VESSEL REVIEW | Energy Craft 3514-01 – Fast crewboat trio to support West Africa oil and gas operations

Singaporean shipyard Strategic Marine has delivered new aluminium-hulled surface effect ship (SES) crewboats to Monaco-based operator All Energies Services (AES).

The Bureau Veritas-classed, 35-metre (110-foot) long Energy Craft 3514-01, Energy Craft 3514-02, and Energy Craft 3514-03 were designed in collaboration with French marine engineering firm Aircat Vessels and Norway’s Espeland and Skomedal Naval Architects (ESNA) specifically for offshore crew transfer operations. The overall layout of each vessel has been designed to simplify maintenance and minimise downtime.

“The design was specifically developed to meet and exceed the demands of the oil and gas industry,” Jerome Arnold, Managing Director at Aircat Vessels, told Baird Maritime. “Not only does it address critical operational requirements, it also provides enhanced capabilities that go beyond industry standards, offering improved efficiency, safety, and versatility in challenging offshore environments.”

With a reinforced hull and SES active motion dampening technology, each crewboat was designed to ensure safe and efficient transfers even in sea states characterised by wave heights of up to 2.5 metres (8.2 feet). By utilising a network of sensors and computer-controlled air dampers, the vessel dynamically adjusts to changing sea conditions, optimising both efficiency and comfort at high speeds. This advanced system ensures real-time adaptation to the marine environment for superior performance.

Innovative SES design promising greater efficiency

The vessels are each equipped with an air cushion system, which not only enhances stability and manoeuvrability but also significantly reduces fuel consumption by decreasing drag. Arnold said this makes it safer, efficient, and environmentally friendly, as this also translates into reduced emissions.

A motion control system, controlled by a motion reference unit, uses the air cushion to absorb the effects of swell. This prevents vertical motions, reduces vertical acceleration, and ensures users can safely access boats landing on FPSOs, offering enhanced safety during passenger transfers.

The cabin is equipped with business-class seating, offering enhanced comfort with reclining seats and leg rests. There is also an onboard entertainment system and a high-speed internet connection for passengers and crew.

Four MTU 16V2000M72 engines designed for continuous operation at high speeds drive Kongsberg waterjets, which are capable of rapid acceleration as well as less susceptible to damage from underwater debris. The propulsion arrangement enables each crewboat to easily reach speeds in excess of 50 knots to allow for quick transits even over long distances, which Arnold said is a critical factor for offshore operations.

The high operating speeds mean travel times can be reduced by almost half, allowing for same-day crew changes as well as more efficient management of human resources and operations. This in turn leads to the elimination of indirect costs such as those for additional hotel stays, associated ground logistics, and man-hours lost to overlap.

“This ability to cover the same distance in less time means fuel consumption is required for a shorter duration, resulting in a lower overall carbon footprint,” said Arnold. “This innovative concept not only enhances operational efficiency but also minimises environmental impact, offering a high-performance and sustainable solution for the offshore sector.”

The engines are arranged in a staggered configuration rather than side by side to optimise the space within the hulls. Due to the significant distance between the forward engine and the waterjet, Aircat Vessels opted for a carbon shaft.

Designed with crew and passengers’ well-being in mind, each crewboat offers excellent seakeeping capabilities, reducing motion sickness and ensuring smooth rides even in challenging sea conditions. The layout can also be tailored to specific operational needs, from seating arrangements to additional equipment integration, ensuring flexibility for various missions.

Designed with operators in mind

“We envisioned what the most appropriate vessel would be to meet offshore operational needs while also creating a vessel that we deem as ideal if we were to operate it ourselves,” Arnold told Baird Maritime. “This approach is reflected in the choice of equipment, as nothing was left to chance. We selected only premium, proven, reliable, robust, and high-precision solutions.”

He added that the vessels’ specifications were presented to the charterer, which recognised the benefits of such a design.

“After thoroughly evaluating the vessel and understanding its advantages, the charterer was convinced and formalised these specifications in a tender, which enabled us to offer these vessels in partnership with owner AES.”

As the crewboats were the first vessels in a new series, some complexities became inevitable, as Arnold explained.

“The first unit in a series often involves extensive trialing, testing, and adjustments, and we had a very limited timeline to meet the initial delivery and operational requirements. The design process was also highly intensive, as it was crucial to get everything right from the beginning.”

