In article .com,
"Stephen Page" wrote:
Thank you one and all for the guidance on tacking. What's the best to
read up some more? Also is tacking on a wind shift the thing I need to
get nailed down first and foremost? If so, how do you read a
wind-shift?
Best wishes
Steve
Steve, I like use a compass designed to assist with this.
From the TackTick website (a FAQ that addresses your question
(
http://www.tacktick.com/support/faq.asp?FID=32):
Your Tacktick compass has three primary functions:
To aid in the detection of wind shifts
To indicate the direction of the next mark
To help establish bias in the starting line
Establishing the mean wind direction
Launch in good time and allow at least half an hour to determine the
mean wind direction, as there may be an oscillating wind-stream with a
period of 30 minutes or more. Establish the wind direction by sailing
close hauled and noting compass headings, then split the difference
between the average port and starboard headings. Alternatively set your
Tacktick into its wind-shift mode and keeping an eye on the accuracy of
your set-up, adjusting as required until you are satisfied you have the
mean direction.
The more time you spend at this stage, the more accurately you will
establish the size and frequency of the windıs directional shifts.
Starting
The start line may not be set at exactly 90° to the mean wind direction.
The crew who position their boat at the favoured end of the line will
have an advantage. The digital precision of your Tacktick compass will
help you to establish which end is favoured. Consult your user guide to
understand how to work with your Tacktick at the start line.
Note that a last minute wind shift may appear to favour one end of the
line, but watch out! It may still be that the line is square to the mean
wind and it will then pay you to start at the apparently unfavoured end,
where the line will be less densely populated.
General hints on shifting winds
Discounting extreme meteorological conditions such as thunderstorms,
there are four main types of windshift:
1. A periodic shift in an oscillating wind-stream. In this case, success
depends on estimating the mean direction correctly, and it is usually
best to sail on the lifted tack. Note that it is possible to sail
through a small header and still be lifted in relation to the mean wind
- at this point you will pass a crew who simply tack on headers. Shifts
of this type are often experienced in a variable north-wester in UK and
continental waters. Small cumulus clouds are a trade mark of this type
of wind-stream.
2. A shift in the mean wind direction due to do changes in the overall
pressure system. The weather forecast and weather maps may warn of this;
which is why it is all important to be armed with an up-to-date local
forecast before going afloat.
3. A bentıwind due to shore effects.A Championship course is supposed
to be laid well away from land, but if the wind is blowing diagonally
offshore it nearly always pays to work a little way inshore early in the
beat as the opportunity allows. Should it then become apparent that the
inshore course is favoured, you are in a good position to take advantage
of it. Beware of going in too far too soon, or against an oscillating
shift.
4. Sea breeze.This may arrive as a reversal of the wind direction, or
the wind may swing towards the direction of the sea breeze. Try to
ascertain in advance what is the usual sea breeze direction. The basic
requirement for a sea breeze is sunshine: as the land is heated the air
above it rises, and the colder air is drawn in from the sea. A strong
offshore component in the prevailing wind - usually about 15 knots -
will nullify the sea breeze. There may be local signs to give a clue as
to the arrival of a sea breeze - ask around, but a good rough guide is
that for about 20 minutes before hand, the wind will slowly die. Once
the sea breeze is filling in, donıt look for oscillating shifts. As it
strengthens it will more closely approach is usual direction and later
in the afternoon, the process will tend to reverse. The sea breeze will
try to flow smoothly inshore and, being a rather shallow air movement
will tend to flow around obstructions such as cliffs, rather than over
them.
Using the shifts
The basic action required in an oscillating wind system is the opposite
to that when meeting major weather system shifts, bent winds or when the
sea breeze effect swings the wind-stream.
In the first case, it is necessary to tack on headers, in the other
cases it is usually best to sail on further when headed: the further you
sail the more the effect is likely to increase and the greater will be
the benefit when you finally tack for the weather mark.
And understanding them
If you are working an oscillating system and one of the other types of
shift appears - perhaps without warning - be prepared to cut your losses
and sail across to the better side of the beat. If for example, you tack
on a header and are then freed more and more, identifiably more than for
previous shifts, then you should suspect this is happening.
Serious winners are most likely to be those who appreciate the art of
this subject, and react rapidly to it.
The benefits of a Tacktick precision digital compass
Tacktick compasses are precise, lightweight, and easy to read, so you
can spend less time looking at the compass, and more time thinking
through the tactics. They are also portable and straightforward to
install, so you can take your Tacktick from boat to boat, and rapidly
set up for tactical racing.
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To respond, obviously drop the "nospan"?