sea-lane

Modern shipping lanes

A sea lane is regularly used route for ocean-going and Great Lakes vessels. In the time of sailing ships they were not only determined by the distribution of land masses but also the prevailing winds, whose discovery was crucial for the success of long voyages. Sea lanes are very important for trade by sea.

History

The westerlies and trade winds

The ocean currents

Shipping lanes came to be by analysing the prevailing winds. It is well known that the trade winds allowed ships to sail towards the west quickly, and that the westerlies allowed ships to travel to the east quickly. As such, the sea lanes are mostly chosen to take full advantage of these winds. Currents are also similarly followed as well, which also gives an advantage to the vessel.

It should be noted however, that the sea lanes were chosen based on the importance of cities as well, which could explain some anomalies towards the currents/winds, such as the fact that the shipping lanes are not optimally chosen for the route from Cape town towards Rio de Janeiro (passing Tristan da Cunha).

As they were very important lanes, they were popular places for pirates.

In World War I as German U-boats began hitting American and British shipping, the Allied trade vessels began to move out of the sea lanes to be escorted by Naval ships.

Advantages

Although most ships no longer use sails (having switched them for engines), the wind still creates waves, heeling. As such following the overall direction of the trade winds and westerlies is still very useful. However, any vessel that is not engaged in trading, or is smaller than a certain length, is best to avoid the lanes. This is, not only because a (slight) collision with a large ship can easily cause a smaller ship to sink, but also because large vessels are much less manoeuvrable than smaller ships, and need much more depth. Smaller ships can thus easily take courses that are nearer to the shore. As (unlike with road traffic), there is no exact "road" a ship must follow, this can easily be done.

Shipping lanes are the most busy parts of the sea, thus being a useful place to visit when your boat is damaged and is on the virge of sinking, or to boat to with a liferaft. However, if the boat sinks near to shore, it is of course safer to head in that direction instead.

Declining importance

The lanes will probably lose in importance as hydrofoils/low friction hulls do their entrance into boating. Also, the advantage of the wind direction will also reduce in importance as new sail designs are being used as rotor ships and windmill ships (hereby no longer requiring that the wind comes from an angle of 180° to 90° to the ship for fast boating.

Threats from shipping lanes

Aldough the shipping lanes are useful, they do pose threats to some people.

• Divers should stay clear of shipping lanes when performing dives.
• Small vessels also do best to avoid the lanes.
• As the shipping lanes are very large, sections of the lane exist which can be shallow or have some kind of obstruction (e.g. sand bank). This threat is greatest when passing some narrows, such as between islands in the indian ocean (e.g. near Indonesia) as well as between islands in the Pacific (e.g. near the Marquesas islands, Tahiti)

See also

• Age of sail