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Think Twice
About Load Line Restrictions!

It is that time of year again.

StormGeo Shipping Insights, October 2013
By George Schlinkert, Vice President of Operations

Load line restrictions are removed in the southern hemisphere, and go into force in the northern hemisphere.


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Northern Hemisphere Load Lines.

Loading additional cargo can be tempting, but one must be fully cognizant of the consequences. The following wave rose shows the likelihood of wave height and direction at the southern limit of the winter load line zone in the north Pacific at mid-ocean. A close examination reveals that waves are almost invariably from the west, putting them on the head of a westbound vessel. When westerly waves are prevailing, waves of four meters or less exist about 20% - 25% of the time; however waves of five meters or greater may exist in excess of 75% of the time. Waves are not always from the west; however, they are the predominant direction.


When trying to calculate the optimal loading condition, the great circle route must be disregarded. In the following image, the great circle route exits the Seasonal Tropical Zone south of Baja California; however, the ship then would encounter storm winds with waves in excess of 10 meters across the central ocean. On a more southerly route, the severe weather can be avoided and earlier arrival achieved despite the longer distance.

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Two route options shown in BVS factoring load lines and weather conditions.

As an additional benefit, the vessel can spend almost 11 additional days in the tropical zone. For a ship consuming 30 MT/day the vessel can carry an additional 330 MT of cargo at no cost. Finding the optimal amount of cargo however can vary depending on departure port, arrival port, and other factors such as the ship's actual speed and consumption.

Of course, the summer load line comes into play on many other trade routes. In the following example, a client requested StormGeo service after loading 1,000 MT of extra cargo, and with it the obligation to sail within the summer zone. While a direct route was envisioned, the ship needed to deviate to Hawaii for additional bunkers owing to the severity of the conditions encountered, and the southerly route added more than 10 days to the process.

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StormGeo can help avoid the above situation by working closely with the ship operator to determine the optimal route. Given seasonal load line restrictions, it is our goal to assist operators so they can maximize their profits.