As the crewboats were among the first SES vessels to operate in the oil and gas sector, Aircat Vessels had to ensure that the design was optimised for both performance and safety. This meant guaranteeing that the air cushion system would provide the necessary stability and speed, all while working within tight deadlines for delivery.

There were also numerous testing phases, including sea trials to assess speed, stability, and overall performance in real-world conditions. Each of these tests provided the designer with new data and feedback, which then required iterative improvements. Balancing the need for thorough testing while meeting project deadlines thus became a crucial challenge.

“The collaboration between Aircat Vessels, ESNA, and Strategic Marine was key to overcoming the challenge” said Arnold. “With the pressure of a limited timeline, we had to ensure all teams worked together seamlessly to deliver the final product.

“Communication and coordination had to be flawless to ensure that each phase of the project, from design to construction to sea trials, was completed on time. In the end, these challenges were met with innovation, teamwork, and dedication, and the vessel is now ready to deliver exceptional performance in the oil and gas sector.”

Among the insights Aircat Vessels gained from working on AES’ new crewboats was determining ideal engineering solutions to address vibration during fast transits.

“With the extreme speeds achieved by the crewboat exceeding 50 knots, the vessel would naturally generate more pronounced vibrations as compared to traditional similar vessels going at half the speed,” said Arnold. “Therefore, advanced engineering – which was applied and successfully tested to mitigate these vibrations – proved to be highly transferrable to future high-speed vessels.”

Arnold added that Strategic Marine had long been building and delivering high-speed vessels for various applications and therefore has extensive experience in minimising vibration and noise on board, thus making the company the ideal shipyard for the AES crewboat project.

AES’ new crewboats will be operated off Angola, where it will ensure safe transfers of personnel to and from the offshore installations operated by TotalEnergies.

With secondary emergency response functions

“The vessels will perform round trips departing from Luanda, with the capacity to cover distances of up to 300 nautical miles in a single operation,” said Arnold. “They are equipped to transport urgent cargo on the forward deck, ensuring the rapid delivery of essential supplies to offshore installations. Additionally, the vessels can remain on standby to provide immediate response in the event of an emergency requiring medical evacuation, ensuring the safety and well-being of crewmembers and offshore personnel.”

Arnold said that, In emergency scenarios, the crewboats play a critical role by being capable of evacuating the entire workforce from an offshore installation quickly and efficiently. This versatility, combined with their high-speed performance and robust design, makes the crewboats indispensable for offshore operations in Angola’s demanding marine environment.

“Although primarily designed as crewboats, the vessels are also capable of carrying up to five tonnes of cargo on their forward decks,” Arnold told Baird Maritime. “Each crewboat’s deck is equipped with lashing points for securing cargo and is sized to accommodate a personnel transfer device or potentially receive an injured person on a stretcher.

“The design also features a dedicated rescue area equipped with a davit system for efficient man overboard recovery. It is also equipped with an external gas detector and a high-sensitivity thermal camera for heat detection and search and rescue (SAR) operations. Additionally, the vessel is fitted with an external deluge system designed to provide protection when evacuating personnel from offshore installations.”

Redundancy for greater safety

The crewboat boasts a high degree of redundancy to ensure that no engine failure requires a full stop of operations. Even in the event of a failure, the vessel maintains high performance with minimal speed loss, allowing each mission to continue without interruption. This feature is made possible by the redundancy of key systems, ensuring continuous service under all circumstances.

The air cushion system itself features multiple redundant components, including several pressure sensors, lift fans, bag fans, and a bow rubber skirt, which is divided into independent "finger sections." The electrical supply is supported by two independent Cummins Onan generators, though a single generator is enough to supply the vessel's total power requirements.

To ensure proper engine protection, the vessel is equipped with two highly efficient fuel treatment stations, each capable of providing more than enough fuel for the vessel's total consumption.

“In addition to the standard navigation system required by the High-Speed Craft Code, we have enhanced the vessel's safety with the integration of the SEA.AI Sentry anti-collision system,” said Arnold. “This system is equipped with multiple thermal and RGB sensors for surface object detection, improving situational awareness. Using AI learning, it provides the crew with information about approaching objects that may not be detected by other instruments.”

Another essential characteristic of the crewboats is their "plug and play" design. This concept allows for the rapid replacement of any main component, with extremely short downtime. This significantly minimizes operational downtime and helps maintain productivity and efficiency, even during maintenance or repairs.

“This combination of redundancy and ease of component replacement ensures optimal vessel availability for the owner, while reducing costs and unplanned interruptions,” Arnold told Baird Maritime.