{"id":46889,"date":"2026-01-02T14:15:47","date_gmt":"2026-01-02T14:15:47","guid":{"rendered":"https:\/\/maritimehub.co.uk\/?page_id=46889"},"modified":"2026-01-03T20:53:40","modified_gmt":"2026-01-03T20:53:40","slug":"cylinder-system-oil","status":"publish","type":"post","link":"https:\/\/maritimehub.co.uk\/cylinder-system-oil\/","title":{"rendered":"Cylinder &amp; System Oil"},"content":{"rendered":"\n<p><\/p>\n\n\n\n<p><strong>The Two Oils That Decide Engine Life<\/strong><\/p>\n\n\n\n<p>On large marine engines, lubricating oil is not \u201cjust oil\u201d. It is:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A wear-control system (film strength, anti-scuff, anti-wear)<\/li>\n\n\n\n<li>A chemistry system (acid neutralisation, detergency, dispersion)<\/li>\n\n\n\n<li>A cooling system (heat removal from bearings, pistons, crosshead)<\/li>\n\n\n\n<li>A sealing system (ring pack sealing and blow-by control)<\/li>\n\n\n\n<li>A condition-monitoring system (trend data that predicts failures early)<\/li>\n<\/ul>\n\n\n\n<p>On large crosshead two-strokes, lubrication is split into two worlds:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Cylinder oil (once-through): injected into the liner, then drained away<\/li>\n\n\n\n<li>System oil (circulating\/crankcase): filtered\/cooled and reused to lubricate bearings, crosshead, guides, piston cooling, etc.<\/li>\n<\/ul>\n\n\n\n<p>This article covers the full topic: selection (BN\/TBN), sulphur and cold corrosion, oil-in-water and water-in-oil, real-world oil \u201cfamilies\u201d, onboard management, common failure modes, and what chiefs actually do to keep wear under control.<\/p>\n\n\n\n<p><strong>Table of Contents<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Cylinder vs System Oil (The Clean Separation)<\/li>\n\n\n\n<li>What Each Oil Must Achieve (Functions &amp; Failure Modes)<\/li>\n\n\n\n<li>BN\/TBN Explained Properly (And Why It Matters)<\/li>\n\n\n\n<li>Selecting Cylinder Oil BN for Fuel Sulphur (Practical Guidance)<\/li>\n\n\n\n<li>Cylinder Oil Feed Rate (g\/kWh), ACC\/ALC Concepts, and What \u201cOver-Lube\u201d Looks Like<\/li>\n\n\n\n<li>System Oil Fundamentals (Grades, circuits, purification, piston cooling)<\/li>\n\n\n\n<li>Oil Contamination: Water, Fuel, Soot, Cat Fines, and Metals<\/li>\n\n\n\n<li>Oil-in-Water &amp; Water-in-Oil (Where it comes from, what it does, what to do)<\/li>\n\n\n\n<li>Real-World Oils &amp; Common Product Families (Examples + how to interpret them)<\/li>\n\n\n\n<li>Troubleshooting by Symptoms (Scavenge, drains, EGT, wear metals, purifier behaviour)<\/li>\n\n\n\n<li>Chief Engineer Level Operating Rules (Best practice that prevents claims)<\/li>\n\n\n\n<li>Case Scenarios: Slow Steaming, Low Sulphur, Scrubber Operation, Dual-Fuel<\/li>\n<\/ol>\n\n\n\n<p><strong>1. Cylinder vs System Oil <\/strong><\/p>\n\n\n\n<p><strong>Cylinder Oil (2-stroke crosshead engines)<\/strong><\/p>\n\n\n\n<p>Where it goes: directly into the liner via quills\/lubricator ports, timed around piston position.<\/p>\n\n\n\n<p>Where it ends up: scraped down \u2192 scavenge\/drain tank \u2192 waste \/ treatment.<\/p>\n\n\n\n<p>Why once-through? Because the cylinder is a chemically hostile environment:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>acids (from sulphur)<\/li>\n\n\n\n<li>high temperature<\/li>\n\n\n\n<li>combustion deposits and soot<\/li>\n<\/ul>\n\n\n\n<p><strong>System Oil (Circulating \/ crankcase oil)<\/strong><\/p>\n\n\n\n<p>Where it goes: sump \u2192 pumps \u2192 coolers\/filters \u2192 bearings, crosshead, guides, piston cooling, etc.