FULL-SCALE MEASUREMENTS AND IMPACT STUDIES WITH HIGH SPEED FOIL-ASSISTED CATAMARANS IN A WAKE SENSITIVE AREA

Surface waves generated by high speed ferries operating at trans-critical and super-critical speeds can potentially cause adverse impacts to shorelines in confined waterways and environmentally sensitive areas. Repeated attempts to establish passenger fast ferry service on the Seattle-Bremerton route in Puget Sound have met with limited success due to such impacts. Trans-critical speeds along this route vary with tidal state in the range of 26 to 36 knots. Furthermore, the critical hump speed of most commercial-scale passenger only vessels is in the range of 15 to 26 knots. In general, speeds between the critical hump speed and trans-critical depth range should be avoided to reduce the potential for beach impacts in this area. The extent to which this condition might constrain the future of high speed operations on the route is the subject of this paper. An experimental program was designed to test the application of a foil-assisted catamaran that exhibits high potential for commercial application in terms of both wakes and fuel efficiency. Results indicate a foil-assisted catamaran design optimized for low wake operations has potential to operate at trans-critical and super-critical speeds with significantly reduced impact compared with a conventional catamaran that formerly operated on the route.