{"id":47905,"date":"2026-01-15T22:23:08","date_gmt":"2026-01-15T22:23:08","guid":{"rendered":"https:\/\/maritimehub.co.uk\/?p=47905"},"modified":"2026-01-15T22:25:27","modified_gmt":"2026-01-15T22:25:27","slug":"colregs-shapes","status":"publish","type":"post","link":"https:\/\/maritimehub.co.uk\/colregs-shapes\/","title":{"rendered":"COLREGs \u2013 Shapes"},"content":{"rendered":"\n<p><em>What vessels are telling you in daylight \u2014 and why daylight collisions still happen<\/em><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Contents<\/h2>\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>Why Shapes Still Matter in Modern Navigation<\/li>\n\n\n\n<li>When Shapes Must Be Displayed<\/li>\n\n\n\n<li>The Core Shapes Every OOW Must Recognise Instantly<\/li>\n\n\n\n<li>Power-Driven Vessels and the Absence of Shapes<\/li>\n\n\n\n<li>Vessels Not Under Command<\/li>\n\n\n\n<li>Vessels Restricted in Their Ability to Manoeuvre<\/li>\n\n\n\n<li>Vessels Constrained by Their Draught<\/li>\n\n\n\n<li>Fishing Vessels<\/li>\n\n\n\n<li>Towing and Pushing Operations<\/li>\n\n\n\n<li>Sailing Vessels and Special Cases<\/li>\n\n\n\n<li>Anchored and Aground Vessels<\/li>\n\n\n\n<li>Dredging, Underwater, and Obstruction Operations<\/li>\n\n\n\n<li>Small Craft, Non-Compliance, and Missing Shapes<\/li>\n\n\n\n<li>Common Misidentifications and Daylight Traps<\/li>\n\n\n\n<li>Using Shapes with Radar, AIS, and Visual Bearings<\/li>\n\n\n\n<li>What to Do When Shapes Are Missing or Conflicting<\/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. Why Shapes Still Matter in Modern Navigation<\/h2>\n\n\n\n<p>A persistent myth on modern bridges is:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\u201cShapes are obsolete \u2014 we have AIS and radar.\u201d<\/p>\n<\/blockquote>\n\n\n\n<p>This belief has contributed directly to <strong>daylight collisions<\/strong>.<\/p>\n\n\n\n<p>Shapes exist because:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>daylight removes the contrast advantage of lights<\/li>\n\n\n\n<li>radar does not show <strong>operational constraints<\/strong><\/li>\n\n\n\n<li>AIS can be wrong, delayed, or misleading<\/li>\n<\/ul>\n\n\n\n<p>Shapes answer a question electronics often cannot:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p><em>\u201cHow free is this vessel to manoeuvre?\u201d<\/em><\/p>\n<\/blockquote>\n\n\n\n<p>Ignoring shapes means ignoring <strong>intent and limitation<\/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. When Shapes Must Be Displayed<\/h2>\n\n\n\n<p>Shapes must be displayed:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>from sunrise to sunset<\/li>\n\n\n\n<li>when required by the vessel\u2019s condition<\/li>\n\n\n\n<li>regardless of visibility quality<\/li>\n<\/ul>\n\n\n\n<p>They must be:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>clearly visible<\/li>\n\n\n\n<li>properly rigged<\/li>\n\n\n\n<li>correctly positioned<\/li>\n<\/ul>\n\n\n\n<p>If a vessel is required to display shapes and does not, that vessel is <strong>non-compliant<\/strong> \u2014 but your responsibility to avoid collision remains.<\/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 Core Shapes Every OOW Must Recognise Instantly<\/h2>\n\n\n\n<p>Every OOW must instantly recognise:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>ball<\/li>\n\n\n\n<li>diamond<\/li>\n\n\n\n<li>cone (apex up or down)<\/li>\n<\/ul>\n\n\n\n<p>Recognition must be <strong>immediate<\/strong>, not analytical.<\/p>\n\n\n\n<p>If you are stopping to \u201cwork it out,\u201d you are already late.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">4. Power-Driven Vessels and the Absence of Shapes<\/h2>\n\n\n\n<p>Most power-driven vessels underway display <strong>no shapes<\/strong>.<\/p>\n\n\n\n<p>This absence itself is information.<\/p>\n\n\n\n<p>It tells you:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the vessel considers itself fully manoeuvrable<\/li>\n\n\n\n<li>normal crossing, overtaking, and head-on rules apply<\/li>\n<\/ul>\n\n\n\n<p>Do not assume absence of shapes equals absence of risk.