Twin Screw Tug

The twin screw tug is still widely employed in many major ports and in deep sea world wide towage due to its excellent sea keeping qualities and fuel economy despite the introduction in recent years of ASD and ADT tugs of ever increasing power together with Voith Schneider Tractor tugs. Nothing yet has been designed to displace it from the market. 

 

Twin screw consists of two separate engines operating twin propeller shafts through gearboxes. The units can increase their manoeuvrability by fitting steerable nozzle units in place of skeg rudders. Both engines are controlled from the bridge often with the flexibility of controls for both engines being both combined and separate and being placed in consols on each side of the wheelhouse / bridge wings giving maximum the Tug Master both good visability and control when manoeuvring. These are often supplemented by bow thrusters (Combi Tug) and with the ability for one engine to put ahead and the other astern gives the twin screw tug the ability to react quickly to position changes and operate more successfully in confined areas. 

 

Twin screw tugs are usually often referred to as “conventional” tugs i.e.meaning a well proven design. Twin screw tugs of good power and designed for both harbour and coastal use were built in yards in the Northern Hemisphere up until the mid eighties and continue to be built today for the coastal market. 

Both the British and certain foreign navies have a known preference for twin screw multi role vessels. 

 

In the deep sea market ever larger twin screw tugs having in excess of 100 bollard pull have been built for multi role use. An example of this is the ETV (emergency towing vessel), built on the recommendation of Lord Donaldson after the Braer disaster. ETV vessels have been introduced globally in the last few years for employment to Maritime Authorities. Around the United Kingdom coast there are 4 deployed on long term hire to the Maritime and Coastguard Agency. 

 

In the medium power (2 to 4,000kW) a Portugese owner had sufficient confidence in 2002, to add to their fleet a twin screw tug of 50 tons bollard pull. 

 

Good quality second hand twin screw tugs of almost any bollard pull are eagerly sought by buyers and rarely remain unsold for long when they come on to the market.