Tough tests for Caspian anchor handler

IJmuiden, 14/01/2010 4:22pm

Silverburn Shipping Group is poised to place an order for the first of a series of unusual ice breaking anchor handlers. They are specifically designed for use in the Caspian Sea and so must be able to work in heavy ice, but still have a significant load carrying capacity on a shallow draft.

The Caspian Sea and Russian rivers are a demanding environment in which Silverburn has extensive experience. They turned to IJmuiden-based OSD-Holland to produce a design for a very robust and simple to repair AHTS which can carry out platform supply in shallow waters and heavy ice, but also retain the flexibility to trade worldwide.

"We worked with Silverburn to design an AHTS which can work in 70 cm of ice," says Michiel Wijsmuller, managing director of OSD.  "It has a significant load carrying capability on a shallow draft and provides a minimum 45 tonnes BP. Main dimensions are LOA 49.6 m, beam 16.5 m, seagoing draft 3.5 m, shallow draft 2.5 m.

High quality shipyards are few in the Caspian area so Silverburn insisted that the vessel be simple, very rugged and easy to repair. A conventional dual diesel direct drive power plant with shrouded propellers was chosen as a proven and easily maintained system. "Only mild steel is to be used in the build, so we had to reconcile the need for a structure which is light enough for shallow draft but strong enough to work in ice," explains Wijsmuller. "A wide beam and careful attention to detail in the hull shape are the keys to that. Model hull tests at Aker Arctic have proven the shape, which although it produces a high GM minimises the reduction in sea keeping ability through clever design features."

1:10 scale model tests at Aker Arctic showed the hull form can perform in ice to Finnish/Swedish Ice Class "1A Super" standards with relatively little modification.