<\/p>\n\n\n\n<p>It simply means <strong>no declared restriction<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">5. Vessels Not Under Command<\/h2>\n\n\n\n<p>A vessel not under command displays <strong>two black balls in a vertical line<\/strong>.<\/p>\n\n\n\n<p>This is one of the most critical shapes.<\/p>\n\n\n\n<p>Operational meaning:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the vessel cannot manoeuvre<\/li>\n\n\n\n<li>it may drift unpredictably<\/li>\n\n\n\n<li>engine, steering, or propulsion failure is likely<\/li>\n<\/ul>\n\n\n\n<p>If you see NUC shapes, your priority is <strong>early, wide clearance<\/strong>.<\/p>\n\n\n\n<p>Do not attempt to negotiate close passing.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">6. Vessels Restricted in Their Ability to Manoeuvre<\/h2>\n\n\n\n<p>These vessels display <strong>ball\u2013diamond\u2013ball<\/strong> vertically.<\/p>\n\n\n\n<p>This shape combination means:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the vessel is constrained by its work<\/li>\n\n\n\n<li>it cannot comply with COLREGs normally<\/li>\n\n\n\n<li>you must keep clear<\/li>\n<\/ul>\n\n\n\n<p>Typical operations include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>dredging<\/li>\n\n\n\n<li>cable laying<\/li>\n\n\n\n<li>underwater operations<\/li>\n\n\n\n<li>buoy maintenance<\/li>\n<\/ul>\n\n\n\n<p>Ignoring RAM shapes is a classic daylight accident precursor.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">7. Vessels Constrained by Their Draught<\/h2>\n\n\n\n<p>A vessel constrained by draught may display <strong>a black cylinder<\/strong>.<\/p>\n\n\n\n<p>This is a <strong>statement of limitation<\/strong>, not priority.<\/p>\n\n\n\n<p>It means:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the vessel\u2019s available manoeuvring options are severely limited<\/li>\n\n\n\n<li>deviation from course may be unsafe<\/li>\n<\/ul>\n\n\n\n<p>In narrow channels, this shape demands <strong>early and decisive avoidance<\/strong>, not last-minute compliance debates.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">8. Fishing Vessels<\/h2>\n\n\n\n<p>Fishing vessels display:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>two cones apex together (hourglass shape)<\/li>\n<\/ul>\n\n\n\n<p>Operational reality:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>fishing gear may extend far from the vessel<\/li>\n\n\n\n<li>the vessel may turn unpredictably<\/li>\n\n\n\n<li>gear may not be visible<\/li>\n<\/ul>\n\n\n\n<p>Fishing shapes indicate <strong>hidden risk<\/strong>, not just vessel type.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">9. Towing and Pushing Operations<\/h2>\n\n\n\n<p>Towing vessels may display a <strong>diamond shape<\/strong> when the tow exceeds certain lengths.<\/p>\n\n\n\n<p>This warns that:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the tow may trail far astern<\/li>\n\n\n\n<li>the tug\u2019s manoeuvrability is limited<\/li>\n\n\n\n<li>passing close astern may foul the tow<\/li>\n<\/ul>\n\n\n\n<p>Shapes here warn you about <strong>what radar might not show<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">10. Sailing Vessels and Special Cases<\/h2>\n\n\n\n<p>Sailing vessels normally display <strong>no shapes<\/strong>.<\/p>\n\n\n\n<p>When using engines, they should display a <strong>cone apex down<\/strong>, indicating power-driven status.<\/p>\n\n\n\n<p>Operational trap:<\/p>\n\n\n\n<p>Many sailing vessels motor-sail without displaying the cone.<\/p>\n\n\n\n<p>Do not assume compliance.<\/p>\n\n\n\n<p>Treat sailing vessels with caution and margin.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">11. Anchored and Aground Vessels<\/h2>\n\n\n\n<p>Anchored vessels display <strong>one black ball<\/strong>.<\/p>\n\n\n\n<p>Aground vessels display <strong>three black balls<\/strong> in a vertical line.<\/p>\n\n\n\n<p>Daylight groundings are often underestimated because:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the vessel appears stationary<\/li>\n\n\n\n<li>radar vectors show no movement<\/li>\n\n\n\n<li>officers assume clearance exists<\/li>\n<\/ul>\n\n\n\n<p>Shapes tell you <strong>why the vessel is stationary<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">12. Dredging, Underwater, and Obstruction Operations<\/h2>\n\n\n\n<p>Some RAM vessels display additional shapes indicating:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>safe side to pass<\/li>\n\n\n\n<li>obstructed side<\/li>\n<\/ul>\n\n\n\n<p>These shapes are critical during daylight operations near ports, channels, and offshore works.