SAMSA Skipper Category B (Coastal, up to 40 nm) Exam (South Africa) cheat sheet

Latitude is measured 0° to 90° north or south of the equator; longitude 0° to 180° east or west of the Greenwich meridian.

One minute of latitude equals one nautical mile (1852 m); use it to measure distance on the chart's latitude scale, never the longitude scale.

Speed, distance, time: Distance (nm) = Speed (kn) x Time (h); Time = Distance / Speed; Speed = Distance / Time.

A position fix requires at least two intersecting position lines; three or more lines give a cocked hat whose size indicates fix accuracy.

A running fix is obtained by advancing an earlier position line by the vessel's course and distance run over the elapsed time.

A transit (two charted objects in line) gives a position line with no compass error; a bearing and distance from one object gives a fix.

Compass error = Magnetic variation + Deviation; True bearing = Compass bearing + Easterly error (or minus Westerly error).

Dead reckoning position is derived from course steered and speed through the water; it ignores leeway and current, so it is an estimate only.

GPS position is referenced to WGS84 datum; if the chart uses a different datum, a datum shift must be applied to plotted positions.

Large scale charts show more detail over a smaller area and are preferred for pilotage and harbour approaches; small scale charts cover large areas for passage planning.

Chart datum is the level to which charted depths and drying heights are referenced; soundings are depths below chart datum.

Depths printed on the chart are in metres (or fathoms and feet as stated in the chart title); always check the chart's unit note before reading soundings.

Notices to Mariners amend charts and publications; a chart is not current until the latest notices affecting it have been applied.

Sailing Directions (Pilots) describe coastlines, hazards, port entry and local regulations; they supplement, not replace, the chart.

List of Lights gives light characteristics, ranges and heights; List of Radio Signals gives communications and port radio details.

A passage plan covers appraisal, planning, execution and monitoring, including no-go areas, abort points and contingency anchorages.

Under-keel clearance is charted depth plus height of tide minus vessel draught; allowance must be made for squat, swell and chart inaccuracies.

Spring tides occur near new and full moon when solar and lunar tidal forces align, giving the greatest tidal range; neap tides occur at quarter moons.

Rule of twelfths: in a 6-hour tide the rise or fall is 1/12, 2/12, 3/12, 3/12, 2/12, 1/12 of the range in each successive hour.

Height of tide at a given time = height of low water + fraction of range (using tide tables and the rule of twelfths or a tide curve).

Tidal streams flood toward the high-water direction and ebb toward the low-water direction; they are not the same as currents.

A sea breeze blows from sea to land by day; a land breeze blows from land to sea at night, driven by differential heating.

In the Southern Hemisphere, wind circulates clockwise around a low-pressure system and anticlockwise around a high-pressure system.

Buys Ballot's law (Southern Hemisphere): with your back to the wind, low pressure lies to your left.

Beaufort scale force 6 is a strong breeze (22-27 kn) with large waves and whitecaps; force 8 is a gale (34-40 kn).

Fog forms when air is cooled to its dew point; sea fog is common when warm moist air moves over a colder sea surface.

Rule 5 (lookout), Rule 6 (safe speed) and Rule 7 (risk of collision) apply at all times; risk is deemed to exist if the bearing of an approaching vessel does not appreciably change.

Rule 13: any vessel overtaking another must keep out of the way until finally past and clear, regardless of vessel type.

Rule 14 (head-on): both power-driven vessels alter course to starboard and pass port-to-port.

Rule 15 (crossing): the vessel with the other on her starboard side is the give-way vessel and must keep out of the way.

Rule 16/17: the give-way vessel takes early and substantial action; the stand-on vessel maintains course and speed but may act if collision cannot be avoided by the give-way vessel alone.

Rule 18 hierarchy: power-driven vessel gives way to sailing vessel, fishing vessel, vessel not under command and vessel restricted in ability to manoeuvre; the least manoeuvrable has priority.

IALA Region A (used in South Africa): port-hand lateral marks are red and can-shaped; starboard-hand marks are green and conical.

Safe water marks are red and white vertically striped with a red spherical topmark; isolated danger marks are red and black with two black spheres.

Cardinal marks indicate the safe side to pass: north (two cones up), east (base-to-base), south (two cones down), west (point-to-point); the topmarks are the primary cue.