<\/p>\n\n\n\n<p>Where it ends up: returns to sump, reused continuously.<\/p>\n\n\n\n<p>Why separate? The stuffing box\/diaphragm arrangement is designed to keep combustion products out of the crankcase and keep circulating oil out of the liner zone (in an ideal world).<\/p>\n\n\n\n<p><strong>2. What Each Oil Must Achieve<\/strong><\/p>\n\n\n\n<p><strong>Cylinder Oil must:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>form an oil film at liner\/ring interface<\/li>\n\n\n\n<li>control friction and prevent scuffing<\/li>\n\n\n\n<li>neutralise sulphuric acids (BN reserve)<\/li>\n\n\n\n<li>keep ring pack clean (detergency\/dispersancy)<\/li>\n\n\n\n<li>seal blow-by (ring pack stability)<\/li>\n<\/ul>\n\n\n\n<p>Typical visible outcomes when wrong:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>cold corrosion \/ corrosive liner wear<\/li>\n\n\n\n<li>ring sticking \/ broken rings<\/li>\n\n\n\n<li>excessive scavenge drain oil and sludge<\/li>\n\n\n\n<li>abnormal iron wear trends<\/li>\n<\/ul>\n\n\n\n<p><strong>System Oil must:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>provide hydrodynamic bearing films (main, crankpin, crosshead)<\/li>\n\n\n\n<li>cool and flush contaminants away<\/li>\n\n\n\n<li>protect against corrosion<\/li>\n\n\n\n<li>resist oxidation and foaming<\/li>\n\n\n\n<li>handle water ingress events without collapsing<\/li>\n<\/ul>\n\n\n\n<p>Typical outcomes when wrong:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>bearing wipe \/ overlay fatigue<\/li>\n\n\n\n<li>filter blockages<\/li>\n\n\n\n<li>purifier overload<\/li>\n\n\n\n<li>emulsions and sludge<\/li>\n\n\n\n<li>piston underside deposits (if piston cooling oil involved)<\/li>\n<\/ul>\n\n\n\n<p><strong>3. BN\/TBN Explained Properly<\/strong><\/p>\n\n\n\n<p>BN (Base Number) or TBN (Total Base Number) is a measure of an oil\u2019s alkalinity reserve\u2014its ability to neutralise acids.<\/p>\n\n\n\n<p>Why it matters:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Burning sulphur creates acid potential.<\/li>\n\n\n\n<li>If neutralisation is insufficient \u2192 corrosive wear.<\/li>\n\n\n\n<li>If alkalinity is excessive for the fuel\/conditions \u2192 deposit formation \/ polish \/ ring sticking risk (over-alkalinity can be just as destructive operationally).<\/li>\n<\/ul>\n\n\n\n<p>MAN guidance strongly links matching alkalinity to fuel sulphur, and also sets a minimum feed rate needed just for hydrodynamic lubrication.&nbsp;<\/p>\n\n\n\n<p><strong>4. Selecting Cylinder Oil BN for Fuel Sulphur<\/strong><\/p>\n\n\n\n<p><strong>The simple rule (and why it\u2019s only a starting point)<\/strong><\/p>\n\n\n\n<p>Higher sulphur fuel generally needs higher BN cylinder oil. Lower sulphur fuels generally need lower BN.<\/p>\n\n\n\n<p>MAN explicitly recommends matching alkaline content to sulphur content to avoid surplus alkalinity, and to use lower-BN oils when operating on low sulphur for extended periods.