Innovation and Diversity

in Marine Design

Case Studies: Major Design and Consulting Projects

We are proud to highlight recent significant projects that illustrate the ways in which our creative design and engineering services have been applied to address unique operational challenges for our clients.

Innovative design concepts and technical analysis can improve vessel efficiency, transportation economy, and transportation system safety.


Shell is currently (2015) building the Prelude Project, the world’s first floating liquefied natural gas (FLNG) project, which has the potential to revolutionize the way in which natural gas resources are developed. It will be, when installed, the world’s largest offshore installation.

Robert Allan Ltd. were contracted directly by Shell to evaluate and define the best type of tugboats required to provide escort, ship-handling and standby duties at the Prelude site for the safe operation of the large gas carriers envisaged.

Robert Allan Ltd. conducted analyses of the forces involved in all aspects of the service, and then prepared a concept design for the type of tug recommended, a 40 metre fire-fighting ASD type escort tug with 100 tonnes BP, and facilities for accommodating a large number of rescuees.

This basic design concept was used as the basis of soliciting service proposals from tug operators worldwide, with the option of offering variants on the concept. The successful proponent was Kotug of the Netherlands who submitted a triple drive ART 110-42 Rotor Tug™ variant, also developed by Robert Allan Ltd.

The scope of services included extensive model testing to verify all aspects of tug performance, the preparation of all typical design drawings and specifications required for Class Approvals and shipyard bidding, studies of the tug motions for maximum crew comfort under extended periods at sea, and an economic analysis of the most effective mode of tug operations under extended loitering conditions.

Two tugs to this very unique design are presently under construction.


In 2013, Robert Allan Ltd. was contracted by Enbridge to provide consulting services regarding the identification of all elements of the support fleet of tugboats and pollution response vessels necessary for the safe transport of oil by tanker through the coastal transportation sector of the proposed Northern Gateway Pipeline project.

Initial studies were conducted to establish the required levels of escort and ship-handling forces at all critical points along the intended routes, and then detailed simulations were performed to establish which of various types of large escort tugs could best provide those forces and exercise the most effective control over a potentially disabled tanker in these sensitive waters. Similar studies were conducted to identify and define the best combination of ship-handling tugs to perform the required duties at the terminal. Robert Allan Ltd. then prepared extensive preliminary design drawings and specifications defining all the required tugs.

Similarly, preliminary designs were developed to define a complete fleet of emergency spill response and recovery vessels, including oil recovery vessels, support craft, and large oil recovery barges. Detailed CAPEX and OPEX estimates were prepared for the entire fleet.

The major outcome of the project was the definition of the proposed 50 metre long RAincoast Guardian class of escort Rotor™ Tug, which would be the largest and most powerful tug of its class in the world, capable of generating 200 tonnes of indirect steering force and capable of performing an ocean rescue of the largest tanker envisaged within this system, in extreme sea and weather conditions.



For a number of clients, over a period of about 3 years, Robert Allan Ltd. studied the requirements for large shallow-draft river tugs to enable the transportation of 50,000 tonne convoys of barges carrying iron ore from Brazil’s Corumba mine to tidewater in the vicinity of Buenos Aires.

A major challenge of this project was proving the safe transit and steering of the convoys when running laden downstream in the strong currents. Using extensive CFD analysis, Robert Allan Ltd. engineers were able to clearly demonstrate that carefully-designed shallow-draft tugs equipped with multiple Z-drive propulsion systems could meet all the required performance criteria established by the Brazilian Authorities.


After numerous iterations, and with the proof of performance assured by the CFD analysis, the project for supply of the tugs and associated barges was finally awarded to Hidrovias do Brazil, who retained Robert Allan Ltd. to develop the detailed designs for a series of 8 large pusher tugs and a flotilla of 150 hopper barges.

The vessels were delivered to the waterway throughout 2014 and have since been proven to be extremely effective in service, outperforming many previous vessels on the Rio Parana/Rio Paraguay river systems.



Not all our projects involve the design of major floating equipment. Often we are called upon to provide technical expertise to the legal fraternity or to various regulatory authorities in diagnosing the cause of a vessel incident or loss, or an on-board mechanical failure. An extreme example of such a review was a contract with WorkSafe BC to analyze the sinking of the fishing vessel “Cap Rouge” with the attendant loss of several lives. This study entailed taking a complete laser-scanned model of the hull and compartments in order to establish the hydrostatics and capacities of the hull, and then, based on the evidence available, examining the impact on the boat’s stability of every single potential causative factor. The result was very telling as to the root cause of the catastrophe, and ultimately became the subject of a number of technical papers.


Impact on GZ Curves


Effects of the Towed Skiff

Browse our Design Portfolio or read through The Company to learn more about Robert Allan Ltd. and our record of diverse and innovative designs.