Elsewhere we have made reference to shore cranes, operated by the local port authority, used to assist with the loading/discharge of vessels. In large part, most ports are well equipped, sometimes supplemented with floating cranes.
When Heavy Lift Vessels are needed
However, with some of the largest pieces, it may be impractical to deliver to one of the major ports – bringing into play smaller, local harbours, without the necessary facilities. This is where heavy lift vessels come in, equipped with their own ship’s derricks.
Types of Heavy Lift Vessel
At the lower end, there are conventional vessels, equipped with a relatively modest lift capacity. We can well remember in the early days a consignment from the UK to Ghana. Initial routeing was by road/ferry to Rotterdam, where the cargo (largest piece about 95 tons) was transferred to a waiting vessel. On arrival at Accra, ship’s derricks were brought into play, it being on the limit of their capacity. To the consternation of everyone, as the piece swung over the ship’s side, it started to list badly – thankfully the piece landed on the quay/trailer before the ship capsized!
On a more recent shipment, for delivery into the Conoco Refinery at Milford Haven, it was discovered that the quay was unable to support a mobile crane, plus the trailer, plus the piece – hence the reason for using a heavy lift vessel, eliminating the weight of the crane. However, the length of the quay and available draft then had some bearing on the vessel selection.