How do people on the bridge know that they are operating within the design limits of the hull?
Ship structures are designed for different ice loads, depending on assigned ice class. This represents operational limitations for the ship in order to avoid structural damage.
How do the people on the bridge know that they really are operating within those limits, particularly under low visibility in darkness, fog and/or under heavy snowing conditions?
Operation of vessels within those limitations is a key challenge for the people in command.
Extensive practical experience from ship operations in ice, and knowledge about the individual vessels and their specifications, have so far been essential elements to avoid damages.
Technological solutions
Now, we see a trend where ship operations in ice-infested waters are increasing, with growing ship sizes, and in many cases less experienced people involved than before. The perception of ice conditions and actual stresses on hull structure is a major challenge, particularly in darkness and snowing conditions. Real-time information about ice loads on the hull structure, as decision support for navigators on the bridge, is more needed than ever before.
During the past three years, DNV has been developing technological solutions for ice load monitoring to enhance safety and regularity for ship operations in cold climate. The project culminated ultimo 2008 after the development of a comprehensive decision support tool for transiting ice. The system has been tested over the past two winter seasons onboard the Norwegian coast guard vessel KV Svalbard, operating extensively in various Arctic ice conditions. It has been important to develop and test the system over an extended period of time under different ice conditions, since ice conditions are so variable and it was necessary to make sure that the system is working under various circumstances.
Real-time ice load information
The system includes fibre-optic sensors (suitable for installation in gas-dangerous spaces) that measure shear strain on the vessel’s hull and electromagnetic equipment, which measures the thickness of the ice in the ice belt in way of the bow. This information is analysed and displayed on the bridge. Additionally, meteorological and satellite data about the ice is integrated into electronic charts allowing for optimum route selection.
Real-time ice load information is essential to avoid damages. The system is providing essential and simple information to the bridge about acceptable loads, borderline loads or overloads. Or expressed in other words: go ahead, caution or reduce/stop.
Leading and unique
Based on the success of the Ice Load Monitoring project and a thorough understanding of the risks associated with Arctic operations, our conclusion is that technology will not be a showstopper for safe, well-planned ship operations in Arctic waters. We are ready to apply this technology now.
This system is leading and unique. Our goal is to maintain high competence levels and updated rules and notations so that DNV is able to provide owners, yards and oil majors with state-of-the-art technology and the support they need to safeguard their cold climate activities.
DNV is currently involved in major projects where Ice Load Monitoring will be applied both for ships and also for offshore structures, as decision support for ice navigation and ice management.
The Ice Load Monitoring project was headed by DNV and supported by the Norwegian Research Council. Other partners were Teekay, StatoilHydro, Light Structures, The Norwegian Meteorological Institute, C-map/Jeppesen and the Norwegian Coastguard.