Jumboization is a technique in shipbuilding consisting of enlarging a ship by adding an entire section to it.
By contrast with refitting or installation of equipment, jumboization is a long and complex endeavour which can require a specialized shipyard.
[1] Large ships often have a long midsection with a uniform profile.
In such cases, the ship is cut in two pieces and an additional section is inserted in between.
The tanker Seawise Giant became the largest ship in the world after her jumboization.