{"id":375,"date":"2020-12-10T19:22:17","date_gmt":"2020-12-10T19:22:17","guid":{"rendered":"https:\/\/maritimesa.org\/nautical-science-grade-10\/?p=375"},"modified":"2020-12-10T19:22:17","modified_gmt":"2020-12-10T19:22:17","slug":"zone-designations-and-local-mean-time","status":"publish","type":"post","link":"https:\/\/maritimesa.org\/nautical-science-grade-10\/2020\/12\/10\/zone-designations-and-local-mean-time\/","title":{"rendered":"Zone designations and local mean time"},"content":{"rendered":"

Zone designations.<\/h4>\n

A ship\u2019s clocks will not necessarily be altered the moment she enters a new zone. The fact that she is crossing a dividing meridian and entering a new zone does not alter the time she is keeping. Her clocks are altered to suit the convenience of those onboard.<\/p>\n

Local mean time.<\/h4>\n

Local mean time (LMT) is a more precise indication of time and it reflects the actual time on a meridian. To derive LMT in a particular position, it is necessary to establish the GMT from the zone time one is operating in and thence to apply a correction derived from the actual longitude of the position (the longitude is converted to time). For example:<\/p>\n

A ship is steaming in zone (-2) and in position 18\u00b0 20\u2019 S 21\u00b0 35\u2019 E, the ship\u2019s clocks indicate the time as 1215 B. What is the GMT and LMT?<\/p>\n

\"\"<\/p>\n

Remember that GMT is 2 hours behind zone -2 and therefore when it is 1215 in zone -2, it is only 1015 at Greenwich. Remember that 15\u00b0 of longitude represents the angular distance the sun apparently moves in one hour.<\/p>\n","protected":false},"excerpt":{"rendered":"

Zone designations. A ship\u2019s clocks will not necessarily be altered the moment she enters a new zone. The fact that she is crossing a dividing meridian and entering a new zone does not alter the time she is keeping. Her clocks are altered to suit the convenience of those onboard. […]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,45,49],"tags":[],"class_list":["post-375","post","type-post","status-publish","format-standard","hentry","category-10-1-navigation","category-10-1-6-measurement-of-time-at-sea","category-10-1-6-4-zone-designations-and-local-mean-time"],"_links":{"self":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/posts\/375"}],"collection":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/comments?post=375"}],"version-history":[{"count":1,"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/posts\/375\/revisions"}],"predecessor-version":[{"id":377,"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/posts\/375\/revisions\/377"}],"wp:attachment":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/media?parent=375"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/categories?post=375"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-10\/wp-json\/wp\/v2\/tags?post=375"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}