{"id":47926,"date":"2026-01-15T22:45:09","date_gmt":"2026-01-15T22:45:09","guid":{"rendered":"https:\/\/maritimehub.co.uk\/?p=47926"},"modified":"2026-01-15T22:45:25","modified_gmt":"2026-01-15T22:45:25","slug":"running-fixes","status":"publish","type":"post","link":"https:\/\/maritimehub.co.uk\/running-fixes\/","title":{"rendered":"Running Fixes"},"content":{"rendered":"\n<p>How navigators turn movement into position \u2014 and why this method punishes assumptions<br><br>Contents<\/p>\n\n\n\n<p>Use the links below to jump to any section:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>What a Running Fix Really Is<\/li>\n\n\n\n<li>Why Running Fixes Exist<\/li>\n\n\n\n<li>The Concept of Advancing a Line of Position<\/li>\n\n\n\n<li>When Running Fixes Are Appropriate<\/li>\n\n\n\n<li>Step-by-Step Logic (Without Maths)<\/li>\n\n\n\n<li>Accuracy and the Cost of Assumptions<\/li>\n\n\n\n<li>Common Errors in Running Fixes<\/li>\n\n\n\n<li>Running Fixes in Coastal and Confined Waters<\/li>\n\n\n\n<li>When Not to Use a Running Fix<\/li>\n\n\n\n<li>Professional Use of Running Fixes on the Bridge<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">1. What a Running Fix Really Is<\/h2>\n\n\n\n<p>A <strong>running fix<\/strong> is a position determined using <strong>one object observed at two different times<\/strong>, combined with the ship\u2019s movement between those observations.<\/p>\n\n\n\n<p>It exists because reality is imperfect.<\/p>\n\n\n\n<p>Sometimes there is:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>only one good landmark<\/li>\n\n\n\n<li>poor visibility in one direction<\/li>\n\n\n\n<li>limited charted features<\/li>\n<\/ul>\n\n\n\n<p>A running fix accepts this limitation and works with it.<\/p>\n\n\n\n<p>It is not a precise fix.<br>It is a <strong>disciplined estimate with structure<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">2. Why Running Fixes Exist<\/h2>\n\n\n\n<p>Running fixes exist to answer a simple operational question:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p><em>\u201cWhere am I now, given where I was earlier and how I moved?\u201d<\/em><\/p>\n<\/blockquote>\n\n\n\n<p>They allow navigation to continue when ideal fixing conditions do not exist.<\/p>\n\n\n\n<p>Historically, they were essential.<br>Today, they remain valuable because they <strong>force awareness of movement<\/strong>, something electronics often hide.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">3. The Concept of Advancing a Line of Position<\/h2>\n\n\n\n<p>When a bearing is taken, it creates a line of position.<\/p>\n\n\n\n<p>That line is true <strong>only at the moment it was observed<\/strong>.<\/p>\n\n\n\n<p>In a running fix, that line is then <strong>moved forward<\/strong> along the ship\u2019s estimated course and distance run to the time of the second observation.<\/p>\n\n\n\n<p>This creates an <em>advanced<\/em> line of position.<\/p>\n\n\n\n<p>Where the second bearing intersects the advanced line is the estimated position.<\/p>\n\n\n\n<p>This method assumes one thing only:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>The ship actually went where you think it did.<\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">4. When Running Fixes Are Appropriate<\/h2>\n\n\n\n<p>Running fixes are most useful when:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>only one suitable object is available<\/li>\n\n\n\n<li>visibility is limited in one sector<\/li>\n\n\n\n<li>landmarks appear sequentially<\/li>\n\n\n\n<li>coastal features are sparse<\/li>\n<\/ul>\n\n\n\n<p>They are common in open coastal waters and approaches where fixes are infrequent but progress must still be monitored.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">5. Step-by-Step Logic (Without Maths)<\/h2>\n\n\n\n<p>The logic of a running fix is simple:<\/p>\n\n\n\n<p>First, take a bearing to a known object and plot it.<br>Then, continue on a steady course and speed.<br>Later, take a second bearing to the same object.<br>Advance the first line by the distance run.<br>The intersection gives your estimated position.<\/p>\n\n\n\n<p>The method works because <strong>time creates separation<\/strong> between observations.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">6. Accuracy and the Cost of Assumptions<\/h2>\n\n\n\n<p>Running fixes are sensitive to error.