Did You Know?
How does the difference in density between fresh water and salt water impact ocean transportation?
Saltwater is more dense than freshwater. For example, the density of freshwater in the Mississippi River in southern Louisiana is 0.999. The density of saltwater at Japanese ports is 1.025. Due to the more dense/heavier water in Japan, the vessel will automatically rise about 11.4 inches (29 centimeters). This explains one of the reasons saltwater ports are less susceptible to draft restrictions than freshwater ports. Ships do not sink as much in saltwater.
In addition, a typical Panamax ocean vessel consumes approximately 30 tons of fuel per day. If a journey from southern Louisiana to Japan requires 30 days, a ship will consume 900 tons of fuel. On a Panamax vessel, it takes approximately 66 tons to sink the vessel 1 centimeter (0.39 inches). Therefore, a vessel traveling from Southern Louisiana to Japan will rise in the water 5.35 inches (13.6 centimeters) due to utilizing 900 tons of fuel.
Therefore, a Panamax ocean vessel can have a reduction in draft requirements of 16.75 inches by traveling from southern Louisiana to Japan.
Draft – vertical distance between a ship's waterline and the lowest point of its keel. Depth of water to which a ship sinks according to its load. Most ships have parallel horizontal lines drawn on both sides of the bow (front) and stern (back) to indicate each foot of draft. |