<\/p>\n\n\n\n<p>Ignoring these indicators leads to <strong>contact accidents<\/strong>, not just collisions.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">13. Small Craft, Non-Compliance, and Missing Shapes<\/h2>\n\n\n\n<p>In reality:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>many small craft do not display shapes<\/li>\n\n\n\n<li>some vessels display incorrect shapes<\/li>\n\n\n\n<li>rigging may be poor or obscured<\/li>\n<\/ul>\n\n\n\n<p>This does not invalidate the system.<\/p>\n\n\n\n<p>It means <strong>professional ships must compensate<\/strong>.<\/p>\n\n\n\n<p>Expect non-compliance \u2014 never rely on perfection.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">14. Common Misidentifications and Daylight Traps<\/h2>\n\n\n\n<p>Recurring errors include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>assuming no shapes means no constraint<\/li>\n\n\n\n<li>mistaking RAM vessels for fishing vessels<\/li>\n\n\n\n<li>ignoring cylinders in narrow channels<\/li>\n\n\n\n<li>trusting AIS status over visual shapes<\/li>\n\n\n\n<li>failing to notice shapes against cluttered backgrounds<\/li>\n<\/ul>\n\n\n\n<p>Daylight reduces contrast \u2014 shape awareness must increase.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">15. Using Shapes with Radar, AIS, and Visual Bearings<\/h2>\n\n\n\n<p>Shapes provide <strong>context<\/strong>.<\/p>\n\n\n\n<p>Radar provides <strong>movement<\/strong>.<\/p>\n\n\n\n<p>AIS provides <strong>declared status<\/strong>.<\/p>\n\n\n\n<p>When these disagree:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>trust physical reality first<\/li>\n\n\n\n<li>increase CPA<\/li>\n\n\n\n<li>reduce speed if necessary<\/li>\n\n\n\n<li>call the Master early<\/li>\n<\/ul>\n\n\n\n<p>Visual evidence beats digital claims.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">16. What to Do When Shapes Are Missing or Conflicting<\/h2>\n\n\n\n<p>When shapes are unclear or contradictory:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>assume reduced manoeuvrability<\/li>\n\n\n\n<li>avoid close-quarters situations<\/li>\n\n\n\n<li>take early and obvious action<\/li>\n\n\n\n<li>communicate if appropriate<\/li>\n\n\n\n<li>document concerns in the log<\/li>\n<\/ul>\n\n\n\n<p>Uncertainty is not neutral \u2014 it is risk.<\/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>COLREGs shapes \u00b7 daytime navigation \u00b7 vessel identification \u00b7 restricted manoeuvrability \u00b7 bridge watchkeeping \u00b7 collision avoidance<br><\/p>\n","protected":false},"excerpt":{"rendered":"<p>What vessels are telling you in daylight \u2014 and why daylight collisions still happen Contents Use the links below to jump to any section: 1. Why Shapes Still Matter in Modern Navigation A persistent myth on modern bridges is: \u201cShapes are obsolete \u2014 we have AIS and radar.\u201d This belief has contributed directly to daylight [&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":[10,1,11,14,12],"tags":[8859],"class_list":["post-47905","post","type-post","status-publish","format-standard","hentry","category-bridge","category-latest","category-navigation","category-on-deck","category-watchkeeping","tag-8859"],"acf":[],"_links":{"self":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/47905","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=47905"}],"version-history":[{"count":1,"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/47905\/revisions"}],"predecessor-version":[{"id":47906,"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/47905\/revisions\/47906"}],"wp:attachment":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Fmedia&parent=47905"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Fcategories&post=47905"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Ftags&post=47905"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}