# Ship stern designs



## hilifta (Feb 12, 2006)

Can any body tell me why some cruise liners sterns have been altered in such an ugly fashion.
I refer to the Athena ex Stockholm, the Island Star, Pacific Star and Pacific Sun, and others.
I have recently cruised on these last two and can't help but notice how appalling they now look compared with their original shape. One viewer on another site simply commented on a photo of the Pacific Star's stern, " a (rubbish) skip with windows".
I'm inclined to agree.
I recall a few years ago talking with one of our Masters on the 2 day weather delay he had just experienced and he told me me that ships with these very cut off straight sterns were mongrels in a following sea. He had to hove too.
If this is so then why are so many cruise liner being altered and given such a stern.
I notice that Jubilee's 2 sisterships have a very different shape, one has some curved section at water level on the stern, whilst the other has not been altered at all.
Can anybody shed any light on this subject.

Rgds/Mike


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## chadburn (Jun 2, 2008)

I think it is to do with the "Watercraft Toys" they carry for the Passengers enjoyment as they now appear to have a "garage" in the stern. It is true to say that straight sterns can be a pig in a following sea especially when just entering into the confines of a harbour mouth.


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## eddyw (Nov 6, 2007)

I think that in the case of Athena the additional structure at the stern was added to meet SOLAS stability requirements. Otherwise, I suppose transom sterns are cheaper to build.


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## fred henderson (Jun 13, 2005)

*Transom stern*

Almost all merchant ships built in the last twenty years have a transom stern, because this shape provides the most effecient hydrodynamics, with a lower powering requirement to achieve the design service speed. Warship designs have used transom sterns for decades to obtain a higher speed from the available power.

In a following sea a ship with a transom stern will experience increased hull vibration. During the 1960s the Costanzi stern was developed to overcome this problem in passenger ships. This has a transom stern below the waterline and a cruiser stern above. Queen Mary 2 is fitted with a Costanzi stern optimised for podded propulsion.

Fred(Thumb)


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