Friday, August 27, 2010

Danger zone

The area towards which we are sailing is deemed to be one of the two
potentially most dangerous sailing areas in the world with the Cape Horn
It earned its infamous reputation first because of the presence of the
so-called "rogue" or "freak" waves, more commonly called abnormal waves
which can be as high as 100 feet. Fortunately, so waves do not occur at
random in terms of time and location. For those waves to exist, the
university of South Africa has found that, whenever damage was caused to
shipping or yachting by those waves, three conditions had to be met.
First, the Agulhas current, which runs down the east coast on a SSW
direction, has to be at its maximum strength, which is around 5 to 6 knots.
Second, there has to be a "buster" or coastal low, racing up the same
east coast and generating SW winds of up to 70 knots.
And last, you would have to be in an area which is east of the 200
meters depth line, 20 miles out, between the latitude of Durban (in fact
a little further north than Durban) and Port Elizabeth.
If you are in there and a buster is showing up, if you are in a small
boat, race inshore with a smaller depth, and if you are on a big one,
get the hell out of it and go off shore.
If you don't believe that it can destroy a tanker, google "World Glory
disaster", which occurred on May 31st, 1968, when a 50,000 tons tanker
belonging to Niarchos shipping, sailed over a freak wave, broke in two
and sunk.

Sailboats planning to sail around south Africa out of the Indian ocean
should first aim for a position around 150 miles south of the southern
tip of Madagascar and then aim for a position halfway between Richards
Bay and Durban. Statistically speaking, the storms and the abnormal
waves don't go that far north. Once you are off Durban, if you have a
nice 2 to 3 days weather window, then aim for East London. Otherwise,
hunker down in Durban. After East London, you need a 36 hours window to
get to Port Elizabeth, then another 36 hours to go to Mosselbay, then
one day to an anchorage in the lee of Cape Agulhas, and then. once you
get a nice SE wind, you are only 125 miles from Capetown.

Needless to day that to undertake this kind of voyage, you need to be
well covered weather wise and have a boat carefully prepared for an
eventual storm.
On Papy Jovial, I regularly check via email (using my iridium sat phone
as a dial up modem) the grib files (a weather map that you can overlay
on your chart plotter providing up to 7 days forecast) from 3 different
systems, MaxSea, which is my navigation software, UGrib, a free system
from Grib US and Expedition LT from New Zealand.
I also have outside help.
First, Tom, previous owner of the boat for 22 years, whose son used to
to weather in the Navy, and who has been with me everyday, sometimes
twice a day, by email, to provide me with weather outlook and forecast.
Second, Bruce, professional weather router, who works with the national
sailing team of Australia, with ARC, and has been in this business for
more than 30 years.
And then, the South Africa Mobile maritime network on SSB, run by
Alistair and Graham. I first made contact when I was still 3,300 miles
away, and since, when at sea, I talk to them and get the weather ahead
of me.

I am still a little nervous, since you can never be 100 % guaranteed no
problem. In fact, most people say that this passage should only be done
around November. Yet, the worst storm in decades that damaged most of
the marinas of the south coast of South Africa occurred in November. I
am confident that I will get to Capetown safely and comfortably.

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