Editing Catamaran (section)

=== Resistance ===

At low to moderate speeds, a lightweight catamaran hull experiences resistance to passage through water that is approximately proportional to its speed. A displacement monohull has the same relationship at low speed since resistance is almost entirely due to surface friction. When boat speed increases and waves are generated the resistance is dependent on several design factors, particularly hull displacement to length and hull separation to length ratio, it is a non trivial resistance curve with many small peaks as wave trains at various speeds combine and cancel<ref>Principals of Naval Architecture SNAME</ref><ref name=Garrett/> For powered catamarans, this implies smaller power plants (although two are typically required). For sailing catamarans, [[Forces on sails#Reactive forces on sailing craft|low forward resistance]]<ref>{{ cite book | last1 = Yang | first1 = C. | last2 = Löhner | first2 = R. | last3 = Soto | first3 = O. | title = Practical Design of Ships and Other Floating Structures: Eighth International Symposium | place = China | publisher = Elsevier | volume = 1 | editor-last = Wu | editor-first = You-Sheng | editor2 = Guo-Jun Zhou | editor3 = Wei-Cheng Cui | chapter = Optimization of a wave-cancellation multihull using CFD tools  | date = August 22, 2001 | isbn = 9780080539355}}</ref> allows the sails to [[Forces on sails#Lift predominant .28attached flow.29|derive power from attached flow]],<ref name=Weitner>{{ cite journal | last = Weltner | first = Klaus | title = A comparison of explanations of the aerodynamic lifting force | journal = American Journal of Physics | volume = 55 | issue = 1 | pages = 52 | date = January 1987 | doi = 10.1119/1.14960 | bibcode = 1987AmJPh..55...50W }}</ref> their most efficient mode—analogous to a wing—leading to the use of [[wingsail]]s in racing craft.<ref name=Sail>{{ cite magazine | last = Nielsen | first =  Peter  | title = Have Wingsails Gone Mainstream? | magazine = Sail Magazine | publisher = Interlink Media | date = May 14, 2014 | url = http://www.sailmagazine.com/boats/have-wingsails-gone-mainstream | access-date = 2015-01-24 }}</ref>