&nbsp;<\/p>\n\n\n\n<p><strong>Practical BN \u201cbands\u201d you\u2019ll see on ships<\/strong><\/p>\n\n\n\n<p>Typical categories commonly referenced in maker and supplier documentation include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>~15\u201340 BN (very low sulphur \/ distillates \/ LNG contexts on some engines)<\/li>\n\n\n\n<li>~70\u201385 BN<\/li>\n\n\n\n<li>~100 BN<\/li>\n\n\n\n<li>~140 BN (very high stress\/high sulphur\/specific conditions)<\/li>\n<\/ul>\n\n\n\n<p>MAN\u2019s own cylinder\/system oils letter lists these BN groupings and example product families across suppliers.&nbsp;<\/p>\n\n\n\n<p>Shell\u2019s portfolio also includes dedicated low-sulphur cylinder oils (e.g., for 0.1% and 0.5% fuels).&nbsp;<\/p>\n\n\n\n<p>Important: BN selection is not just fuel sulphur. It also depends on:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>liner temperature profile (cold corrosion risk)<\/li>\n\n\n\n<li>ring pack design and coatings<\/li>\n\n\n\n<li>engine tuning \/ EPL \/ slow steaming<\/li>\n\n\n\n<li>scrubber operation (if burning higher sulphur)<\/li>\n\n\n\n<li>actual wear inspection results<\/li>\n<\/ul>\n\n\n\n<p><strong>5. Cylinder Oil Feed Rate (g\/kWh) &amp; ACC Concepts<\/strong><\/p>\n\n\n\n<p><strong>The second lever (often more important than BN)<\/strong><\/p>\n\n\n\n<p>You manage cylinder lubrication with:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>BN selection<\/li>\n\n\n\n<li>feed rate (how much oil you actually deliver)<\/li>\n<\/ol>\n\n\n\n<p>MAN guidance includes a minimum feed rate recommendation of 0.60 g\/kWh for hydrodynamic purposes, and warns about surplus alkalinity if feed\/Bn is mismatched.&nbsp;<\/p>\n\n\n\n<p><strong>What \u201cunder-lube\u201d looks like<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>rising iron (Fe) wear trend<\/li>\n\n\n\n<li>scavenge area looks dry\/shiny<\/li>\n\n\n\n<li>polishing at reversal points<\/li>\n\n\n\n<li>increased blow-by symptoms<\/li>\n<\/ul>\n\n\n\n<p><strong>What \u201cover-lube\u201d looks like<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>wet scavenge + heavy deposits<\/li>\n\n\n\n<li>ring sticking tendency<\/li>\n\n\n\n<li>high scrape-down quantities<\/li>\n\n\n\n<li>deposits harden and then cause wear<\/li>\n<\/ul>\n\n\n\n<p><strong>ACC \/ Adaptive lubrication concepts (why it exists)<\/strong><\/p>\n\n\n\n<p>Modern approaches aim to vary feed with:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>engine load (fuel burnt)<\/li>\n\n\n\n<li>sulphur input<\/li>\n\n\n\n<li>engine condition<\/li>\n<\/ul>\n\n\n\n<p>This \u201cdose to conditions\u201d concept is embedded in manufacturer guidance and industry practice.&nbsp;<\/p>\n\n\n\n<p><strong>6. System Oil Fundamentals (Circulating Oil)<\/strong><\/p>\n\n\n\n<p><strong>What system oil lubricates on a crosshead two-stroke<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>main bearings<\/li>\n\n\n\n<li>crankpin bearings<\/li>\n\n\n\n<li>crosshead bearing and guides<\/li>\n\n\n\n<li>cam gear\/chain drives (maker dependent)<\/li>\n\n\n\n<li>piston cooling (often via telescopic pipe\/articulated arrangement)<\/li>\n<\/ul>\n\n\n\n<p><strong>The system oil circuit (what actually keeps it alive)<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>sump tank<\/li>\n\n\n\n<li>main lube oil pumps (duty\/standby)<\/li>\n\n\n\n<li>coolers (temp control)<\/li>\n\n\n\n<li>full-flow filters + bypass arrangements<\/li>\n\n\n\n<li>lube oil purifier (side stream cleaning)<\/li>\n\n\n\n<li>distribution manifold<\/li>\n<\/ul>\n\n\n\n<p>System oil is protected by continuous conditioning and can last a long time\u2014unless contamination enters.