Standard ports (Dover, Plymouth, Portsmouth etc) have full tidal predictions in the almanac. Secondary ports don't get their own curve - instead you apply time and height differences to a named standard port to work out times and heights of HW and LW locally.
Almanac difference tables give four columns: MHWS, MHWN, MLWN, MLWS (mean high/low water springs/neaps). You work out where today sits on the springs-neaps cycle at the standard port (using the standard port's actual predicted range) and interpolate the difference figure proportionally - not just averaged, unless the range happens to be exactly halfway.
Secondary ports don't have their own tidal curve diagram - you must use the standard port's curve, but plot your own calculated secondary port HW time and height onto it, then read intermediate heights/times exactly as you would for a standard port (using the range to pick springs, neaps or interpolated curve).
Your plotted course on the chart is the course over the ground you WANT to make good - but the boat won't travel exactly along that line. Wind, tide and leeway push it off track. The course to steer (CTS) is the compass heading you actually give the helmsman so that, after all that pushing, the boat ends up on the intended track.
1. Draw the intended track (the rhumb line you want to sail) from departure to destination.
2. From the start point, plot the tidal vector for the time interval you'll be at sea (direction the tide sets, length = rate x time in hours).
3. From the end of the tide vector, swing an arc with your boat speed through the water as radius until it cuts the intended track.
4. The line from the end of the tide vector to that cutting point is your water track - the direction you must steer through the water (before leeway) to end up on the ground track.
5. Apply leeway (add or subtract degrees depending on which way the wind pushes you) to get the course to steer through the water.
6. Convert True to Magnetic to Compass using variation then deviation (remember: True Virgins Make Dull Company, add west, subtract east - or the modern mnemonic error East compass least).
The International Regulations for Preventing Collisions at Sea 1972 (Colregs) apply to all vessels on the high seas and connected navigable waters. Yachtmaster Theory tests them hard, especially Part B (steering and sailing), Part C (lights) and Part D (sound and light signals) plus the Annexes.
All-round white, red, green and yellow lights, plus masthead (steaming) lights. Key ranges for vessels 50m+: masthead 6nm, sidelights 3nm, sternlight 3nm. Under 12m vessels may combine lights or use an all-round white plus sidelights. NUC shows two all-round red lights in a vertical line; RAM shows red-white-red. A vessel towing over 200m shows a diamond shape by day and extra lights by night. Sailing vessels under sail alone never show a masthead light.
A Yachtmaster must be able to read a shipping forecast, interpret a synoptic chart, and forecast locally from cloud, wind and pressure trends. Offshore, you cannot just check an app before leaving harbour and forget it - conditions change over days at sea.
Always delivered in the same order: gale warnings, general synopsis (with system positions and pressure, movement and forecast timing), then area forecasts (wind, weather, visibility) for the 31 sea areas. Learn the order the areas are read in (roughly clockwise from Viking) so you can find your area fast under pressure.
Know these three cold - they are the boundary cases examiners love.
These apply to gale warnings specifically. Mixing these up is one of the most common exam errors.
A warm front brings a slow pressure drop, thickening cloud (Ci to As to Ns), rain and then a lift in temperature as it passes. A cold front is faster and more violent - a sharp wind veer, heavy showers, cumulonimbus, then clearer, colder air behind. An occluded front is where a cold front catches a warm front.
Stand with your back to the true wind in the Northern Hemisphere and lower pressure is on your left. This lets you estimate a depression's position and track without instruments.
Candidates confuse true and apparent wind, forget that gale timing words refer to onset not duration, and misread synoptic chart isobar spacing (tight isobars = strong wind, not just 'bad weather'). Always cross-check the forecast against what you actually observe at sea.
Under SOLAS Chapter V (via the Merchant Shipping Regulations) the skipper of any vessel must plan a passage before setting off, however short. This is not optional paperwork - it is a legal requirement and a common exam trap is thinking it only applies to big ships.
Pilotage is used in confined waters, harbours, and rivers where fixing by cross-bearings or GPS every few minutes is essential. Key techniques:
A good plan records: departure and destination, waypoints with courses and distances, tidal predictions, expected weather, contingencies, and communication/safety arrangements. Examiners like to see this linked to actual pilotage decisions on the day, not just theory in isolation.
A boat's stability comes from the righting moment - the couple formed between the centre of gravity (G) and the centre of buoyancy (B) as the hull heels. Lower G (heavy keel, low ballast, engines and tanks kept low) means a stiffer, more stable boat. Free surface effect in slack tanks (fuel, water, bilge water) lets liquid slosh to the low side and raises the effective centre of gravity, reducing stability - always keep tanks pressed full or empty, and pump bilges dry.
The GZ curve plots righting lever against angle of heel. Key points to know: the angle of vanishing stability is where the righting lever drops to zero and the boat will capsize rather than right itself - typically well over 90 degrees for a good seagoing yacht, much lower for a poorly loaded or damaged one. The area under the curve represents the energy needed to capsize the vessel - a bigger area means a safer boat in extreme conditions.
Overloading, poor weight distribution, or free-flooding cockpits/lockers all degrade stability. Keep heavy gear low and central. Check the load line and the vessel's stability book or owner's manual if fitted.
Before bad weather hits: check the forecast (shipping forecast, Met Office inshore waters forecast, GRIB files), reduce sail early, secure all loose gear, brief the crew, clip on lifelines and don lifejackets, check hatches and washboards are secure, and identify a safe port or bolt-hole. Reef early - it is far easier and safer to reef before conditions deteriorate than to fight a sail down in a full gale.
Every crew member should wear a lifejacket (with crotch strap) and clip onto jackstays or strongpoints in heavy weather or at night. Carry an MOB recovery plan (Williamson turn or figure-of-eight) and practise it. Liferafts must be in-date for their service, stowed for quick launch, and crew must know the abandon-ship procedure - only step UP into a liferaft.