Richards Bay to Cape Town

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WorldSouth AfricaRichards Bay to Cape Town
Richards Bay to Cape Town
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The "Cape of Good Hope" route

Description

The passage to Cape Town is best undertaken between January and March and with prudent monitoring of the weather reports should be interesting and quick, on the back of the Agulhas Current.

Monitor the weather reports and when a 2 to 3 day spell of favourable wind is forecast (usually just after a southwester) set sail immediately as the first possibility of shelter is East London, 250M away. Head straight out to a couple of miles beyond the 200m contour line to pick up the strong, south-flowing Agulhas Current. Avoid sailing too far out in case it becomes necessary to come back in towards the coast - out of the current's flow in case of the onset of a southwesterly.

Keep an ear on the weather reports and an eye on the barometer so as to plan for finding a "bolt-hole" if necessary. The South African weather service will give a 2 to 3 day warning of approaching fronts (southwesterlies) - (see the radio section on the South Africa page for transmission details).

The current gets stronger between East London and Port Elizabeth and sometimes has a strong onshore set. After Port Elizabeth there are many places to take refuge in the event of a southwesterly blow.

It is not wise to sail round Cape Agulhas if the weather is not favourable. The favourable southeasterly does prevail at this time of the year however.

Many cruisers manage this passage in one leg at this time of year and report a "fantastic", fast passage.

Passage planning

The sailing route from Richards Bay/Durban to Cape Town is governed by three major factors:

  • The Agulhas Current: This current is one of the great ocean currents of the world, running mainly from northeast to southwest, following the two hundred meter contour of the continental shelf and dissipating over the Agulhas Bank south of Mossel Bay. The main axis of the current is on or near the two hundred meter line and can run at up to 6 knots at it's fastest point.
  • The Variable Weather Patterns: These patterns are governed by low and high pressure systems moving across from the Atlantic Coast of South America and travelling eastwards up the eastern seaboard of the South African coast.
  • Sheltered Harbours and Anchorages: The third factor is the lack of sheltered harbours and anchorages, particularly between Durban and Port Elizabeth. From S.African Cruising Notes by Tony Herrick.

Charts

Source
Chart Number - Chart Name
Chart Number - Chart Name
Source
Chart Number - Chart Name

Weather

The major wind belts around Southern Africa are influenced primarily by two high pressure systems, namely the South Atlantic High (SAH) and the Indian Ocean High (IOH). These high pressure systems form part of what is known as the 'subtropical ridge'. Because of the effect of Coriolis force, the winds associated with such high pressure systems are deflected to the left in the southern hemisphere, and therefore blow around the highs in an anticlockwise direction. Such systems are also called 'anticyclones'. In contrast to the high pressure systems, to the south there is a belt of low pressure systems, or 'cyclones', with associated winds blowing around the lows in a clockwise direction.

The closer the isobars are to one another around such highs or lows, the greater the pressure gradient, and consequently the stronger the associated winds. Latitude also affects wind strength, with the winds being weaker closer to the poles for a given pressure gradient. However, because of the balance of forces in the two systems, anticyclones tend to be large, with the strongest winds near the perimeter and light variable winds near the centre. In contrast, for cyclones the strongest winds are associated with small, deep systems.

Frictional effects at ground or sea level cause an imbalance between the pressure gradient and Coriolis force, with the result that the winds do not blow exactly parallel to the isobars. There is a net flow towards the low pressures, causing convergence in cyclones (lows) and divergence in anticyclones (highs). The result of this is an updraft in the centre of a low together with the possibility of cloud formation and rain, while the centre of a high will be cloud-free, drier and hotter.

The air above particular regions may acquire reasonable uniform properties while passing over these regions. Temperature is one such property that can be used to identify air masses. But what is of importance are the rapid changes that can occur when one air mass is replaced by another at a particular place.

Weather, in terms of clouds, rainfall, winds, etc., results from the vertical upliftment of air. In particular, fronts occur when two air masses with substantially different temperatures meet. The denser air undercuts and forces the less dense air upwards. Cold fronts occur when, over a period of time, cold air replaces warm air at a particular place. Warm fronts occur when warm air replaces cold. Quite apart from temperature changes, abrupt changes in wind can also be expected with the passage of a front. There are also distinct cloud formations associated with such fronts. Thus cirrus, altocumulus and stratocumulus clouds typically precede a cold front, with the possibility of cumulonimbus clouds bringing heavy rain. On the other hand, the clouds associated with warm fronts are cirrostratus, altostratus and nimbostratus.

On the South African east coast, the duration of an individual frontal low is usually from three to five days. Cold fronts tend to travel faster than the associated warm fronts, and an occlusion occurs when they merge. In these conditions the warmer air rises above the surface, and the system decays rapidly. From S.African Cruising Notes by Tony Herrick.

