Jumboization

Jumboisation is a technique in shipbuilding consisting in building or enlarging a ship by adding an entire section to it. By contrast with refitting or installation of equipment, jumboisation is a long and complex endeavour which requires a specialised shipyard.

Enlarging a ship by jumboisation allows to increase her value without needing to purchase or build an entirely now one. This technique was used on cruise ships, oilers, but also smaller units like sail ships or fishing ships^[1].

Jumboisation can be performed in several ways.

Large ships have a long middle section with a uniform profile. In such cases, the ship is cut in two halves and an additional section is added between the aft and bow parts before welding. Operations are performed in a dry dock.

Smaller ships, below 80 metres, are usually jumboised by replacing the whole aft or bow part of the ship. Indeed, the shape of their hull is usually incompatible with the previous method.

Typically, the additional sections are 20 to 30 metres long, corresponding to an oiler citern, a cargo ship hull, or a flock of cabins on a cruise ship. Oiler Knock Nevis became the largest ship in the world after her jumboisation.

• Photographs of jumboisation of cruise ship Enchantment of the Seas