High Speed Catamaran Hull Development
• BMT have a large range of high speed monohull and catamaran designs
• In order to meet client requirements for good levels of comfort in rough water conditions, the company has developed new hybrid catamaran / SWATH (Small Waterplane Area Twin Hull) designs that offer significant improvement in vessel motions in higher sea states.
• Hull development was initiated by extensive work undertaken for USN on Seafighter project
High Speed Catamaran Hull Development
Conventional High Speed Catamaran
• Low power requirement
• Moderate seakeeping capability
• Can be susceptible to uncomfortable pitch, roll and couple pitch and roll motions
SWATH
• Excellent Seakeeping Capability achieved by small waterplane area that reduces response of vessel to wave motions
• High power requirement
• Limited speed capability
High Speed Catamaran Hull Development
MODCAT – Hybrid Semi-SWATH Catamaran Design Developed for USN to offer improverd motions in rough sea states developed by BMT Nigel Gee.
• Motions (~50% reduction)
• Powering – small power increase in calm water
• Power saving in rough water / Reduced speed loss in waves
High Speed Catamaran Hull Development
• New eXtreme Semi-Swath (XSS) hull form design combines the benefits of Swath hull forms and catamarans
• Very good motions in rough sea conditions through SWATH type low waterplane area hull form in conjunction with high speed Ride Control System (RCS) using T-Foil and interceptor.
• Higher power than Modcat hull form but offering outstanding motions for reduced seasickness / increased passenger comfort
• Easy maintenance of main engines and waterjet propulsion
High Speed Craft - What Goes Where ?• The following looks at the performance benefits of different catamaran hull form
designs for high speed operation.
MODCAT (Semi-SWATH Catamaran)
• Slight increase in powering over catamaran
• Improved seakeeping
• Good for high speed ops on rougher routes
XSS (extreme Semi-SWATH catamaran)
• Higher fuel use / more limitation in speed over cat’
• Exceptional seakeeping
• Good for med’ to high speed ops on rough routes
Catamaran
• Good efficiency/ fuel use
• Good seakeeping
• Good for high speed ops on reasonably sheltered routes