Marine Link
Tuesday, October 25, 2016

Dutch Invention Prevents Towline Failure on Tugboats

May 30, 2012

The Rotterdam based shipping company Rotortug and ASD Ship Design from Alblasserdam have invented a revolutionary tugboat technology (‘tugnology’) to prevent towline failures from chafing against a tugboats fixed towing point.

Conventional towing point designs are usually fixed bitts fitted with polished and stainless steel cladding in line contact areas guiding a towline to a towing winch. Using state of the art towing winches, towlines are winched in and out automatically by using a pre‐set line force to prevent both dynamic overloads and slack wires. Synthetic towlines can easily fail due to chafing and friction with increased risks for safety.

Fast in‐ and outgoing movements of a towline with these winches cause high temperatures in especially the inner core of synthetic towlines. This is an even bigger issue at high outdoor temperatures. The fiction and the high result temperature cause much wear and, at the end, failure of a towline connection.

Rotortug and ASD Ship Design in co‐operation with the company Ridderinkhof in Hasselt have developed a rotating wheel construction to guide the towline without friction. ‘’Our azimuth friction free towing point will be of great influence to towing methods,’’ according to Mr. Ton Kooren of Rotortug. ‘’Especially when synthetic towlines are used our invention holds many advantages.’’ The patent on this invention is currently pending. Synthetic towlines are gradually replacing steel wire towlines. They are generally seven times lighter compared to equivalent steel wire towlines. In fact synthetic towlines are so light (and thus easy to handle) they float in water. A downside to synthetic towlines is their sensitivity to chafing and maximum safe working temperatures. Together with the Rotterdam based maritime service provider Kotug International and the Rotterdam pilot organization Rotortug has developed new methods to assist sea going ships.

One of these methods is the so called ‘rotoring’, a method through tugs of the Rotortug type can assist objects to be towed and moored in confined spaces. The azimuth friction free towing point enables ‘rotoring’ in heavy seas.

Rotortug bv develops, builds and sales tugs. The Rotterdam based company is known for its revolutionary tug concept Rotortug, featuring three azimuth thrusters which provide a greater maneuverability and better specific towing characteristics compared to conventional tugboat designs.

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