Grembore

Hello, I've got a few questions regarding the containers which can be found in the Armory. I have played the game 2 or 3 years ago, but section is new for me. Is it worth to buy containers for coal? Is it possible to get a premium ship from these? Which one is the better? If there is :) I've got 17k coal, what I can spend for these boxes (if its worth the coal :)) Thank you very much in advance!

Thank you so much for both ideas :)