Passage planning
Sources: Yachting World, OSASA, Noonsite (secondary); Mallory. Builds on: L3.1. See also: Coastal Skipper/Yachtmaster Offshore Theory.
The shape of the voyage
A yacht coming from the Indian Ocean typically makes landfall at Richards Bay or Durban, then works south-west along the coast to Cape Town, and later leaves for St Helena, Brazil or the Caribbean. The coastal part is short in miles but is where most of the risk lies.
Arriving from the Indian Ocean
Yachting World describes the classic timing: yachts leave Réunion in November, balancing the start of the tropical cyclone season (peaking from December) against the Southern Ocean cold fronts that reach further north earlier in the year. The passage of about 1,400 miles to Durban or Richards Bay needs roughly ten days of suitable weather, which long-range forecasts cannot promise. Arriving with a north-easterly running with the current is ideal; if a front approaches, heaving to offshore is safer than trying to cross the current in wind against current.
Working the coast
The coastal pattern repeats every few days:
- A north-easterly blows ahead of an approaching front. Wind and current run together: good sailing towards the Cape.
- The front arrives and the wind backs, often quickly, to a south-westerly. Wind against current: dangerous seas near the shelf edge (L3.1).
- The south-westerly eases and the cycle starts again.
The technique is to leave port at the start of the north-easterly, run for the next suitable harbour, and be in before the south-westerly. If you cannot reach port, get inshore to about 100 m depth or well offshore, as Mallory advises.
A worked example: the current and your ETA
A 40 m yacht making 12 knots through the water plans a 250-mile leg (illustrative distance).
| Current | Speed over ground | Time |
|---|---|---|
| 3 kn with you | 12 + 3 = 15 kn | 250 / 15 = 16.7 h |
| 3 kn against you | 12 - 3 = 9 kn | 250 / 9 = 27.8 h |
The adverse set costs about 11 hours. If the front is forecast in 20 hours, the difference decides whether you are in port or at sea when it arrives. Plan for the current's actual position and strength, not the best case.
WARNING - Commit early, abort early The decision to sail should include the decision where to go if the forecast changes. Write down the refuges and the time to each before leaving.
Passage plans and help
- Passage plans. OSASA advises filing a departure plan (for example through passageplan.co.za), which notifies the next port and helps with berths. Individual ports have their own flight-plan forms (L1.2).
- NSRI. The National Sea Rescue Institute runs a 24-hour emergency operations centre. OSASA gives +27 87 094 9774 and VHF Ch 16.
- Refuges. OSASA lists anchorages such as Jeffreys Bay, St Francis Bay, Plettenberg Bay and Struis Baai, useful in the right wind but not all-weather.
The Cape itself
Rounding Cape Agulhas and the Cape of Good Hope into False Bay or up to Cape Town brings the same logic: wait for the window, go, and be in before the next front. In summer the south-easterly blows strongly on the Cape Peninsula; OSASA notes that some smaller ports are unusable in a south-easter.
TIP - Berths in November and December The same season brings the cruising fleet to South Africa. Noonsite and OSASA both warn that berths fill quickly; book ahead and have a fallback.
CAUTION - No schedule survives the Cape Tell owners, guests and yards the weather sets the dates.