A vessel turns about its pivot point, roughly one-third to one-quarter of the length from the bow when moving ahead; the stern swings wider than the bow.

Propeller transverse thrust: a right-handed propeller in ahead gear tends to walk the stern to starboard; in astern gear it walks the stern to port.

Stopping distance is much greater than turning circle diameter; a vessel cannot stop in less than several boat lengths even at moderate speed.

Anchoring: scope of about 5-7 times depth in chain (or 5-10 times in rope) in good holding; veer more in strong wind or poor holding.

When anchoring, the vessel should be brought up head to wind or current, with the anchor cable tending ahead and the anchor set by gentle astern power.

Mooring: head and stern lines control fore-and-aft movement, spring lines prevent surging, and breast lines hold the vessel alongside.

A vessel constrained by her draught, a vessel not under command and a vessel restricted in ability to manoeuvre display the appropriate shapes by day and lights by night.

Heaving-to is achieved by backing the headsail and lashing the helm to leeward, slowing the vessel and giving a steadier platform.

Squat increases with speed and in shallow water, reducing under-keel clearance and causing the vessel to trim by the stern.

MAYDAY (spoken three times) is the distress signal, used only when a vessel or person is in grave and imminent danger and immediate assistance is required.

PAN-PAN (three times) is the urgency signal for a serious situation that is not yet a distress situation; SECURITE (three times) precedes safety messages.

A MAYDAY call includes vessel name, position, nature of distress, assistance required, number of persons on board and any other useful information.

GMDSS DSC distress alert is sent on VHF channel 70; follow up with a voice MAYDAY on VHF channel 16.

Lifejackets must be fitted with a whistle and light; the lifebuoy with a light and smoke signal is used to mark a person in the water.

Man overboard: shout 'man overboard', throw a lifebuoy, press the MOB button on GPS, keep the person in sight and manoeuvre to return.

Fire triangle: heat, fuel and oxygen; extinguishing removes one leg, and the type of extinguisher must match the class of fire.

An EPIRB transmits on 406 MHz to the COSPAS-SARSAT system and should be registered with the national authority; a SART responds on radar (9 GHz).

Abandon ship is a last resort; take the grab bag, water, flares and radio, and stay with the vessel as long as it remains afloat.

In South Africa, the South African Maritime Safety Authority (SAMSA) administers the Merchant Shipping Act and issues skipper certificates of competency.

A Skipper Category B certificate permits coastal operation up to 40 nautical miles from the coastline, subject to the vessel's certificate of fitness.

The skipper is responsible for the safety of the vessel, crew and passengers, and for compliance with the vessel's certificate of fitness and manning requirements.

A vessel must carry the prescribed safety equipment for its category and area of operation, and equipment must be in date and in working order.

The International Regulations for Preventing Collisions at Sea (COLREGs) apply to all vessels on the high seas and in waters navigable by seagoing vessels.

The skipper must report accidents, pollution incidents and serious casualties to the relevant authority (SAMSA and port authority).

Local port regulations, harbour by-laws and speed limits apply within port limits and are enforced by the port authority.

A vessel must not discharge oil, garbage or sewage into the sea except as permitted by MARPOL; garbage disposal is recorded in the garbage record book.

The skipper must render assistance to persons in danger at sea, in so far as it can be done without serious danger to the vessel and persons on board.

VHF channel 16 is the international distress, safety and calling channel; channel 70 is reserved for DSC and must not be used for voice.

Channel 13 is the bridge-to-bridge navigation channel; channel 06 is used for ship-to-ship and channel 09 for port operations in many areas.

DSC (Digital Selective Calling) sends a digital distress alert with the vessel's MMSI number; the MMSI is a unique nine-digit identifier.

A VHF radio range is roughly line-of-sight, typically about 20-30 nm from a ship to a shore station depending on antenna height.

Radar: the range scale and gain should be adjusted so sea clutter is just visible; a radar fix needs at least two identified objects.

AIS (Automatic Identification System) transmits vessel identity, position, course, speed and heading, but AIS data must be verified against radar and visual observation.

GPS provides position, speed over ground and course over ground; it does not give speed through the water, which requires a log.

An echo sounder indicates depth below the transducer; the displayed depth must be corrected for transducer offset to give depth below the waterline.

Batteries and emergency power: VHF and navigation lights must have a backup supply capable of operating for the required period.