The Carrousel RAVE Tug

Dutch towing group Muller Maritime has taken delivery of the harbor/escort tug Multratug 32. Despite the long number in its name, it is both the first in its class and the first vessel of its kind.

Designer Robert Allan Ltd. calls it a “Carrousel RAVE Tug,” or CRT, and it integrates two features into a novel new package. First, it has two Voith cycloidial drives arranged fore and aft (the Robert Allan-Voith RAVE design).

Second, its towing winch is mounted on a giant circular bearing – the “Carrousel Towing System” – which sits around the entire wheelhouse. With these design elements the tug can rotate with a load on its line, without fouling the towline on its own superstructure or girting. It is designed to pivot relative to its direction of travel, creating drag with the width of its hull.

Robert Allan says that it is the tug’s relative heading that determines the magnitude of the towline force. At speed, large forces can be generated by applying a small amount of thrust to change the tug’s orientation to the escorted vessel. The propulsion system is primarily used to control the tug’s heading, position and speed – not to generate bollard pull.