<\/p>\n\n\n\n<p><strong>7. Contamination: The Big Five That Kill Oils<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Water (fresh, sea, cooling leaks, condensation)<\/li>\n\n\n\n<li>Fuel (leaking pump seals, injector cooling arrangements, changeover mistakes)<\/li>\n\n\n\n<li>Soot\/insolubles (blow-by, combustion carryover)<\/li>\n\n\n\n<li>Cat fines \/ solids (less common in system oil on crosshead engines, more in trunk piston systems, but still possible via failures\/maintenance contamination)<\/li>\n\n\n\n<li>Wear metals (Fe, Cu, Pb, Sn, Al, Cr) indicating component distress<\/li>\n<\/ol>\n\n\n\n<p><strong>8. Oil-in-Water &amp; Water-in-Oil<\/strong><\/p>\n\n\n\n<p><strong>Water-in-Oil (the common engine-room crisis)<\/strong><\/p>\n\n\n\n<p>Sources<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>leaking cooler tubes (central cooling \u2194 LO)<\/li>\n\n\n\n<li>tank heating coil leak<\/li>\n\n\n\n<li>condensation<\/li>\n\n\n\n<li>improper draining practices<\/li>\n\n\n\n<li>purifier malfunction<\/li>\n<\/ul>\n\n\n\n<p>What water does<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>destroys film strength \u2192 bearing damage risk<\/li>\n\n\n\n<li>accelerates oxidation<\/li>\n\n\n\n<li>creates sludge\/emulsion<\/li>\n\n\n\n<li>triggers filter block and purifier overload<\/li>\n<\/ul>\n\n\n\n<p>Immediate actions <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>confirm by test (crackle, onboard kits, lab if possible)<\/li>\n\n\n\n<li>isolate suspect cooler (pressure test \/ bypass if permitted)<\/li>\n\n\n\n<li>increase purification\/dewatering focus<\/li>\n\n\n\n<li>reduce load if bearing safety is in question<\/li>\n\n\n\n<li>document everything (this becomes a claim story)<\/li>\n<\/ul>\n\n\n\n<p><strong>Oil-in-Water (less common but high consequence)<\/strong><\/p>\n\n\n\n<p>Often seen as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>sheen in bilges\/OWS issues<\/li>\n\n\n\n<li>pollution risk events<\/li>\n\n\n\n<li>leaks during transfers\/maintenance<\/li>\n<\/ul>\n\n\n\n<p>This is where compliance and engineering discipline overlap.<\/p>\n\n\n\n<p><strong>9. Real-World Oils &amp; Product Families (How to Interpret \u201cModels\u201d)<\/strong><\/p>\n\n\n\n<p>You asked for real-world examples. These aren\u2019t \u201crecommendations\u201d (makers\/charterer specs come first), but common reference points:<\/p>\n\n\n\n<p><strong>Cylinder oils (examples)<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Mobilgard\u2122 570 \u2013 positioned for two-stroke engines operating on HFO up to high sulphur levels; supplier product documentation exists under ExxonMobil\u2019s marine range. \u00a0<\/li>\n\n\n\n<li>Shell Alexia portfolio includes multiple BN grades and a specific push for low sulphur post-2020 operation (e.g., Alexia 40 concept). \u00a0<\/li>\n\n\n\n<li>Shell Alexia 140 \u2013 an ultra-high BN cylinder lubricant option discussed in Shell literature. \u00a0<\/li>\n\n\n\n<li>TotalEnergies Talusia Universal \u2013 marketed as a single-oil solution for a sulphur range 0.0\u20131.5% and dual-fuel\/LNG contexts; specific BN values appear on product pages (e.g., BN 57 on Talusia Universal 100 listing). \u00a0<\/li>\n<\/ul>\n\n\n\n<p><strong>System oils <\/strong><\/p>\n\n\n\n<p>System oils are typically \u201ccirculating\u201d oils designed for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>oxidation stability<\/li>\n\n\n\n<li>demulsibility<\/li>\n\n\n\n<li>anti-foam<\/li>\n\n\n\n<li>bearing protection<\/li>\n\n\n\n<li>compatibility with purifier operation<\/li>\n<\/ul>\n\n\n\n<p>Exact product choice depends on maker approvals and vessel practice.