The Stirling Iona is a sensible ship
in a world populated by exotica, and it is possibly a move back towards those basic
requirements which motivated the British ship-owners in the 1970s. They wanted to provide
ships which would carry out all the tasks which might be required of them by the fledgling
North Sea oil industry. And since most of the objects out there were floating, anchor
handling and towing was the first requirement followed by an ever increasing supply capability.
The progress of the floating objects out into the deeps has encouraged
numerous ship-owners to built larger and more powerful vessels with the capacity to store
thousands of meters of large diameter wire on their work drums; or in some cases
sufficient rope to tie said objects to the seabed with a variety of unusual anchors.
However there is still a need for medium sized ships capable of moving semi-submersibles
from one point to another in water depths of less than 700 meters and capable of towing
and supplying both semi-submersibles and jack-ups in areas less well served with marine
support than the Shetland Basin. Presumably this the market that the Stirling Iona is
intended to serve, and even though the winch appears to take up little space on the deck,
the work drums are sized for 1390 meters of 76mm wire.
In a style which reflects the earliest anchor-handlers the winch is
completely exposed, allowing those at the controls of the ship and the winch to see
exactly what is happening down there.
Although the VS473 first appeared in about 1983 this ship is only a
little like the original. The design benefits from the developments in engines, and the
prime movers are shoe-horned in under the accommodation with long shafts to the gearboxes
and the screws. In what seems to be accepted as the British approach, mud and brine tanks
are ranged down either side of the underdeck space aft of the engine room - designed to
avoid internal framing, and the dry bulk tanks are set down the centre. Fuel and water are
mainly contained with the double hull and the forward and aft tanks.
The two Wartsila 12V32 engines develop 15,000 bhp between them giving
the ship a maximum bollard pull of 172 tonnes and a maximum speed free running of 16 knots.
The wheelhouse is particularly impressive, and it is obvious that
some-one within either Stirling or Fergusons or both have taken the trouble to think out
the layout of the controls so as to provide the ship driver and the winch driver with the
means of carrying out their function without having to have arm extensions fitted. The
design of the forward controls is particularly interesting, grouping the dials and levers
on two consoles to allow the driver to step forward to see what is happening outside.
Extract from article in Offshore Support Journal May 2000.