New Resonance Alerts From AWT
Applied Weather Technology (AWT), announced that its Route Optimization Service -- used by approximately 1500 ships each day to help identify the safest, most time-efficient routes to their destinations -- now includes technology that helps warn ships at sea of the potential for resonance, a physics phenomenon that can cause ships to severely roll and lead to crew injury and cargo loss.
With the addition of "resonance" technology to its Route Optimization Service, AWT is the only shore-based ship routing company to offer severe motion alerts /resonance alerts to ships based not only on the weather, but also on the vessels' size, draft, stability, heading and wave conditions.
One of the reasons why a ship might suddenly and severely roll is due to resonance, when the roll period of the vessel and the wave period relative to the vessel are nearly the same. When this happens, a vessel can go from slight or moderate rolling, to dangerous 35+ degree rolls very quickly. Violent rolling can cause cargo to shift or break loose, which can change the stability of the vessel and further endanger the cargo, vessel and crew.
Previously the industry standard was to only intuitively take into account the stability of a specific vessel when analyzing how a ship might react to certain wave or weather conditions. Now, AWT's Route Optimization Service analyzes criteria specific to the vessel in addition to the wave conditions to anticipate the motions that each vessel might experience that could lead to resonance and severe rolling. Different vessels going through the same weather could experience dramatically different motions, depending on factors such as the ship's speed, length, beam, draft or stability.
On average AWT monitors approximately 1500 vessels and fields between 10-30 resonance alerts each day, depending on the time of year and weather patterns. AWT evaluates each alert and sends a course change and/or a speed recommendation to the ship in the cases when the company believes the vessel may experience a problem. The alerts show where severe motions are most likely to occur at a specific time along the vessel's route, and indicate which headings and/or speeds could be used to avoid these areas, thereby minimizing the potential of heavy weather damage. These types of alarms allow AWT to find the most efficient route while helping to keep the crew, vessel and cargo safe.
On November 21, 2008, one of the vessels being routed by AWT experienced a motion alert for the possibility of severe rolling from a developing storm moving east-northeast from Japan. If the vessel had maintained its course along 35 degrees north latitude, it would have encountered gale- to storm- force winds, 7-9 meter waves and the possibility of severe rolling on November 25. The alert not only helped the AWT Route Analyst decide to divert the vessel down to 32 degrees north latitude, it also indicated what headings and speeds were needed to safely clear the storm. The captain followed the recommendation, protecting the vessel, crew and approximately 2700 containers on board. And even though the route along 32 degrees north latitude added approximately 80 nautical miles to the voyage, the Captain was able to maintain a much higher speed over this portion of the voyage and was able to arrive four hours earlier than the route along 35 degrees north latitude.