Eva Grey: What are some of the advantages of creating sister ships? Denis Morais: The purpose of sister ships is that when you have a manufacturing project, you want to maximise your facilities and processes and all the effort that goes into building one vessel and you want to re-use that by building multiple vessels.

In the shipping and cruise industry, "sister ships" are built primarily for economic efficiency and operational consistency. When a company like Royal Caribbean or Maersk designs a "lead ship," the engineering and design costs are astronomical. By building three or four "sisters" from the exact same blueprints, the company can spread those initial R&D costs across multiple vessels, significantly lowering the "per-ship" price. Construction is also faster because the shipyard's workers are already familiar with the layout. Operationally, sister ships are a massive advantage: crews can be rotated between ships without needing new safety training, and the company can maintain a standardized inventory of spare parts, which is vital for mid-ocean repairs. Furthermore, sister ships allow a brand to offer a consistent customer experience; a passenger who enjoyed a specific layout on one ship will feel "at home" on its sister. In 2026, this "class" system remains the standard for almost all major commercial maritime expansions.