The tier 7 Japanese heavy tank O-Ni is a slow heavily armored tank that like many of the Japanese heavy tanks has above average frontal/rear while sacrificing side armor protection. The side armor is only weak when enemies fire directly at it due to the very thin armor found on the side hull. O-Ni drivers can however angle their frontal armor while keeping their side armor at an auto-bounce angle to improve the frontal armor on the hull which is somewhat weaker than you would expect. This guide will outline all World of Tanks O-Ni weak spots and also break down the armor to provide effective armor values. Green areas are the weakest armor found in a specific area on the O-Ni, followed by yellow/orange, and finally red areas are the toughest armor to penetrate. Purple areas have no hull armor to cause HP damage and/or have a high chance of a zero-damage critical hit. White areas are sections that are usually at a 90 degree angle and thus will auto-bounce any rounds thrown at them, but due to the views I use to create these guides they are visible.
World of Tanks O-Ni Weak Spots Frontal
Frontally the O-Ni is somewhat of a disappointment considering its poor mobility but it still manages to have enough sections above 235mm effective armor to protect it from most tanks it face off against. Starting on the lower hull you have the lower glacis having only 193mm effective armor while the armor above it has 203mm effective armor. This is weak enough for many tanks to penetrate the O-Ni but it will still provide protection against some tier 7 tanks and under. The drivers plate is better protected outside of the 0 armor hole with a 247mm effective armor value with the cheeks being virtually immune from the front.
Moving further up the O-Ni’s frontal armor you have two small turrets that are viable weak spots if you stick to the sections around the guns that are not angled since the further you move away from the guns the stronger the armor. The angled armor plate located behind the small turrets has the same armor as the drivers plate(175mm at 45°) giving it 247mm effective armor and immune cheek sections.
The turret of the O-Ni is a tough nut to crack from tier 7 and lower tanks but isn’t overwhelming to face off against. This armor guide uses the 10cm experimental gun which has a stronger mantlet, with a minimal 250mm effective armor rating on the sloped sections around the gun. The flat sections located further back on the turret(still on the mantlet) only has a 200mm-205mm effective armor rating and is semi-weak. If the O-Ni uses the 15cm most of the mantlet is 200mm effective armor and just below the gun actually only has 35mm(eek) effective armor. Outside of the mantler you have a small red strip of 220mm armor and then the orange area drops down to 200mm thick. Both areas are not angled that well and respectively have 226mm effective armor and 205mm effective armor. Avoid the turret sides since they are angled very well and will pose problems for any tank deciding to shoot at them.
Finally the commander’s hatch on top of the O-Ni is fairly easy to deal with. The center mass of the hatch has 152mm effective armor and as you move out towards the edges the armor drastically increases. Therefore, you should either stick to the center of the commander’s hatch and if you have borderline penetration for another above 152mm then you should aim somewhere else.
World of Tanks O-Ni Weak Spots Side
The O-Ni’s side as mentioned earlier is very poorly armored and is actually weaker than the rear armor. There is a 35mm spaced armor plate covering the lower side hull and also 40mm tracks but it still doesn’t make up for the very thin side hull armor on the O-Ni. The upper side hull is only 70mm thick above the spaced armor/tracks while behind the spaced armor drops down to 35mm. If you have a shot on the side hull simply avoid using HEAT on the spaced armor section and you will have no issues with the side armor on the O-Ni. If you aim higher up the small turrets and side turret armor is a minimal of 152mm effective armor which is still weak at tier 7 but significantly stronger than the hull armor.
World of Tanks O-Ni Weak Spots Rear
While the rear armor of the O-Ni is stronger than the side armor it is still unable to give it viable protection at tier 7 unless you angle it(while keeping the sides at an auto-bounce angle) properly. The rear hull and rear turret both have 150mm thick armor and the commander’s hatch is protected the same as the front/side. There are a few small areas on the engine deck that are only 30mm and able to be overmatched by a 90mm+ round. The red area is stronger but when overmatching it will be easy to penetrate while the green engine deck area is weak even with its impressive angle. If you approach the rear of the O-Ni with the “keep it simple” mindset and just aim at the large flat areas you will have no problems against it. The small “trick” weak spots are there for if the O-Ni is behind cover or you need to get a quick shot off.