The Ship is too little to build a Titanic...
The Titanic is 28m wide, not 10m.
Walls in Minetest are 1m thick, so you need additional space.
You see up to 12 Walls alongside, so the minimal with of the Minetest-Modell should be 40m.
The length of the Titanic was 269m. So the Minetest-Modell should have ca. 384m.
My advise is: Build the cabins first and then the outside. And build it realistic. Not a smaller top deck when the original is not smaller. Use what you have learnt form the first try for the second.
And use enough time. Not only days, months.