How to fix "Hull is too narrow"

[FMBluecher]

On my first game of RTW3, but I have dozens if not hundreds of hours in RTW1 and 2, and I've never seen this message before when trying to design a BC:

"Hull is too narrow for speed > 18 kt and triple/quad turrets in A or Y positions and TPS more than 1."

FWIW, the AI auto-designs ships for me that also throw this error. Design in question is a 32,000-ton BC with (as the error implies) triple 15-in turrets in the A- and Y-turret positions and TPS level 2.

If I change the TPS down to level 1, it gives me the following error:

"Hull is too narrow for speed > 23 kt and triple/quad turrets in A or Y positions and TPS more than 0."

What do I need to change about the design to make it legal? Is there no way to have a design with triple turrets, battlecruiser speed, and TPS, or does the displacement have to be huge? I've experimented with hulls as large as my industry allows (35,500 tons) and it still throws the same error. I have consulted the manual and drawn a blank. Thanks for your help!

[rs2excelsior]

You either reduce speed, reduce TPS, or don’t put triples in A and Y positions. Or you wait, because the restrictions do loosen over time. That’s all you can do. It does not, as far as I’m aware, depend at all on gun caliber or ship displacement.

I am of a mind that that check could use a rework. I like that it’s there in some form, so that there’s a reason to use triples over twins in certain cases like some IRL treaty cruisers, but it does mean some of historical battleship designs aren’t possible at the time they were historically built without compromising TPS.

[FMBluecher]

Thank you very much! How will I know when the restrictions loosen? Is it a tech, or does it just happen?

[rs2excelsior]

It just happens over time, though I think there’s a ship design tech that gets rid of it entirely

[twent]

It just happens over time, though I think there’s a ship design tech that gets rid of it entirely

Yes, indeed, there is such a tech.
It is located under the "Ship design" branch and (as of version 1.00.79 beta in 2025-March) it is entry number 25.
It has a tech-base-year of 1932, it does spread once a nation unlocks this tech.
Its description text is, as follows: "Allows triple turrets in all positions regardless of speed and TPS".

Edit: By the way, I agree, this "limitation" should be revisited, and if no good solution can be found, it should be removed because, as stated earlier in this thread, it prevents players from attempting historical-build-recreations in the game.

[Dasein]

If your ship only uses two triple turrets you could kind of avoid the problem installing those turrets in B and X positions, although they'll weigh more than in A and Y positions.
But if your design uses 3 triple turrets I'm afraid there's not much we can do until the technology is researched in the 1930s.

Until then either 3 triple turrets in B, X and a central position like Q or only 8 guns in A (twin), B and X are probably the best solutions for a fast ship.

[WLRoo]

Note that you can use All Forward Main Armament at any point - the tech only enables weight saving from such designs - and those also ignore the speed/TPS restriction.

Not tried an A,B, X layout to see if that is acceptable.

So I'm just trying to figure out which real-world designs the game considers 'illegal' for speed/TPS/turret layout.