Ice-breaking shallow draft AHTS challenge

IJmuiden, 28/08/2009 2:51pm

OSD-Holland has been commissioned by Silverburn Shipping Group (SSG) to design a shallow draft offshore supply vessel with ice breaking capability. It has to be capable of worldwide AHTS service, but also has to be optimised for Caspian Sea and Russian river service. The vessel will have to be able to provide 40 tonnes BP while on a shallow draft of 2.5 m, and also have a significant load carrying capability at this draft. The vessel will have to be able to break ice up to 70 cm thick. The challenge is to design a vessel which is strong enough to break ice yet light enough to carry cargo on a shallow draft. It also has to be a very rugged and simple design, able to operate and be maintained without extensive support. No high tensile steel could be used and a conventional dual diesel direct drive power plant with shrouded propellers has been chosen.

The basic design challenge has been met by increasing the beam of the vessel to generate load capacity on a shallow draft. Due to this the vessel now has a higher GM. Model tests at a 1:10 scale have been conducted at Aker Arctic to enssure the hull form can break ice to Finnish/Swedish Ice Class 1A standards. The tests showed that the extreme B/D ratio will deliver the performance required and the design which was developed in close cooperation with the Newbuilding Project Team of SSG, is now out to tender at a number of yards.

Main dimensions are LOA 49.6 m, beam 16.5 m, seagoing draft 3.5 m, shallow draft 2.5 m.