THE PORT OF LONDON AUTHORITY (PLA) provides marine patrols for the safety of other river users. Traditional patrol and rescue craft designs, whether of semi-displacement or planning hull form, including rigid inflatable boats, create substantial wash when moving at high speed, for example when responding to an emergency. Indeed, it is not unknown for rowers and others in small boats to be caused substantial distress by a rescue craft passing at high speed. Large wash created at speed may also be damaging to the riverbank environment, and the high resistance created by the wash waves causes high fuel consumption and creates unnecessarily high atmospheric emissions.
The PLA commissioned theoretical and practical studies to optimise the design for a replacement class of safety patrol launch. Southampton’s School of Engineering Sciences, was contacted to determine the wash characteristics of existing and contending designs. Subsequent research of the best performing hull, Ecocats, was fine-tuned by the boat-builder’s naval architect. Southampton provided expertise in computational modelling of the catamaran designs and the subsequent testing of the hull at model scale. Following these trials Ecocats, PLA and Southampton determined the combination of ship trim and displacement that gave the optimised resistance of the craft together with the reduced wash.
The effect of the successful delivery to PLA of the Ecocats catamarans has meant that Ecocats is now exploring the expansion of its shipyard. The technological innovation has allowed the service speed of these vessels to exceed those of the original craft at a reduction of wash, and erosion of the banks of the Thames has been reduced. The first of class, Chelsea, is now in service in the PLA’s upper district. The vessels have an increased operational platform, are flexible for a variety of tasks, and will carry all equipment and resources required for duty, yet they have displacement of less than half the previous craft.
For more information visit www.soton.ac.uk/ses and www.ecocats.com