One of the Ambient Structures from Katters Structures.
There are two kinds of Ships:
Villager manned merchant ship.
And Pillager manned battle ships.
The main blocks are :
In Villager versions you can find maps to most Structures in Katters Structures inside chests
Ocean ships, will naturally spawn in Oceans and their corresponding Biomes O' Plenty and Terralith Biomes.