Weather Windows

Give the best time/s of year for this passage and expected weather conditions.

Navigation

ABNORMAL WAVES: It is a known fact that giant waves occur on the South African coast in the Agulhas current region, where southwesterly gales prevail against the southward flowing Agulhas current. Professor Mallory of Cape Town University analysed the recorded conditions that prevailed each time a number of ships were damaged by exceptional waves, and found that in all cases the dominant waves were always from the southwest.

The weather patterns play a major part in that the most dangerous period occurs when cells of low pressure are moving along the coast in a northeasterly direction. These lows are a regular feature of the eastern seaboard and it often happens that during their passage the wind can change from a near northeasterly gale to a southwesterly gale, sometimes in a matter of minutes. The southwest wind then reinforces the existing waves generated by a short choppy sea, which acts directly against the Agulhas current.

It is the interaction between the strong southwesterly wind and the strong south flowing current which at times can reach 6 knots that creates monstrous freak waves, of which the charts warn: Abnormal waves of up to 20 meters in height, preceded by deep troughs may be encountered in the area between the edge of the continental shelf and twenty miles to seaward thereof. The warning also describes the necessary evasive action to be taken under unfavourable conditions, namely, to stay clear of the areas seaward of the continental shelf. In other words, move inshore, inside the 200 meter line. This well established rule has given rise to the belief that the bottom topography plays a part in the generation of giant waves, but in fact this only plays an indirect role.

Please remember that the conditions along the southeast coast of South Africa are unique; the region can only be made safer through an understanding of the forces involved and by treating the seas with the respect they deserve, regardless of loss of time. Do not have a deadline to meet at the other end. MANY South African sailors sail along this coastline all the time - simply prepare yourself with all the knowledge and information that is available for a safe passage. (Reference is made to a research paper - "Giant Wave - Anomalous Seas of the Agulhas Current" - by Ecxart H Schuman.). From S.African Cruising Notes by Tony Herrick.

Communication

Also see World Cruiser's Nets

Possible Departure Points

Route/Suggested Stopovers

  1. Starting from Richards Bay/wiki/Richards_Bay_to_Cape_Town#.5B.5BRichards_Bay.5D.5DHarbour icon Richards Bay [[Richards Bay to Cape Town#Richards Bay|Richards Bay]] 28°48.600'S, 032°05.670'E
  2. xx nM Durban/wiki/Richards_Bay_to_Cape_Town#.5B.5BDurban.5D.5DHarbour icon Durban [[Richards Bay to Cape Town#Durban|Durban]] 29°52.511'S, 031°00.514'E
  3. 255 nM to East London/wiki/Richards_Bay_to_Cape_Town#.5B.5BEast_London.5D.5DHarbour icon East London [[Richards Bay to Cape Town#East London|East London]] 33°01.578'S, 027°55.346'E
  4. 134 nM to Port Elizabeth/wiki/Richards_Bay_to_Cape_Town#.5B.5BPort_Elizabeth.5D.5DHarbour icon Port Elizabeth [[Richards Bay to Cape Town#Port Elizabeth|Port Elizabeth]] 33°57.19′S, 25°38.62′E
  5. xxx nM to Knysna/wiki/Richards_Bay_to_Cape_Town#.5B.5BKnysna.5D.5DHarbour icon Knysna [[Richards Bay to Cape Town#Knysna|Knysna]] 34°05.09′S, 23°03.58′E
  6. xxx nM to Mossel Bay/wiki/Richards_Bay_to_Cape_Town#.5B.5BMossel_Bay.5D.5DHarbour icon Mossel Bay [[Richards Bay to Cape Town#Mossel Bay|Mossel Bay]] 34°10.453'S, 022°08.726'E
  7. xxx nM to SimonsTown/wiki/Richards_Bay_to_Cape_Town#.5B.5BSimonsTown.5D.5DHarbour icon SimonsTown [[Richards Bay to Cape Town#SimonsTown|SimonsTown]] 34°12.504'S, 018°38.463'E
  8. xxx nM to Hout Bay/wiki/Richards_Bay_to_Cape_Town#.5B.5BHout_Bay.5D.5DHarbour icon Hout Bay [[Richards Bay to Cape Town#Hout Bay|Hout Bay]] 34°03.1′S, 18°20.91′E
  9. Finally after xx nM you arrive at Cape Town/wiki/Richards_Bay_to_Cape_Town#.5B.5BCape_Town.5D.5DHarbour icon Cape Town [[Richards Bay to Cape Town#Cape Town|Cape Town]] 33°52.635'S, 018°27.257'E

Possible Arrival Points

Distance & Duration

Add table.

Forums

List links to discussion threads on partnering forums. (see link for requirements)

Links

References


Comments

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