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</o:shapelayout></xml><![endif]--></head><body lang=EN-AU link="#0563C1" vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>This is an interesting question once you get into it. In Australia it is compounded by States having their own “States Waters” as well as the Commonwealth having its own waters. I once had to deal with a shipwreck whose stern was in the State of Victoria and whose bow was in the Commonwealth. There is an interesting discussion on the Geoscience Australia site <o:p></o:p></p><p class=MsoNormal><a href="https://www.ga.gov.au/scientific-topics/marine/jurisdiction">https://www.ga.gov.au/scientific-topics/marine/jurisdiction</a> that may be of interest as it talks also about general principals.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>In practice I use the 0 elevation contour or shapes of the coast provided by Government Agencies.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Cheers<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b><span style='font-size:12.0pt;font-family:Papyrus;mso-fareast-language:EN-AU'>Dr Iain Stuart<o:p></o:p></span></b></p><p class=MsoNormal><b><i><span style='font-size:12.0pt;font-family:Papyrus;mso-fareast-language:EN-AU'>JCIS Consultants <o:p></o:p></span></i></b></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'>P.O. Box 2397<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'>Burwood North<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'>NSW, 2134<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'>(02) 9701 0191<br>(0413) 380116 (m)<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>