SOLAS and ORIANA's new duck tail

Since it has been revealed last week that ORIANA is soon to be bear a ungainly 'duck tail' which will have the undesired effect of destroying the elegant stern lines of the ship, which are considered by many to be among the finest looking stern on a modern passenger liner.
Although no mention has been given by P&O to the additional structure Blohm + Voss have mentioned briefly that ORIANA would be fitted with a duck tail appendage to allow the ship to retain stability with the new cabins being fitted.
Another ship of almost the same age as ORIANA, Royal Caribbean's SPLENDOUR OF THE SEAS who is currently being refitted in Cadiz is having refit to increase her own Cabin balcony number is also having duck tail fitted which was described by RCCL's Fleet Director, Marine Operations as helping to balance the ship and also improves efficiency in moving through the water.
There is also some thought that it is not being solely installed because of the new cabins but also because of a pre existing stability issue however from personal experience of being on board ORIANA during less than favourable weather conditions I can quite honestly say that the ship has excellent sea keeping properties.
Indeed during her Maiden Voyage her captain Commodore Ian Gibb expressed his thoughts about her performance in an interview shown below


Another thought is that ORIANA is being upgraded to meet new SOLAS regulations which came into affect in 2010 requiring it in the design to provide extra stability.
In light of the ships such as the Solstice Class ships, and NORWEGIAN EPIC who both feature one in their design.
However it is worth noting that another class of Meyer Werft ships the Sphinx Class of AIDA Cruises the latest of which were launched in 2010 and earlier this year do not feature the 'duck tail'.