Reading notes

Offshore Theory · the whole course, in writing

Every chapter of the course, written out as a page you can read straight through. Each one links to the interactive version, where the same material comes with the chart, the drawings and the exercises.

What needs nothing first

Collision avoidance

The rules of the road, and navigating in reduced visibility.

• The nineteen COLREGs steering and sailing rulesWhere the nineteen rules sit and why that order matters, from application to restricted visibility: the COLREGs as Yachtmaster Offshore theory asks them.
• COLREGs Rule 14: head-on situationBoth alter to starboard and pass port to port. Test what you can see, two sidelights or mastheads in line, and why doubt settles it for you.
• COLREGs Rule 15: crossing situationThe vessel with the other on her starboard side keeps out of the way and avoids crossing ahead; the other holds on. For Yachtmaster Offshore theory.
• COLREGs Rule 16: action by the give-way vesselEarly and substantial action to keep well clear: give the alteration in time, and watch what happens to your options when you leave it too late.
• COLREGs Rule 17: action by the stand-on vesselKeep your course and speed, then the point where you may act and the close quarters step where you must, without turning to port for a vessel to port.
• COLREGs Rule 18: responsibilities between vesselsThe pecking order: power driven, sailing, fishing, restricted, not under command, and what a vessel constrained by her draught and a seaplane change.
• COLREGs Rule 19: conduct in restricted visibilityNot in sight of one another: safe speed, what radar alone gives you, and the alterations to avoid, as Yachtmaster Offshore theory questions put them.

The diesel engine

What every part does, and what goes wrong. Built on a three-dimensional engine you assemble, cut open and drive one circuit at a time.

• Marine diesel engine: structure and combustionHow a diesel lights itself: bearers and mounts, block and cylinders, the four strokes, and the fuel path from tank to injector, on a 3D engine.
• Diesel cooling, oil and raw water circuitsFollow the oil under pressure, the fresh water circuit and the raw water side: impeller, heat exchanger, belt, and the alarms you never argue with.
• Starting a diesel: batteries, starter and gearboxThe starting circuit and the drive: two battery banks, isolator rules, warning lights, gearbox, stern gland, shaft and anode, and what fouls a prop.
• Diesel engine jobs: impeller, filters and bleedingEleven jobs step by step: strainer and impeller, oil and fuel filters, bleeding the fuel system, belt tension, and hand starting with decompressors.
• Diesel faults: smoke colour, checks and sparesDaily checks before you turn the key, the first thirty seconds, what blue, black and white smoke each mean, and how a symptom leads to one part.

Buoyage

IALA A and B. Laterals, cardinals, isolated danger, safe water. Topmarks, colours, light characteristics — and which side you pass each one.

• Which side to pass a buoy, and why it dependsDecide which side of each mark to pass: what a cardinal actually tells you, which way the channel runs, where it splits, and why region B reverses the red.
• Reading buoy lights at night and on the chartRead a light by its rhythm, colour and period, learn the cardinal clock code, and find the same buoy written in chart abbreviations.

Lights and shapes of vessels

Rules 20 to 31. What every vessel shows by day and by night, how the two say the same thing, and what she sounds like when you cannot see her at all.

• Navigation lights and shapes: what a vessel showsMasthead lights, sidelights, sternlight and the arcs they cover, plus the day shapes: practice for the RYA Yachtmaster Offshore theory exam.
• Identifying vessels by their lights and shapesName the vessel from her lights: not under command, restricted in her ability to manoeuvre, fishing, towing, pilot. Built up one lamp at a time.
• Lights from your own bearing: what you can sayThe same vessel looks different from every angle. Walk around her, judge range and aspect, and decide what one bearing lets you conclude.
• Sound signals in fog and in sight of each otherShort and prolonged blasts build every signal: identify a vessel in fog by what you hear, and give the manoeuvring signals used in sight of her.

The chart series

Module 01 · The chart

What a chart is, and how to read the paper and the ground under it.

• Reading a nautical chart: position, distance, bearingRead a paper chart for the RYA Yachtmaster Offshore theory exam: latitude and longitude to tenths, distance off the side scale, bearings with a plotter.
• Chart depths: soundings, contours and drying heightsSoundings, depth contours and colour, drying heights underlined on green, and how wrecks, rocks and danger lines tell you what water you have.

Module 02 · Direction, distance and time

Three quantities you cannot navigate without, and the sums that join them.

• True, magnetic and compass: variation and deviationThree norths and one heading, as the RYA Yachtmaster Offshore theory exam asks: read the rose, update variation, apply deviation, convert both ways.
• Speed, distance and time calculations for passagesAny two of speed, distance and time give you the third. Turn minutes into decimals, measure legs off the chart, and keep water and ground speeds apart.
• UTC, BST and time zones in almanac tablesOne instant, several clocks: convert between UTC, local time and BST, read the almanac zone sign the right way round, and give an ETA in another clock.

Module 03 · Where you are

Everything that needs no tide: bearings, transits, the sounding as a line, and how much each one is worth.

• Position lines: bearings, transits and soundingsOne line at a time: plot a compass bearing back from the object, use a transit, a sounding and a distance off, and judge which line you can trust.
• Getting a fix: crossing bearings and the cocked hatCross two position lines for a fix, see why the angle of cut decides how big it is, and work a cocked hat: chartwork for Yachtmaster Offshore theory.
• Dead reckoning and running a position line onPlot course and distance run leg by leg, keep the reckoning through an alteration, and carry one position line forward to cross it with a later one.

Module 04 · Tides

How much water there is, when, and whether it is enough.

• Chart datum, tide levels and rangeChart datum and the words hung from it: charted depth, drying height, elevation, the four mean levels, HAT and LAT, and range from springs to neaps.
• Standard port tide tables and the tidal curveRead high and low water off the almanac page, then work the tidal curve both ways: the height at a given time, and the time for the height you need.
• Under-keel clearance and overhead clearanceSounding plus tide, minus draught and a safety margin. Correct the echo sounder, find the tide you need to cross, and what is left over the masthead.
• Tidal diamonds and the tidal stream atlasSet and rate from the tidal diamonds on the chart and from the atlas, worked between springs and neaps, and the tidal gates that decide when you go.

Module 05 · Where you're going

Everything that does need the stream: dead reckoning, estimated position, course to steer.

• Tidal streams and the estimated positionThe log cannot feel the stream. Draw one hour of it, apply it to your reckoning to get an estimated position, and measure what ignoring it costs.
• Leeway: how much, which side, and where it goesLeeway changes the course you steer and never the distance run. Judge how much, decide which side she goes, and lay the water track with both in order.
• Course to steer: the one hour vector triangleFrom the track you want, build the one hour triangle with stream and leeway and read off the course to steer. A Yachtmaster Offshore theory staple.

Module 06 · The almanac

From Skelmar to the Channel: the real book, its secondary ports and its coefficient.

• Using a nautical almanac: standard and secondary portsHow an almanac is made, then its tide sums: times and heights at a standard port, secondary port differences, and the Solent's special tidal curves.
• Tidal stream atlas, port entry, sun and moonRead a tidal stream atlas with the coefficient, carry the stream to the chart, check port entry, tidal gates, sun and moon, and plan a day from the book.