Development of the Imperial Japanese Navy Battle Cruiser (Part 10)

The vessel with insufficient stability has improved by withdrawal of some arms, or adoption of fixed ballast. 'Mogami' is - which equipped with the bulge and increased stable ability.

However,at the end of the same year, the fleet of the navy under training encountered the typhoon.
But, the fleet plunged into the typhoon without taking refuge.
And the accident occurred which cuts the bow of a destroyer.
Moreover, in other destroyers and battle cruisers - which wrinkles generated to the deck.

The battle cruiser 'Nachi' was observing the weather at this time.
That, the wind velocity of a typhoon is 35m per second.
Wavelength is 150m.
Wave height was 10m to 12m.

The ratio of (wavelength / wave height)is 10.
This is a numerical value which is not believed.

The common sense of the shipbuilding community
in the world of those days was setting the limit value of(wavelength/wave height)to 20. Hull is designed ( for this as a ultimate value).

However, the adjacent seas in Japan were the severe conditions exceeding ultimate value. The navy kept to secret this accident .

And the improvement of the thorough hull intensity of a battle cruiser and a destroyer was given.

* Weather conditions which are not believed generate the adjacent seas in Japan of winter.

The Showa50s(the1975s),
Three Japanese Panamax type ore ships(Dwt:70,000t to50,000 tons)caused the cutting accident of a bow in the sea of stormy weather.
(As for the crew member, all were rescued.)

Although the hull had floated for several days, and sank.

Moreover, 2 vessels of the foreign ship cut the bow and also sank in an instant. All crew members of 2 ships are missing.)
In any case, they were the usual weather conditions of winter.*

The warship with insufficient hull intensity,
1: The hull of welding structure with a bow and a stern, dissolve the hull above the water line and reinforces.
2: The ship which used welding for the hull central part gives reinforcement for stopping the stress of sagging of a-hull-to20%.

The shipbuilding community in the world did not get interested in OG of a hull until now.. However, after this, it came to get interested in the numerical value of OG of a hull.

These improvement reconstruction was secretly carried out. so that it might not be known by the foreign navy.
For this reconstructions, construction of new style battle cruiser'Tone' was long overdue.

Completion became the anticipation in Showa12. A disarmament treaty is a year end in Showa11.

Then, the main guns of 'Tone' were changed from15.5cm to20cm.

Construction of 'Tone' class remained in 2 ships.
And the battle cruiser of the last of the imperial navy,they are 2 ships of 'Suzuya' and 'Ibuki'..

'Ibuki' is converted into an aircraft carrier by construction halfway.

(End)