The YAS is an Abu Dhabi based superyacht. It was originally a Kortenaer-class frigate from the Netherlands launched 3. June 1978 as Piet Hein (F811). After it was decommissioned in 1998 it was sold to the United Arab Emirates and renamed as Al Emirat.
Sea - Private Watercraft
After decommission there it was sold and converted to the YAS.
Links: en.wikipedia.org, en.wikipedia.org