The Netherlands-based Temporary Works Design (TWD) has introduced a Hammock monopile seafastening that is said to accommodate foundations with a diameter of up to 11 metres without any changes to the support structure.
The seafastening consists of two supports fixed to the deck of the vessel either transversally, across the vessel, or longitudinally, from bow to stern. One side of the support is fixed rigidly upright while the opposite side frame is hinged at the base. A specially designed rope is slung between the two sides in a cross-over pattern, designed to avoid lateral movement of the monopile.
When loading the monopile on to the vessel the hinged support frame is held open and, as the ropes take the weight of the monopile, this support automatically closes. Contact pads on the upper horizontal part of the frame will come to rest on the monopile securing the lateral support.
Stacking a second frame on top of the bottom support frame is possible, TWD said. The upper support frame is then equipped with a hydraulically operated lifting arm to raise the rope to one side to give access to the monopile below.
The whole seafastening uses less steel than conventional designs saving on cost and weight, according to TWD. Mobilization and demobilization time between projects will also be faster and easier.