Weather has a very significant effect on the maritime industry. Vessels encountering heavy weather will experience speed reduction due to increased resistance from wind and waves. In addition, heavy weather increases the risk to crew safety as well as for damage from excessive ship motion, slamming or seas washing over the decks. When ships enter gale force or higher wind fields the ability for the master to maneuver the vessel becomes significantly affected, thus reducing route options.
Optimum ship routing is the art and science of developing the “best route” for a ship based on the existing weather forecasts, ship characteristics, and cargo requirements. For most transits this will mean the minimum transit time that avoids significant risk to the vessel, crew and cargo. The goal is not to avoid all adverse weather but to find the best balance to minimize time of transit and fuel consumption without placing the vessel at risk to weather damage or crew injury. The routing goal may not always be to reduce the time of transit. Sometimes the goal will be to reduce fuel consumption or to keep a vessel on a regular schedule.
Route planning normally will start by reviewing the appropriate Pilot Chart Atlases and Sailing Directions (Planning Guides) to determine the normal weather patterns, weather risks and prevailing ocean currents. The routing service then reviews recent weather patterns and weather forecast charts to determine the most likely conditions during the course to the voyage and what route options there might be.
North Atlantic Pilot Chart
A preliminary routing message is transmitted to the master of a vessel prior to departure with a detailed forecast of expected storm tracks, an initial route proposal with reasoning behind the recommendation and also the expected weather conditions to be encountered along that route. Sometimes alternate route options may be offered based on various forecast scenarios. This allows the master to better plan his route and offers an opportunity to communicate with the service any special concerns that he or she might have due to special cargo requirements or ship condition. Once the vessel departs, the vessel’s progress is monitored closely with weather and route updates sent as needed.
The benefits of optimum ship weather routing is primarily in reducing operating costs, increasing the safety of the crew and minimizing risk for damage to the vessel and cargo. The savings in operational cost come about by reducing transit times, fuel consumption and cargo and hull damage as well as more efficient scheduling of dockside activities. Additional savings come from increasing the service life of the vessel and reduced insurance costs.
Various studies have shown that optimum ship routing savings in time and fuel range from 2-4% to as much as 8-10% depending on the type of vessel, season and ocean. On average savings should run between 4-8%. Given and average savings of 4% and a bunker price of about $600/ton, a ship burning 50 tons of fuel per day would see savings of over $8000 on fuel costs alone during a 7 day transit, not to mention the savings in transit time.