A spacious glass dome, the first of its kind on board a cruise ship, engineered to withstand the forces at sea, while giving passengers spectacular uninterrupted views of the sky and the ocean.

Iona, P&O’s latest and most sustainable cruise ship, will be the first in the world to run on liquified natural gas. The ship features a range of entertainment options for its 5200 passengers, including a spectacular new venue, SkyDome. Spread over two decks, the space features a poolside environment by day that transforms into an entertainment venue at night, set beneath a spacious glass dome that allows uninterrupted views of the sky, the sea and the shoreline.

Designed by Eckersley O’Callaghan, SkyDome is the first structure of its kind and represents a significant engineering challenge. Measuring 41 metres long, 29 metres wide and four metres high, the glass-domed roof must allow for numerous movements and loads imposed on it, from the deformations of the ship due to the wave loads, to the vibrations created by the ship’s engines. This has meant that, rather than being completely fixed, the SkyDome can move independently from the support structure in certain places. Performance mock-up testing has been carried out to ensure the structure can withstand the most extreme weather events.

While we always aim to deliver the most slender and elegant structures, in this case minimising weight has been of particular importance, because it impacts on the overall ship design, affecting the buoyancy assumptions and how the ship will sit in the water. 

During design development we used Digital Design tools, creating a custom script to automate the beam sizing to minimise steel tonnage. Automated beam sizing isn't innovative in itself, however our novel implementation accounted for the global buckling behaviour, which is often critical in the design of grid shell structures.

Unlike buildings, which are static, a ship is always moving, meaning there is no side that permanently faces north. This affects the way we control factors like environmental performance, because the angle that sunlight enters the ship is constantly changing. We must consider which glass type and glass coatings to use to ensure views out of the SkyDome are as spectacular as possible, while ensuring the interior doesn’t become uncomfortably hot or cold, depending on the external climate.

A lack of similar precedents in ship design has meant that our extensive expertise in structure, glass and facade engineering has been crucial in convincing the relevant regulatory bodies of the design’s code compliance.