RT Raven, First of Robert Allan Ltd.’s ART 100-46 Rotortug® DP2 Infield Support Vessel Design

February 7, 2018

The first of Robert Allan Ltd.’s innovative ART 100-46 Infield Support Vessel (ISV) design was recently named RT Raven at a ceremony at the Builder’s yard in Sharjah, UAE. This revolutionary vessel was designed by Robert Allan Ltd. in close collaboration with Rotortug B.V., Owners KOTUG Group, and vessel managers KT Maritime (joint venture of KOTUG International and Teekay Australia). The naming ceremony of the RT Raven was combined with the tug christening by long standing ConocoPhillips Australia employee Chantelle Birtwistle; currently the JV Manager for the Bayu Undan Project.

The RT Raven represents a number of “firsts” in Rotortug® history:

  • Largest Rotortug® built to date
  • First Rotortug® to have an anchor handling notation
  • First Rotortug® to have Dynamic Positioning capability (DP2)
  • First Rotortug® with an aft centreline skeg

The unique arrangement of the aft centreline skeg was arrived at after a comprehensive model testing and CFD program where significant effort was spent on finding the optimal appendage configuration for the best balance of the competing attributes of course stability, manoeuvrability, side stepping speed, and resistance. In the end, an aft centreline skeg was selected to be fitted which previously had never been done on a Rotortug®. This created a challenge as a Rotortug’s aft Z-drive is located in the same location. However, in cooperation with Z-drive supplier Schottel, a suitable arrangement was arrived at whereby a customized thruster with extended leg length would be supplied in order for the aft Z-drive propeller and nozzle to extend underneath the skeg. Adding a single tunnel thruster through the skeg then allowed for the DP2 capability to be achieved relatively easily.

Key particulars of the RT Raven are as follows:

  • Length: 46 m
  • Beam: 16.00 m
  • Depth (Least Moulded): 6.80 m
  • Draft Max: 7.00 m
  • GT: 1246
  • Aft cargo area: 190 m2
  • Total Deadweight Capacity: 890 tonnes
  • Bollard Pull: 100 tonnes

The aft deck features a waterfall winch with both steel wire and synthetic ship-handling towline, a retractable 800 mm diameter towing staple, Kooiman Delta Pins and fork, a stern roller, two tugger winches, two capstans, cargo rails, and a deck crane. The fore deck features a split drum ship-handling and tanker pull-back winch.

The vessel was constructed by Albwardy Damen and will have the following Bureau Veritas Class granted notation:


The RT Raven is capable of wide variety of missions including:

  • Escorting, berthing and unberthing operations (working off either the bow or the stern)
  • Tanker pull-back operations
  • Anchor handling
  • Floating hose handling operations and hose maintenance operations
  • Subsea support activities
  • Fi-Fi Class 1 capability
  • Pilot transfer
  • Security activities
  • Rescue and emergency evacuation capability

Preliminary yard sea trials are in progress and initial feedback on the performance of the vessel is excellent. The inventive RT Raven ISV will be an impressive addition to the KOTUG fleet and promises to further enhance the safety and efficiency of offshore oil and gas facilities support when she is deployed at ConocoPhillips’ Bayu Undan field in the Timor Sea.

For more information on the ART 100-46 tugs, or any other high-performance vessel designs developed by Robert Allan Ltd., please contact design@ral.ca.