Rainbowing

Rainbowing is the process in which a dredging ship propels sand that has been claimed from the ocean floor in a high arc to a particular location.

[2] During the excavation process, large quantities of water are collected along with sediment creating a mixture called slurry.

Smaller diameters, for instance, have less flow leading to lower hourly output, but are able to project the slurry over a further distance due to a higher exit velocity.

Jumbo dredgers today can easily achieve distances in excess of 150 metres, but at the cost of 30% extra discharge time.

[3] Since rainbowing transfers material by ejecting it through the air, the technique is useful for reclaiming areas that are too shallow for direct placement.

Throughout the dredging and nourishment process, plumes of fine sediment, which can take longer to settle, can remain suspended in the water for long periods of time.