Welsh 
Sailing Hazard
For
much of the year but especially in summer, the sails of dinghies
and yachts decorate Britain's coastline and many of its
inland waters.
Sailing is one of the most weather-dependent sports. Unfortunately,
wind is not just a useful source of power for sailing craft but
also a hazard. Strong winds can capsize boats, either directly
or in combination with the waves they may produce.
The wind is never steady. It always fluctuates between gusts of higher wind speed and lulls that may be so light as to be near-calm. However, sudden increases of wind on a larger scale can sometimes occur. These are called squalls and are often associated not only with strong, gusty wind but also with heavy rain.
The importance of any hazard varies with the skill level of the
crew, the type of boat and the kind of sailing being undertaken.
For example, a novice crew in a small boat may underestimate wind
strength before setting off. This is an easy mistake to make,
especially if they are launching from a relatively sheltered location.
Sailors who are more experienced are unlikely to be caught out
like this but are still vulnerable in other ways. Hard sailing,
especially in colder conditions, can tire a crew very quickly.
Exhaustion or exposure can creep up on them before they know what
is happening. For example, a dinghy crew might be having great
fun practising sailing across the wind, only to find when they
feel they have had enough that they do not have the reserves of
energy for a long struggle upwind or a tricky run downwind.
These days, yachtsmen do not have to rely on old folklore or gamble
on good weather. All sailors should pay attention to weather forecasts.
These are available through radio, television, the internet and
other means of broadcasting.
The particular forecast that is most appropriate depends on the
kind of sailing being planned. The shipping forecast broadcast
on the radio is perhaps the most useful to offshore sailors. The
terms used in it are precisely defined, and the information that
is included in it on pressure changes and movements of weather
systems is very useful to anyone with a deeper than average understanding
of meteorology.
When yachtsmen study meteorology as part of a training course,
either at sea or ashore, they are often asked to create a weather
map from a recorded shipping forecast as an exercise. The Royal
Yachting Association can provide forms called 'Metmaps'
that make recording and interpreting the shipping forecast a lot
easier. Completing one of these is a good exercise for anyone
who wants to go into meteorology seriously. The 'Metmap'
is a two-sided A4 form. On one side, a shipping bulletin broadcast
by the BBC can be taken down. On the other, a simple up-to-date
weather map can be drawn from the information contained in the
bulletin.
The shipping forecast gives a lot of information about visibility
at sea. This is because poor visibility can sometimes be a greater
hazard than strong winds. The forecast will not only give a guide
to overall visibility in terms of 'good', 'moderate'
or 'poor' but will often indicate if visibility is
poor for a specific reason, such as 'visibility poor in
showers'. This particular occurrence can give a sailor a
real fright, as views of nearby vessels or navigation marks can
be lost suddenly when showers occur.
Two possible hazards are not often mentioned in weather forecasts
for sailors but usually are in forecasts for land areas:
One of these is lightning, though the possibility of its occurrence
may be indicated indirectly in a forecast or station report as
'thundery showers'. In fact, lightning is not such
a risk to sailors as it might at first appear. Boats are surrounded
by a very good conductor of electricity – water –
and unless the boat suffers a direct hit, which is unlikely, the
current is dissipated much more quickly than on land.
The other neglected hazard is exposure to sunlight and
sunburn. Sailors are at particular risk for two reasons. First
of all, yachtsmen can get an increased dose of sunlight because
of reflections from the water. Secondly, they may not notice this
because the wind will make them feel cool and unaware they are
'cooking'. Many a sailor has returned to work on a
Monday morning with a 'yachtsman's tan' (from
the neck up!). This might seem a nice problem to have, but all
sailors should note the example of the America's Cup crews,
who often display extremely colourful suncream to protect against
harmful solar radiation.
Despite the apparently long list of hazards described, sailing
is, in fact, a very safe sport. It is also a sport where knowledge
of meteorology can increase a participant's enjoyment and
even give a competitive advantage!
At
Acapulco in 1968, sailors competing in the Olympic Games had an
unusual surprise from the weather. While not actually hazardous,
it was certainly not pleasant. One day, following a sudden squall,
the covers of the boats were covered with maggots, which had,
presumably, been drawn up into clouds by a whirlwind or waterspout,
only to fall out in a downpour of rain.
The
year 1979 is famous to yachtsmen for the worst possible reason.
In August of that year, during the Fastnet Race (from Cowes on
the Isle of Wight to the Fastnet Rock [51°24'N 9°35'W]
off south-west Ireland and back again to Plymouth), the fleet
of yachts ran into severe storms and rough seas. Fifteen lives
were lost. Despite 'survival conditions', many crews
kept records of the severe conditions, based on their barometers
and wind instruments. To the meteorologists who have analysed
the Fastnet Storm and its structure, these records have proved
invaluable. For a recent analysis of the storm, see the article
by D.E.Pedgley in the August 1997 issue of Weather (Volume
52, pp.230-242).
Shipping
forecasts are currently broadcast four times a day on BBC Radio
4 Long Wave. They are also available via the websites of the Met
Office and the BBC Weather Centre. In shipping forecasts, the
Beaufort Scale is used for describing wind strength. This scale
originated in the days of sail but is now defined precisely in
terms of the wind at a height of ten metres averaged over a ten-minute
period.