Deepwater operations are producing new challenges for operators, as production platforms get larger, and are located fueurability, leading to longer installation times. ther from shore. These platforms are now close to the limit of helicopter range, introducing greater safety concerns and limiting the cargo weights that can be carried, while conventional Offshore Support Vessels travel slowly and would take several days to reach the platforms. Higher power requirements for anchor handling duties means more vessels and more cost, or larger vessels and lower manoeuvrability, leading to longer installation times. In addition proposed maritime legislation will reduce permitted NOx emissions to levels where post-combustion clean-up will be required on diesel engines, adding cost and requiring valuable space.
This paper examines potential solutions to these challenges using a novel design of all-electric ships using LNG as the fuel and the advantages offered over conventional solutions.
The concept Fast Sea Shuttle (FSS) is a high speed multi-purpose 95m vessel capable of operating at transit speeds of up to 40 knots while still carrying considerable cargo loads and enabling rapid personnel transport in relative comfort and safety compared to current methods, and can contribute to the reduction in overall costs of personnel transportation and logistics. The concept 100m AHTS design offers a bollard pull of 380 tonnes while remaining a compact, manoeuvrable vessel. Both vessels are expected to be able to operate in sea states of 4 - 5m thereby reducing waiting time for the weather and providing improved safety for the vessel and its crew.
In addition to novel design features, the key to the high speed of the FSS, and the high bollard pull and fast response time of the AHTS, is the use of an al-electric propulsion system, combining reciprocating engine and gas turbine generator sets for fuel efficiency, using clean-burning LNG as the main fuel. This concept, making use of the high power density and fast loading times f the gas turbines, provides the most efficient solution with reduced weight to maximise speed, towing power, load carrying capability and passenger comfort, while minimizing the environmental impact of logistical operations by using ‘clean’ natural gas.