Weather

It is stressed that these weather notes apply only to the usual South Australian summer sailing season, especially from late December on. Outside this period, some of the anchorages described in these notes become highly dangerous, as they are open to heavy weather from the northwest to southwest.

The weather in summer on the West Coast usually consists of periods of warm to hot days, interrupted by the passages of cold fronts. The interval between fronts is often only three or four days. The intensity of each front usually is least in the northernmost parts and a change which produces a gale around Cape Catastrophe may bring only a fresh breeze to Ceduna. As the front passes, the wind generally soon turns from a weak north or north-easterly to a fresh to strong south or south-easterly. Really heavy weather is generally from the south-west. Northerly winds are frequently light and are not to be relied on for passage making. Occasionally a strong north to northwest wind will blow, accompanied by very high temperatures.

 On occasions, the area is affected by the after-effects of cyclones originating in Northwestern Western Australia. Usually, this only results in an influx of moist tropical air into the area and a disruption of the usual series of cold fronts. However, on March 24th, 1999, Cyclone Vance was sufficiently powerful to cross inland Western Australia from the Exmouth Gulf area and to reach the Great Australian Bight in the form of a strong depression. This brought northeast to northwest winds of near storm force to the West Coast, along with much flying dust. It is suggested that the mariner should be especially alert if a cyclone is off the Western Australian coast. Its progress should be followed and plans made to seek shelter in good time if it looks likely to repeat the performance of Cyclone Vance.

 Because of the repeated cold fronts and generally clear skies the temperature varies greatly. During the day near the coast it may exceed 40°C. and may fall below 10°C at night. Clothing suitable for this range must be carried.

 After a strong blow a large swell becomes established in the open sea and this may take a few days to abate. If the wind shifts much in the meantime cross-seas will be set up and this combination of swell and waves makes for awkward conditions.

When considering a voyage to these waters it must be remembered the the return journey will be mainly spent beating to windward. Sometimes it is possible to make fair progress by motoring or motor-sailing into light head winds in the morning, then taking advantage of a moderate to fresh afternoon sea breeze. The sea breeze tends to blow at right angles to the general run of the coast, though seldom actually reaching an exact right angle. If a sea breeze is expected while you are working your way south-east, stand well to the south side of the rhumb line in the morning and gain the maximum benefit from the sea breeze in the afternoon. Flat calms are quite common and so is the complete failure of the sea breeze. The passage south-east becomes quite a test of patience and weather understanding.

Weather forecasts from the ABC have been somewhat reduced recently and should not be regarded as adequate for safe sailing. A relatively inexpensive way of obtaining regular forecasts is to acquire a portable radio capable of receiving HF broadcasts on the marine frequencies. It is essential to get one able to receive Single Side Band transmissions.  Suitable radios are available from Dick Smith and similar sources.   Since 1 July 2002, The Bureau of Meteorology has assumed responsibility for HF weather forecasts and new stations have been established.  These are VMC Australia Weather West, at Wiluna WA, and VMC Australia Weather East, at Charleville QLD.   Twelve South Australian Coastal Waters forecasts are transmitted daily and Warnings are transmitted hourly.  For details of transmission times and frequencies, together with information on the most suitable frequencies to use, go to the Bureau's Guide to Marine Radio Services.

 In the absence of an HF radio, weather forecasts can be obtained from ABC Regional Radio. The station at Streaky Bay, which broadcasts on 693 MHz covers the entire West Coast. The broadcast times should be checked with the ABC before sailing, but generally there are two detailed forecasts per day during the week, with a rather reduced service during weekends. The Port Lincoln commercial station, 5CC, on 765MHz, also gives weather forecasts for the south central coast and gulf waters, generally on the hour or half hour. Strong wind and gale warnings are broadcast on the hour following their issue, usually accompanying a news bulletin. Although the West Coast is undoubtably a rough one, it should be remembered that safe anchorages are only about 50 miles apart. Should bad weather threaten, sufficient warning should be received to enable one to be reached, even if this necessitates abandoning a planned passage to make a strategic retreat. For this purpose a good engine and plenty of fuel will be valuable, as they enable good use to be made of the proverbial calm before the storm.
 
 

Tides.

Tides are generally of no great importance on this coast. On the open parts of the coast and at the islands the tide ranges through only about 1.5 metres. This makes choosing a spot to anchor easy.

 Tidal streams are important in those places where they run fairly fast and combine with the wind to create a hazard. In Coffin Bay and Waterwitch Channel the strong tides are no more than inconvenient, but at Venus Bay and Elliston hazardous breakers may be set up on the entrance bars in strong winds. To get to the West Coast, the tide races near Cape Catastrophe and in Thorny passage may have to be passed. These should be treated with great respect and if possible this area should be traversed when wind and tide are together. Take especial care to avoid the combination of a strong outgoing tide and a strong SW to SE wind. It was these factors which capsized Captain Flinders' cutter in 1802, giving Cape Catastrophe its name. As Flinders put it, "Nautici cavete!".

 The tide tables published annually by Flinders Ports contain all the tidal data available. For some ports it is a little meagre but this need not cause concern, because of the small tidal range.
 
 

Refraction Effects.

In summer it is common for abnormal refraction to play havoc with the range of navigational lights on this coast. At times. lights become visible at more than twice their theoretical range. This makes the Distance Off Tables published in the various books of nautical tables quite useless and the navigator should be careful not to be deceived.

 In daylight, it is common for the coastline to be much distorted by mirages. This may make it very difficult to identify landmarks.
 
 

Special Warning.

A number of areas on the coast under discussion suffer from a special navigational hazard in the form of cray pots and their associated buoys.
 
 
[ image: Irene A.]
Irene A working craypots about ten miles offshore, between Coffin Bay and Elliston.
When under sail many yachts are capable of sailing over these objects, especially if a folding propeller or a propeller working in a cutout is fitted. Under motor, however the chances of getting caught on a pick-up rope and its buoys are high. A good watch must be kept and in some areas motoring by night is not possible with complete safety. I especially noticed this problem between Venus Bay and Waldegrave Islands and between Point Sir Isaac and Point Whidbey. Some areas affected may be far out at sea, as the advent of GPS has made it possible to lay and retrieve pots from any position desired. Although not part of this coast, the vicinity of West Cape and Pondalowie Bay is especially bad and should be mentioned.

Various types of fishing vessels other than cray boats frequent this coast. Beware of boats towing different types of nets and the large fishing boats that tow tuna farms to and from Port Lincoln.
 
 
[ image: D Three.]
The now scrapped Japanese long liner, D Three, towing a tuna farm off West Point. She is making one to two knots and plunging a good deal in a small swell.
Some of this equipment extends several hundred metres behind the towing vessel and may not be obvious from a distance.

Because fishing vessels are liable to arrive in secluded anchorages at any time of the day or night it is necessary to show the correct navigation lights, including the anchor light. Places which seem remote to Adelaide based visitors are the usual work places for numerous fishing craft.

 It would seem wise to learn from the fishermen as much about their practices as possible.
 
 
 
 

 
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