SEACOR MARINE'S NEW CrewZer Class of vessel, complemented by a purpose-built transfer solution in the form of Reflex Marine’s nine-passenger Frog crew transfer device, was designed to provide a superior service, in terms of safety, speed and passenger comfort.One year of incident-free operation in West Africa, and around 30,000 passenger transfers, means it is arguably the industry’s safest crew supply option and a viable alternative helicopter transfer.
CrewZer Class vessel
The new CrewZer Class vessel is 50m long and has a very wide beam of 11.6m due to its catamaran design. Its spacious main deck (27.8m by 9.14m) was devised to provide an excellent area for landing and loading the transfer capsules, with landing areas provided at amidships or toward the aft, allowing flexibility to manage location specific variables, such as weather direction, crane reach and vessel motions.
Each of the two hulls is powered by 2 MTU 16V 4000 engines and the vessel achieved an impressive 42 knots during trials. The CrewZer is the fastest workboat ever built and even at economy speed is some 10–15 knots faster than most crew supply vessels. The vessel is highly manoeuverable with its four main water jets and each hull is fitted with a 200HP azimuthing bow thruster.
With a 149 passenger capacity and under 100 tons gross weight, It is one of very few crew/supply boats with a DP-2 rating. On arrival at the installation, the Kongsberg SDP21 dynamic positioning system takes over the navigation of the ship. This allows CrewZer to provide close position holding support for even deepwater floating rigs where movement of up to 30 m can be expected. Keeping manual control to hold station during crew transfer activities would be very tiring, but with full DP-2 rating the vessel is ideal for safe and efficient transfer operations. The ship is equipped with state-of-the-art electronics, communications and navigation systems. Image intensified night vision and day color camera equipment assists night time deployment of the vessel around rigs and platforms where unlit buoys are not detected on radar.
The 10-person crew is accommodated on the mid deck level and on the upper deck is a large fully equipped wheelhouse offering full 360° vision, with excellent visibility onto the aft deck. The vessel can carry 150 tonnes of cargo on a 251 sq m deck, as well as 60 cu m of cargo fuel. By combining a powerful crew supply capability with flexible and rapid cargo transit, it provides operators with a very attractive economic package. In the event of a fire on the host installation, the vessels speed allows rapid deployment for emergency support. It made sense that the vessel specification included a pair of remote-controlled fire monitors with a capacity of 24 cu m per minute.
Passenger comfort was viewed as a top priority, to gain increased industry acceptance for marine crew supply solutions. The passenger lounge on the main deck is laid out and equipped similarly to a wide bodied airliner, with a 3-6-3 seating format. The lounge features a pair of 107-cm LCD televisions, wireless internet and a beverage and snack area, helping to ensure that passengers are fresh and ready to work on arrival at the offshore platform. For travelling at speed, the vessel is fitted with a wave dampening system developed by VT Maritime Dynamics. The vessel automatically smoothes out the effect of any wave action and minimises the likelihood of travel sickness.
High capacity transfer device development
To fulfil the need for increased transfer rates, a range of device designs and configurations was assessed. Eventually a nine-passenger version of the industry-leading Frog crew transfer capsule was selected.
With safety as a top priority, the new high capacity devices were designed with ABS type approval. The new units were subjected to a rigorous test regime to verify the defined safe operating envelope. Reflex Marine’s approach to rigorous testing and verification are unique in the industry and set the products apart from competitive products.
In May 2008, the Seacor Cheetah CrewZer Class vessel began a three-year contract providing marine and crew transfer services to Sonangol, the National oil Company of Angola. For Sonangol’s operations, where passenger lists of 120 were routine, the operations were optimised by using two Frog-9 devices in tandem. One device was positioned on the installation, whilst the other was landed on the vessel. The vessel crew would then unhook the device on the vessel, allowing the crane to pick up the unit on the installation. Meanwhile, the device on the vessel would be unloaded and another batch of passengers loaded, ready for transfer to the installation. This cycle of tandem lifts would continue until all passenger transfers were completed. In effect, this approach removes all loading and unloading activity from the critical path.
The highest transfer rate achieved to date is 125 pax/hr when a total of 253 people movements took place in two hours. With more than 60,000 miles travelled and 21,000 transfers now completed in Angola, the new transfer solution has delivered an impressive safety performance with zero incidents. The vessel has also demonstrated its station-keeping capability in adverse sea conditions and is routinely required to maintain station at some five meters from the installations.
The system has been shown to offer a highly competitive alternative to helicopter crew supply, including achieving an estimated cost saving of around 30 per cent. In addition to providing the crew supply service previously performed by helicopter operators, the CrewZer solution has provided high quality logistical support to the operations. The service also provides important contingencies for fire fighting, emergency evacuations and MedEvac.
The collaboration of a vessel operator and transfer specialist has proven to be highly beneficial to all parties and it is envisaged that this collaboration will continue in order to enhance the capability, safety and transfer rate of vessels yet to be commissioned.
Authors: David Brittan, Reflex Marine Ltd; Steve Douglas, Seacor Marine LLC