Jib crane conserves marine life

Jib crane, jetty and boathouse.

A Condra jib crane installed on a small island off the South African coast is rendering sterling service to ornithological teams visiting and conserving marine bird colonies that nest and breed there.

Installed with a motorised 360° slew on Bird Island, 8km offshore from Woody Cape and 62km from Port Elizabeth, the jib crane has been used since 2010 to lift the scientists’ boat from the sea onto a trailer, which is then winched along the jetty into a boathouse for the duration of the visit.

The scientific visits are important for the study and restoration of the island’s marine bird colonies.

Protected by South African National Parks as part of the Addo Elephant National Park, Bird Island and several smaller rocky outcrops form important habitats for bird life. The 2.4ha of Bird Island itself are home to South Africa’s greatest colonies of Cape gannets (65,000 breeding pairs,) African penguins, endangered roseate terns (just 250 breeding pairs,) Antarctic terns and kelp gulls.

Success stories include the revival of the island’s population of African penguins from fewer than 100 pairs 75 years ago to well over 10,000 birds today, the result of the cessation of guano scraping and the extermination of feral rabbits.

To meet the requirements of the visiting scientific teams, H&M Cranes of Port Elizabeth supplied a Condra jib crane with a 360° slew and reach of 4,5m, fitted with a single-speed 2.5 ton chain hoist with a 7,5m lift. H&M Cranes is the Port Elizabeth agent for Condra products.

Although the jib crane came from Condra’s standard range, its components had to be designed in four sections each having a mass under 800kg, to allow transport and installation on the island by helicopter.

An Alouette helicopter hired by National Parks was used to ferry the crane components to the island in three trips, with a fourth journey being made to bring in the jib.

The lower two sections of the column were mounted on the foundation plinth of an underwater concrete foundation, bolted together and encased with concrete. The top column section, jib and motor were then installed with the aid of the Alouette, which precisely positioned the motor for fitting and attaching.

Gauteng-based Condra offers a range of standard jib cranes with capacities of up to five tons and reaches up to 7m. These standard designs provide the company with a competitive advantage when short lead times are specified, because most South African crane manufacturers lack a standard range.

Condra has also supplied custom designed jib cranes with reaches up to 12m.

The company is currently manufacturing a standard five-ton jib crane for Grootegeluk coal mine in Lephalale.