<\/p>\n\n\n\n<p>If any of the following are wrong, the fix degrades:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>course made good<\/li>\n\n\n\n<li>speed through the water<\/li>\n\n\n\n<li>set and drift<\/li>\n\n\n\n<li>steering accuracy<\/li>\n<\/ul>\n\n\n\n<p>Unlike other fixes, errors here are invisible. The fix may look neat and still be wrong.<\/p>\n\n\n\n<p>This is why running fixes reward honesty and punish optimism.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">7. Common Errors in Running Fixes<\/h2>\n\n\n\n<p>The most common mistakes include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>assuming course made good equals course steered<\/li>\n\n\n\n<li>ignoring current<\/li>\n\n\n\n<li>advancing the line incorrectly<\/li>\n\n\n\n<li>taking bearings too close together in time<\/li>\n\n\n\n<li>trusting the result more than the inputs<\/li>\n<\/ul>\n\n\n\n<p>A running fix is only as good as the navigator\u2019s discipline.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">8. Running Fixes in Coastal and Confined Waters<\/h2>\n\n\n\n<p>In confined waters, running fixes become risky.<\/p>\n\n\n\n<p>High traffic density, frequent alterations, and variable currents make assumptions unstable.<\/p>\n\n\n\n<p>They should be used cautiously and always backed up by other information such as depth, transits, or ranges.<\/p>\n\n\n\n<p>A running fix should never be the sole source of confidence near danger.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">9. When Not to Use a Running Fix<\/h2>\n\n\n\n<p>Running fixes should be avoided when:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the ship is altering course frequently<\/li>\n\n\n\n<li>speed is changing<\/li>\n\n\n\n<li>current is strong or uncertain<\/li>\n\n\n\n<li>visual identification is doubtful<\/li>\n\n\n\n<li>precision is required immediately<\/li>\n<\/ul>\n\n\n\n<p>In these situations, waiting for a better fix is safer than forcing an estimate.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">10. Professional Use of Running Fixes on the Bridge<\/h2>\n\n\n\n<p>Professional navigators treat running fixes as <strong>trend indicators<\/strong>, not absolute truth.<\/p>\n\n\n\n<p>They are used to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>confirm general progress<\/li>\n\n\n\n<li>detect unexpected drift<\/li>\n\n\n\n<li>support planning decisions<\/li>\n\n\n\n<li>bridge gaps between stronger fixes<\/li>\n<\/ul>\n\n\n\n<p>They are rarely used alone and never without caution.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Closing Perspective<\/h2>\n\n\n\n<p>Running fixes teach a crucial lesson:<\/p>\n\n\n\n<p>Navigation is not about perfect information.<br>It is about <strong>understanding uncertainty and managing it honestly<\/strong>.<\/p>\n\n\n\n<p>A navigator who understands running fixes understands the cost of assumption \u2014 and that understanding carries into every other method.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Tags<\/h2>\n\n\n\n<p>running fixes \u00b7 advancing line of position \u00b7 coastal navigation \u00b7 visual navigation \u00b7 bridge watchkeeping \u00b7 chartwork<br><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>How navigators turn movement into position \u2014 and why this method punishes assumptions Contents Use the links below to jump to any section: 1. What a Running Fix Really Is A running fix is a position determined using one object observed at two different times, combined with the ship\u2019s movement between those observations. It exists [&hellip;]<\/p>\n","protected":false},"author":199,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"fifu_image_url":"","fifu_image_alt":"","c2c-post-author-ip":"","footnotes":""},"categories":[10,1,14],"tags":[8859],"class_list":["post-47926","post","type-post","status-publish","format-standard","hentry","category-bridge","category-latest","category-on-deck","tag-8859"],"acf":[],"_links":{"self":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/47926","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/users\/199"}],"replies":[{"embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Fcomments&post=47926"}],"version-history":[{"count":1,"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/47926\/revisions"}],"predecessor-version":[{"id":47927,"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/47926\/revisions\/47927"}],"wp:attachment":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Fmedia&parent=47926"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Fcategories&post=47926"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Ftags&post=47926"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}