guessing its a similar thing to people that are getting bedrock tiles in a straight line like that when leveling ground. Does it act like water and just have the wrong texture or do the ships hit it?

Try re-verify your files in steam before you load into the game next time. I find that clears many glitches. It might help with this too. (Right click on the game in your Library, then Properties - Local Files - Verify)

im having the same issue on my seed idk wtf it is