<\/p>\n\n\n\n<p><strong>10. Troubleshooting by Symptoms <\/strong><\/p>\n\n\n\n<p><strong>A) High iron (Fe) wear trend + visible liner etching<\/strong><\/p>\n\n\n\n<p>Most likely:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>cold corrosion (BN\/feed mismatch + operating profile)<\/li>\n\n\n\n<li>low load \/ slow steaming conditions<\/li>\n\n\n\n<li>liner temp too low for fuel\/sulphur conditions<\/li>\n<\/ul>\n\n\n\n<p>Actions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>verify BN selection vs fuel sulphur<\/li>\n\n\n\n<li>adjust feed rate cautiously<\/li>\n\n\n\n<li>review jacket water\/liner temperature strategy<\/li>\n\n\n\n<li>confirm by scavenge inspection and drain oil analysis<\/li>\n<\/ul>\n\n\n\n<p><strong>B) Wet scavenge + heavy deposits + ring sticking tendency<\/strong><\/p>\n\n\n\n<p>Most likely:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>over-lube for current sulphur\/conditions<\/li>\n\n\n\n<li>excess BN + low sulphur running<\/li>\n\n\n\n<li>poor injection\/combustion causing soot and sludge<\/li>\n<\/ul>\n\n\n\n<p>Actions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>reduce feed rate within maker guidance<\/li>\n\n\n\n<li>review fuel injection health (nozzle condition, timing, viscosity)<\/li>\n\n\n\n<li>inspect piston underside\/scavenge drains for deposit character<\/li>\n<\/ul>\n\n\n\n<p><strong>C) System oil purifier struggling + emulsions<\/strong><\/p>\n\n\n\n<p>Most likely:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>water ingress (cooler leak)<\/li>\n\n\n\n<li>incompatible top-ups<\/li>\n\n\n\n<li>degraded oil (oxidation\/varnish)<\/li>\n<\/ul>\n\n\n\n<p>Actions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>isolate and pressure test coolers<\/li>\n\n\n\n<li>dewater aggressively<\/li>\n\n\n\n<li>check filters \u0394P, review purifier temps\/settings<\/li>\n<\/ul>\n\n\n\n<p><strong>D) Bearings showing distress (metals Cu\/Pb\/Sn rising)<\/strong><\/p>\n\n\n\n<p>Most likely:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>water contamination<\/li>\n\n\n\n<li>film breakdown (viscosity drop, overheating)<\/li>\n\n\n\n<li>misalignment or overload<\/li>\n<\/ul>\n\n\n\n<p>Actions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>treat as urgent; reduce load and stabilise LO condition<\/li>\n\n\n\n<li>verify viscosity, water content, and temps immediately<\/li>\n<\/ul>\n\n\n\n<p><strong>11. Chief Engineer Operating Rules (The \u201cNo Excuses\u201d List)<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Never treat BN as a label\u2014treat it as chemistry.<\/li>\n\n\n\n<li>Feed rate is a controlled variable. Trend it like fuel consumption.<\/li>\n\n\n\n<li>Scrape-down oil and scavenge inspection are your early warning radar.<\/li>\n\n\n\n<li>Water is the fastest way to turn a normal day into an off-hire month.<\/li>\n\n\n\n<li>Log everything (fuel sulphur used, BN oil used, feed rate, inspections). When claims arise, evidence matters more than opinions.