Really seems like OP doesnt really understand that there can be a plethora of factors that lead to a round penetrating or not, and also doesnt understand how the crew system in this game works. I’ll compare the Scharn and the Mutsu because those are the vehicles OP mentioned.
You will have to clarify what you mean by “shots with 100% chance of pentration”. The whole issue you are having is that these shots you are firing are not penetrating, yet others seem to be perfectly capable of doing so, so have you considered that maybe what you think should be penetrating is in fact the issue, not what is actually happening. Lets look at the armour on the Scharn to start, it has 320mm main belt, then a 105mm turtleback plate behind the main belt that covers the machinery space. The barbettes are 350mm thick, and are also behind the main belt.
General battle ranges are 7500 to 15000m, so I will use the 7500m pentration values for the 16" No.5 APC shell the Mutsu uses. As you can see in the screenshots below, this round is unable to penetrate the belt and turtleback armour of the Scharn when fired from 90 degrees broadside, in the best case scenario.
This is your first problem, that if you hit the most armoured part of the Scharn, then you will not be able to do any damage at all.
However, if you are able to land your shells below the waterline, then you will be able to penetrate this weakly armoured part of the hull and will be able to do damage.
In reverse, the Mutsu has 304mm of main belt armour, and a 76mm angled plate behind it. This second plate is consierable less angled than the turtleback plate on the Scharn, so is considerably less useful, as well as being thinner. The Barbettes are 304mm thick, but are not covered by the belt armour at all. This armour profile is much worse than the Scharn, and as such with the Scharn shooting the 11" Psgr. L/4.4 APCBC, replicating the first shot, again in optimal conditions shows that the Scharn is in fact capable of pentrating the Mutsu’s belt and causing internal damage.
Similarly, when the shot is placed underneath the belt armour, the round will penetrate an reach the machinery spaces.
All of this said, even without taking angling into consideration, the Scharn has a large advantage in terms of armour and despite the lower penetration, is still very capable of pentrating the most armoured part of the Mutsu whereas the Mutsu has to lan shells underneath the belt to reach the machinery spaces, which is the most impartand part on any ship, and I will get to why in a minute.
It is very easy in GRB to recognise when and by how much another player is angling their vehicle, but it is much harder in naval, though it does still have the same effect on armour and penetration.
The turtleback armour plate on the Scharn is already very angled, and as such its effective thickness is greatly increased as can be seen below.
When the main belt armour is angled, it also quickly increses in effective thickness, as shown here:
It is fairly needless to say that this is practically unpenetrable by anything in game, and the same is true for the Mutsu.
It is important to note that, on both ships shells that hit under the belt will still easily penetrate and reach the internal spaces, even at these extreme angles.
This means that on top of the advantage the Scharn already has, if it angles it can effectively mean that you are unable to penetrate even the weaker parts of its belt armour, however this does decrease the areas the Scharn can effectively penetrate. Overall, this means that there are several ways that you or the enemy can make it considerably more difficult for your ship’s armour to be penetrated. You really should be angling in any engagement, and attempting to make it so that the way the enemy’s angling is less effective and I suspect you are not doing this at all, and are just sitting in gunner view shooting at whatever you see, I have made some images below to display what i mean.
I’m sure you get the idea, and though it will never be this cut and dry in a match, if you can try and use this angling you will find that you will take less penetrating shots, and if you can recognise how the enemy is angling you can potentially re-orient yourself to get better shots on target.
The next thing that I do not think you fully understand is the crew system. The crew in your ship is distrobuted unevenly in the critical parts of each ship, and can be seen in the hangar. Crew count matters a lot in naval, and for the ships we are comparing, there is quite a large disparity, with the Mutsu having just over 1300 crew, and the Scharn having just over 1900. This means that the Scharn will inevitably be much more survivable in any given fight.
As can be seen here, the majority of the crew is in the machinery spaces, which is why I said earlier that it is the most impartand part of the ship. Obviously Ammo racks will cause greater crew loss than anything else, and can oneshot ships, but if you are talking about the survivability in terms of crew these high crew density spaces are the most important parts of ship for its survivability. With the crew distrobution shown, it is not surprising that a single penetrating hit that bursts in the machinery spaces and destroys several boilers will cause a high percentage of crew loss, and it is much easier for the Scharn to hit and penetrate the larger and less well protected areas of the Mutsu that the crew is located in, than it is for the Mutsu to do the same. The level of crew will only mitigate this slightly, and ultimately if a shell destroys critical components in a very crew dense area it will do a lot of damage.
This is another area where the Scharn is a significantly superior ship to the Mutsu, and I’m sure you are seeing a trend here.
The last thing I want to talk about, is aiming. There are naval players who will vehemently deny that aiming really matters in naval, and you should focus on hitting the target as much as possible, but it isnt possible to aim for specific components of ships at longer ranges, and there are also people who will argue that you can aim for specific components, and can reliably hit them at longer ranges. I think ping will greatly effect this, and it will be different for different ships with the different dispersions, but overall I think you can aim for specific components, and can reliably land hits in a specific area of a ship, but you cannot reliably hit specific components of ships at longer ranges, and I will explain how I think this works. In the game currently, there is a natural spread at even point blanc range. This means that there is a rough oval in the water where the shells from any given salvo will land. When firing at longer ranges, the dispersion naturally increases and so this oval gets larger and larger. Given that the crew dense vital components of any ship are generally lower down, usually below the waterline, under-ranging is generally the best way to hit critical components, and leading the target more than the indicator tells you to(if you want to aim for magazines), by half a shiplength or a little less, should mean that the oval where the shells can land covers the part of the ship you want to hit, and from here there is mostly just luck involved, waiting for hits on the specific components you are aiming for.
I believe this is more effective than just lobbing shells that are generally on target but with no specific aiming point, as it greatly increases the chance of hitting a specific component that will cause meaningful damage.
Overall, the matchup described in this post is not a balanced matchup, the Scharn is far superior in just about every way to the Mutsu apart from raw penetration, which as I have talked about doesnt really matter given the specific circumstances. What OP thinks he should be able to do is not really based in reality or in a good understanding of the game mechanics. There are definitely bugs and issues with the armour/ammo mechanics in game, and ping can greatly effect one’s experience, but overall the system works, it just needs to be understood properly.
