The Special Type 3 Ka-Chi (特三式内火艇 「カチ」) was a tank of the Imperial Japanese Navy to succeed the Ka-Mi. Based on the Army’s Chi-He tank and refined with naval ingenuity, this amphibious giant could even be transported by submarine! While its armour is relatively thin, the pontoon-equipped, submarine-like hull provides ample spaced armour, enhancing durability. Combined with a large crew complement, the Ka-Chi is surprisingly survivable. In this article, we dive into the details of this landship-turned-swimmer.
| Pros | Cons |
|---|---|
| Surprisingly survivable, effective combined armour especially at the front | Very large and obvious target, and raw armour is rather thin |
| Very high profile; allows shooting over larger cover | Equipping pontoons limits firing angles and makes nearby targets hard to hit |
| Amphibious |
Survivability and armour
At a first glimpse, the armour might look unappealing with weak sides but if one takes a literal dive in the armour profile it will become apparent that the tank isn't built like a conventional tank but like a submarine. It has a light hull and a pressure hull which both are 10 mm with air in-between, which can protect the tank from depths up to 100 m and tank cannons alike, even withstanding low-tier HEAT rounds of large calibres.
The frontal armour of the Ka-Chi will look very similar to that of the Chi-He maxing out at 50 mm, which with installed pontoons, will become even better as the floats act like spaced armour, defeating most HEAT & HE rounds and stop some AP shells that lose their velocity before they reach the main hull. The unconventional armour profile of this tank including the large spaced-out crew makes for a very survivable landship of a tank that shouldn't be messed around with.
With the pontoons installed, two additional features are added: an engine intake stack and a large commander/captain’s cupola. The cupola, however, does not connect to the turret, as its hatch remains sealed. This can deceive inexperienced players into targeting it, believing a shot will eliminate the commander and cause splash damage to the turret crew.
Take note that this is a legitimate concern when facing certain large-calibre self-propelled guns, such as the 15cm sIG 33 B Sfl and Spj fm/43-44, as their high-explosive shells can inflict devastating damage in this manner.
Mobility
While this tank might share the same engine as the Chi-He, it still is larger and heavier, resulting in less power-to-weight ratio and worse acceleration. With the big and bulky profile, it still can keep up with the slower medium and heavy tanks of its BR. Climbing hills and getting around corners will be slightly tougher than the average tank, especially with pontoons installed. The extremely long length of the vehicle with floats can sometimes get the vehicle stuck on sharp angles and drops where the front and back pontoons get stuck on the upper and lower ground and the tracks are unable to catch the ground.
The pontoons also add 2,300 kg of weight, resulting in worse mobility. It makes the amphibious Ka-Chi an even larger target than before, becoming the largest tank in the game in both length and height—Even bigger than the Maus & 2C shockingly. Visibility can be a concern as the front pontoon completely blocks the "Driver's View".
The Ka-Chi is amphibious regardless of whether pontoons are installed or not and can cross bodies of water by itself. The pontoons are for making the tank seaworthy, historically, and for forming a streamlined boat bow for the tank. The Ka-Chi can go 10 km/h (6mph) forward in the water which is the high average for amphibious vehicles, and certainly faster than those that can't swim.
Main armament
Compared to other light and medium tanks at this battle rating, the 47 mm Type 1 gun is quite surprising with 77 mm of penetration at point-blank range and a good reload speed. Plus, this fires APHE shells, which deal great post-penetration damage. Comparatively, the 45 mm 20-K gun on Soviet tanks at ranks 1 and 2 has only 62 mm of penetration in similar conditions.
When the pontoons are installed, the cannon's maximum depression angle is reduced by 3°, making it harder to target close enemies in front of you.
Machine guns
The only functional machine gun mounted in the Ka-Chi is the hull-mounted bow Type 97 machine gun which, once pontoons are installed, is disabled. Only once the pontoons are uninstalled can it be utilized, to very limited extents. It has a narrow arc of firing, small clip size and only fires rifle-calibre bullets: just good enough to deal with trucks and exposed crews but not enough to penetrate a significant amount of armour. It is up to the player to choose between more defensive armour or more offensive firepower.
Usage in battles
When downtiered, the tank can survive hits from most enemy shells at its BR. The surprisingly good armour and the good survivability make it a heavy tank. Its 47 mm gun won't have any trouble penetrating the enemy armour at its BR. The Ka-Chi's armour is thick, but also flat: angling gives the tank a higher chance to bounce shells.
When uptiered it should play as a support tank. Some enemy guns at the higher low tier like the Russian 76 mm ZIS-2 and British 6pdr OQF Mk.III can penetrate the armour of the Ka-Chi without trouble (even when angled). The 47 mm cannon may also begin to struggle to penetrate enemy tanks.
In mixed ground battles, there is a high chance that planes will see you due to its large size so avoid open fields or large areas when planes are in the air. The ability to swim is not a big advantage but on some maps, you can use it to flank the enemy. Swimming also allows the Ka-Chi to take a hull-down position, hiding most of its massive hull underwater.
The very high mounting of the turret allows it to sit behind and shoot over things that most tanks cannot, such as large rocks, lumber piles, and steep hills. This means that it can take hull-down positions that leave only the turret exposed, increasing survivability. One tactic is to use it as a sniper tank or mobile bunker. The punchy cannon and the ability to take unusual positions allow the Ka-Chi to hold down specific areas of the map quite easily.
Another tactic is to use the Ka-Chi as a breakthrough heavy tank. Although significantly riskier, the survivability against low-calibre cannons and HE/HEAT resistance allows it to tank shots and push through enemy lines. Try to keep friendlies close and keep your enemies at a distance as a lone Ka-Chi is easily flanked and swarmed.
The Ka-Chi, like a few other premium heavy vehicles of the rank such as the T-35, Independent, 2C (bis) and Neubaufahrzeug have an unwritten ability to rally friendly tanks when they charge. The stunning mass of the vehicle, its relative rarity, and the fact that it is used by more experienced players can inspire friendlies to group around the Ka-Chi as they are protected behind the large hull and can trust that the player using it will help lead them to victory.
History
With the success of the Navy's Type 2 Special Motorboat Ka-Mi, a more ambitious project to create a bigger, more advanced vehicle was forwarded. Called the Type 3 Special Motorboat, it was not only meant as a fully ocean-going boat but capable of travelling submerged underwater as cargo on the back of a submarine. To withstand the depths (reported as deep as 100 m / 330 ft), the primary pressure hull was a cylinder between 2.0 and 2.1 m (6 ft 7 in) in diameter. Most of the machinery was taken from the Type 1 Chi-He medium tank, presumably to save costs and development time. Like the Ka-Mi, removable sea-going fore and aft pontoons were part of the design, however, they were not required to be amphibious. Navigation was accomplished by rudders attached to the rear pontoon. The vehicle-mounted twin screws could also be independently controlled to maintain a level of steering without the rudders. Nineteen units were reportedly built and extensively tested to success but were never used in combat as they were held back for the defence of the Japanese home islands.