<\/li>\n<\/ol>\n\n\n\n<p><strong>12. Modern Scenarios You Must Account For<\/strong><\/p>\n\n\n\n<p><strong>Low-sulphur fuels &amp; IMO 2020 world<\/strong><\/p>\n\n\n\n<p>Dedicated low-sulphur cylinder oils exist, and makers have published guidance around BN selection and feed strategy for low sulphur operation.&nbsp;<\/p>\n\n\n\n<p><strong>Slow steaming \/ EPL \/ low-load running<\/strong><\/p>\n\n\n\n<p>Low load often increases cold corrosion risk. Lubrication must be tuned to operating profile, not just fuel spec.<\/p>\n\n\n\n<p><strong>Scrubber operation<\/strong><\/p>\n\n\n\n<p>If burning higher sulphur fuels with scrubbers, the cylinder lubrication strategy shifts again\u2014BN needs and feed strategy follow the sulphur actually burned in-cylinder (not just the emissions outcome).<\/p>\n\n\n\n<p><strong>Dual-fuel\/LNG operation<\/strong><\/p>\n\n\n\n<p>Different acid formation patterns and deposit behaviours; \u201cuniversal\u201d oils are marketed to simplify multi-fuel operation but still need condition monitoring and maker alignment.&nbsp;<\/p>\n\n\n\n<p><strong>Pinned Summary<\/strong><\/p>\n\n\n\n<p>Cylinder oil is a sacrificial chemical shield for the liner.<\/p>\n\n\n\n<p>System oil is a circulating life-support system for bearings and engine structure.<\/p>\n\n\n\n<p>Choose the right BN, control the feed rate, control water, and trend everything\u2014this is how engines survive modern fuels.<\/p>\n\n\n\n<p>If you want the next page Oil Monitoring &amp; Analysis, I can make it brutally practical:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>exact test panels (shipboard vs lab)<\/li>\n\n\n\n<li>alarm thresholds (what matters, what doesn\u2019t)<\/li>\n\n\n\n<li>wear-metal interpretation by component<\/li>\n\n\n\n<li>BN depletion logic and scrape-down correlation<\/li>\n\n\n\n<li>\u201cclaim-proof\u201d sampling and recordkeeping structure<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>The Two Oils That Decide Engine Life On large marine engines, lubricating oil is not \u201cjust oil\u201d. It is: On large crosshead two-strokes, lubrication is split into two worlds: This article covers the full topic: selection (BN\/TBN), sulphur and cold corrosion, oil-in-water and water-in-oil, real-world oil \u201cfamilies\u201d, onboard management, common failure modes, and what chiefs [&hellip;]<\/p>\n","protected":false},"author":199,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"fifu_image_url":"","fifu_image_alt":"","c2c-post-author-ip":"","footnotes":""},"categories":[43,10,7,8],"tags":[],"class_list":["post-46889","post","type-post","status-publish","format-standard","hentry","category-aux-machinery","category-bridge","category-engine-room","category-mechanical"],"acf":[],"_links":{"self":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/46889","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=46889"}],"version-history":[{"count":1,"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/46889\/revisions"}],"predecessor-version":[{"id":46890,"href":"https:\/\/maritimehub.co.uk\/?rest_route=\/wp\/v2\/posts\/46889\/revisions\/46890"}],"wp:attachment":[{"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Fmedia&parent=46889"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Fcategories&post=46889"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maritimehub.co.uk\/?rest_route=%2Fwp%2Fv2%2Ftags&post=46889"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}