Forth Ports Authority beat off stiff competition to become the new owner of the Royal Yacht Britannia when she was decommissioned in 1997.
Scottish-built Britannia is currently moored at a temporary berth adjacent to the Ocean Terminal site at Leith and will move to her permanent home alongside the complex when it opens late next year.
'Britannia was built in Clydebank and launched on 16 April 1953 and is the last in a line of royal yachts stretching back over 300 years, ' says Mott MacDonald consultant Alastair Soane. 'The yacht will be the focal point of Ocean Terminal and the complex will also house a new visitors centre on the second floor from where an elevated walkway will provide direct access to Britannia's deck level.
'Companionways on the yacht are extremely steep, presenting inherent safety risks and greatly restricting disabled access.
Nonetheless, easy entry routes at both Britannia's temporary and permanent moorings were essential.'
Visitor access at the temporary mooring is provided by a steel tower designed by Mott MacDonald. The tower has a central lift shaft, surrounded by a staircase with gangways leading to each level of Britannia.
'A similar tower has been designed for the Ocean Terminal, with the exception of the elevated walkway from the visitors centre, ' says Soane. 'We designed the temporary tower to cope with water level fluctuations and movements within the harbour.
Fortunately, water levels within the Port of Leith are controlled by a lock system which reduces the tidal effect but does not stop all water movement.'
Horizontal movements of the yacht are kept to a minimum by highly tensioned moorings but the potential for small vertical and horizontal movements had to be incorporated into the design. The access gangways are pinned at the tower end while the other end rests on the deck.
'The deck end of the gangway has a series of rollers beneath it which allows it to move over the deck, taking account of both minor vertical and horizontal movement.