Editing Rogue wave (section)

==Design standards==

In November 1997, the [[International Maritime Organization]] (IMO) adopted new rules covering survivability and structural requirements for bulk carriers of {{convert|150|m|ft|abbr=on}} and upwards. The bulkhead and double bottom must be strong enough to allow the ship to survive flooding in hold one unless loading is restricted.<ref>{{cite web
 |title=Improving the safety of bulk carriers
 |publisher=IMO
 |url=http://www.imo.org/includes/blastDataOnly.asp/data_id%3D6609/BULK.PDF
 |archive-url=http://arquivo.pt/wayback/20090707145541/http://www.imo.org/includes/blastDataOnly.asp/data_id%3D6609/BULK.PDF
 |url-status=dead
 |archive-date=2009-07-07
 |access-date=2009-08-11
}}</ref>

Rogue waves present considerable danger for several reasons: they are rare, unpredictable, may appear suddenly or without warning, and can impact with tremendous force. A {{convert|12|m|adj=on|abbr=on}} wave in the usual "linear" model would have a breaking force of {{convert|6|MT/m2|psi|abbr=~}}. Although modern ships are typically designed to tolerate a breaking wave of 15 t/m<sup>2</sup>, a rogue wave can dwarf both of these figures with a breaking force far exceeding 100 t/m<sup>2</sup>.<ref name="skuld" /> Smith presented calculations using the International Association of Classification Societies (IACS) Common Structural Rules <!-- (CSR) --> for a typical bulk carrier.{{efn|Smith has presented calculations for a hypothetical bulk carrier with a length of 275 m and a displacement of 161,000 metric tons where the design hydrostatic pressure 8.75 m below the waterline would be {{nowrap|88 kN/m<sup>2</sup>}} ({{nowrap|8.9 t/m<sup>2</sup>}}). For the same carrier the design hydrodynamic pressure would be {{nowrap|122 kN/m<sup>2</sup>}} ({{nowrap|12.44 t/m<sup>2</sup>}}).}}<ref name="SmithConference"/>

Peter Challenor, a scientist from the [[National Oceanography Centre]] in the United Kingdom, was quoted in [[Susan Casey|Casey]]'s book in 2010 as saying: "We don't have that random messy theory for nonlinear waves. At all." He added, "People have been working actively on this for the past 50 years at least. We don't even have the start of a theory."<ref name="TheWeek"/><ref name="Casey2010"/>

In 2006, Smith proposed that the IACS recommendation 34 pertaining to standard wave data be modified so that the minimum design wave height be increased to {{convert|65|ft|m|1|order=flip|abbr=on}}. He presented analysis that sufficient evidence exists to conclude that {{convert|66|ft|m|1|order=flip|abbr=on}} high waves can be experienced in the 25-year lifetime of oceangoing vessels, and that {{convert|98|ft|m|1|order=flip|abbr=on}} high waves are less likely, but not out of the question. Therefore, a design criterion based on {{convert|36|ft|m|1|order=flip|abbr=on}} high waves seems inadequate when the risk of losing crew and cargo is considered. Smith also proposed that the dynamic force of wave impacts should be included in the structural analysis.<ref name="SmithBook">{{cite book  | last      =  Smith
 | first      = Craig
 | date       = 2006
 | title      = Extreme Waves
 | url        = https://archive.org/details/extremewaves00smit
 | url-access =  registration
 | publisher  = Joseph Henry Press
 | isbn       = 978-0309100625
 | quote      = There is sufficient evidence to conclude that 66-foot-high waves can be experienced in the 25-year lifetime of oceangoing vessels and that 98-foot-high waves are less likely, but not out of the question. Therefore, a design criterion based on 36-foot-high waves seems inadequate when the risk of losing crew and cargo is considered. }}</ref>
The Norwegian offshore standards now consider extreme severe wave conditions and require that a 10,000-year wave does not endanger the ships' integrity.<ref name="rosenthal"/> W. Rosenthal noted that as of 2005, rogue waves were not explicitly accounted for in Classification Society's rules for ships' design.<ref name="rosenthal">{{cite web
 | url        = http://www.soest.hawaii.edu/PubServices/2005pdfs/Rosenthal.pdf
 | title      = Results of the MAXWAVE project
 | last       = Rosenthal
 | first      = W
 | date       = 2005
 | website    = www.soest.hawaii.edu
 | access-date= 14 January 2016
 | quote      = The Norwegian offshore standards consider extreme severe wave conditions by requiring that a 10,000-year wave does not endanger the structure’s integrity (Accidental Limit State, ALS).}}</ref> As an example, [[DNV GL]], one of the world's largest international certification bodies and classification society with main expertise in technical assessment, advisory, and risk management publishes their Structure Design Load Principles which remain largely based on the Significant Wave Height, and as of January 2016, still have not included any allowance for rogue waves.<ref name="DNVGL">{{cite web
 |url         = http://www.gl-group.com/infoServices/rules/pdfs/gl_i-2-2_e.pdf
 |archive-url = https://web.archive.org/web/20140912042308/http://www.gl-group.com/infoServices/rules/pdfs/gl_i-2-2_e.pdf
 |url-status    = dead
 |archive-date = 2014-09-12
 |title       = Rules for Classification and Construction
 |date        = 2011
 |website     = www.gl-group.com/
 |publisher   = Germanischer Lloyd SE
 |location    = Hamburg, Germany
 |access-date = 13 January 2016
 |quote       = General Terms and Conditions of the respective latest edition will be applicable. See Rules for Classification and Construction, I – Ship Technology, Part 0 – Classification and Surveys.
}}</ref>

The U.S. Navy historically took the design position that the largest wave likely to be encountered was {{convert|21.4|m|ft|abbr=on}}. Smith observed in 2007 that the navy now believes that larger waves can occur and the possibility of extreme waves that are steeper (i.e. do not have longer wavelengths) is now recognized. The navy has not had to make any fundamental changes in ship design due to new knowledge of waves greater than 21.4&nbsp;m because the ships are built to higher standards than required.<ref name="SmithConference"/>

The more than 50 classification societies worldwide each has different rules. However, most new ships are built to the standards of the 12 members of the [[International Association of Classification Societies]], which implemented two sets of common structural rules - one for oil tankers and one for bulk carriers, in 2006. These were later harmonised into a single set of rules.<ref name="IACS Common Structural Rules">{{cite web |title=International Association of Classification Societies |url=http://www.iacs.org.uk/publications/common-structural-rules/ |website=IACS |access-date=1 June 2020}}</ref>