the terms of the Treaty wherever possible and to stockpile weapons for a time when the Japanese would say "No" to further Treaty restrictions. The twelve 10" twin turrets and handling equipment would eventually arm three large cruisers of the Tsushima Class.

The Satsuma and Aki were both to be discarded/scrapped/sold under the Treaty, but through the loophole of 'Training Ships" where Capital Ships had been demilitarised to be kept on as training ships, both were given a reprieve along with the other battleships and large armoured cruisers over 10,000 tons. At first the two ships just had the 10" guns removed and boilers were disconnected to reduce the power output significantly. In 1925 they were taken in hand for conversion to cruiser training ships where the ships would be altered to resemble the latest Takao class cruisers. The superstructures from A to Y turret were removed and replaced. While this was underway the chance was taken to remove the old engines from both ships and replace them with units from the cancelled battlecruisers and battleships of the 8x8 plan. This increased the original speed from 18-20 knots to 24 knots and was a direct contravention of the Treaty, the Japanese did not report these sort of things. What the West did not know would not hurt them...... just yet. Arms and armament were continued to be added, twin 5" replaced the single 4.7" AA guns and eventually up to 54 of the 25mm guns were fitted for extra AA protection.

In their new guise the ships were to be used to escort the troop landing convoys and provide them with AA and large gun support against surface or air interception, while once on station the main guns could be used as direct shore support artillery. This freed up the main battle fleet units to be just that, the main battle fleet, and not be sidetracked into ancillary duties.

March 2021. The bridge structures used on my original drawing above were from a much later cruiser class. "Taken in hand 1925" would put the drawings in the Furutaka class timeframe. I will try another drawing utilising a Furutaka type bridge and superstructure and see how that looks in comparison.


Displacement 19,800 tons std, 24,250 tons full load
Length 491 ft
Breadth 84 ft
Draught 27.5 ft
Machinery 2 shaft Steam turbines, 45,000shp
Speed 24 knots
Range 3,500 miles at 18 knots
Armour 9" side, 3" deck, 9.5"-7" turrets.
Armament 1st try - Satsuma

4 x 12" (2x2)

16 x 5" (8x2)

36 x 25mm (12x3)

2nd try - Aki

4 x 12" (2x2)

8 x 5" (4x2)

16 x 25mm (8x2)

Aircraft nil
Torpedoes nil
Complement 940
Notes IJN Satsuma (1905-1909)

IJN Aki (1906-1911)


Aki underway during WW1. The three funnel arrangement necessitated by the turbines is visible.


Return to Japanese Navy page: