Wiktionary
n. (context nautical English) a ship built to the same design as another.
WordNet
n. a ship that is one of two or more similar ships built at the same time
Wikipedia
A sister ship is a ship of the same class as or of virtually identical design to another ship. Such vessels share a nearly identical hull and superstructure layout, similar displacement, and roughly comparable features and equipment. Often, sisters become more differentiated during their service as their equipment (in the case of military ships, their armament) are separately altered.
For instance, the U.S. warships , , , and are all sister ships, each being an .
The most famous sister ships were the White Star Line's , and . As with some other liners, the sisters worked as running mates. Other sister ships include the Royal Caribbean International's and .
Half-sister refers to a ship of the same class but with some significant differences. One example of half-sisters are the First World War-era British s where the first two ships had four guns, but the last ship, , had two guns instead. Another example is the American s of the Second World War that came in "long-hull" and "short-hull" versions.
The generally accepted commercial distinctions of a sister ship are the following:
- Type: Identical main type (bullk, tank, RoRo, etc.)
- DWT: ± 10 % on the DWT (If the ship is 100,000 DWT, 90,000 to 110,000 DWT)
- Built: ± 5 years (if the ship is built in 2000, built 1995 to 2005)
- Builder: Identical shipbuilding company name (not the ship yard location or the country of build)
The critical overriding criteria are the same hull design. For example, the popular TESS-57 standard design built by Tsunishi Shipbuilding are built in Japan, China, and the Philippines. All the ships of this design are classed as sister ships.
The International Maritime Organization defined sister ship in IMO resolution MSC/Circ.1158 in 2006. Criteria included these:
- A sister ship is a ship built by the same yard from the same plans.
- The acceptable deviation of lightship displacement should be between 1 and 2% of the lightship displacement of the lead ship, depending on the length of the ship.
Usage examples of "sister ship".
The dying cruiser breaks up as spectacularly as her sister ship, raining debris across the entire western hemisphere as she disintegrates.
He'd studied the Andre Notion's designs-it was the sister ship of the Arrakis-so throughly he could close his eyes and still put anything in place.
Neither Captain Quacho of the sister ship, the Arapahoe, or Captain Osullivan of the Genessee had expected that the refugee Hiver ship would be attacked by its own species, its queens driven to escape in the pods which had then been summarily disintegrated by the planetary batteries.
The upshot of that interview was that Thian made a second contact with the KLTL, conversing this time with their life-support systems officer and discovering that yes, there were available sgit plant shoots that could be spared and possibly more from their sister ship in the squadron, the KLTS.
Moving out at last, an armoured Colossus, sister ship to that other Titan that had destroyed the Hood with one single, savage blow, the Hood, the darling of the Royal Navy, the most powerful ship in the world, or so men had thought.