We know very little about the "Battleship" in Legend of Korra. It appears to have been a multi-national project as many of its features make no sense if you only have one group of benders. In fact how you're supposed to sink a warship IN GENERAL with this design is largely up for debate unless we're expected to believe that they continued to fight like Greek triremes ramming into each other while trying to knock out the superstructure with bending. I personally believe that the guns can be used secondarily as a track/aiming apparatus for bent shells similar to the ice torpedoes seen on The Day of Black Sun, Part 1: The Invasion. https://avatar.fandom.com/wiki/Ice_torpedo There would be other versions for metal benders, earth benders, and fire benders. If I'm being honest this battleship is more of an armored cruiser as the main guns only have a maximum caliber of 9 inches (228.6 mm) and that's stretching it. They are more likely somewhere in the range of 5in (127 mm) to 6in (152 mm) in caliber.

The scale is 1:1000 based off of the The Legend of Korra: Air (The Art of the Animated)
https://i.imgur.com/xbsDKJq.png
(the person in the picture is around 1.7m tall for reference)

UPDATES:

Added my version of the ship using a dynamite gun so as to not break with the lore (of not having gun powder) this ship is armed with five 15in/36caliber guns for the main battery, nine/ten 5in/25caliber guns for its secondary, and a tertiary battery of two 6in/50-54caliber guns.

models used

タツノオトシゴ（Seahorse）3Dデータ
https://www.thingiverse.com/thing:182265

Chinese dragon v2.1
https://www.thingiverse.com/thing:3657151

Medium scotch marine boiler
https://www.thingiverse.com/thing:49799

Scale Ship Dorade (ventilation tube)
https://www.thingiverse.com/thing:2262971

Fast Load Cannon 2
https://www.thingiverse.com/thing:3762014

HTMS THONBURI เรือหลวงธนบุรี 1/72 scale
https://www.thingiverse.com/thing:5173842

HMS thunderchild by drach
https://www.thingiverse.com/thing:4791135

EPIC SCALE FIELD ARTILLERY
https://cults3d.com/en/3d-model/game/epic-scale-field-artillery

Pagoda [Cake] decoration
https://www.thingiverse.com/thing:5189312