We have all seen speed limits in harbours, estuaries and rivers and have also seen what happens when those limits are ignored. The vessel breaking the speed limit cruises past seemingly totally unaware of the chaos breaking out behind in its wake. Moored boats jerk violently on their moorings, a small child nearly gets swamped in their Oppie and all on board your boat get a nasty splash as the wake crashes over your hull! Most inconvenient for all involved. However, there is possibly some more permanent and worrying damage being done on the banks of the river each and every time this occurs.
All banks and coastal habitats are adapted to deal with waves and natural erosion. Natural protection in the form of reed beds, salt marshes and other habitats can dissipate wave effects. However, boat wash becomes significant in water bodies where the wake generated is greater than the natural background wave conditions. Examples of those more vulnerable habitats include inland waterways and canals, steep un-vegetated banks, intertidal mudflats, fragmented saltmarsh, shallow waters and seagrass beds. The effects may include habitat destruction, habitat disturbance and species disturbance all of which have a negative effect on the local environment.
Considerate pilotage and good boat handling skills can considerably reduce both wake and propeller effects. For more information on the effects of wash and also to learn how to reduce noise whilst out on the water visit The Green Blue website.